- July 5, 2016 at 7:28 pm #28772
Hello my friends. I would like to write, and give my opinion of what I have seen, read, witnessed, learned, and demonstrated while pursuing the goal of shooting cast bullets at high velocity, as well as share a few points of my progression of personal discovery in this discipline.
Many of you have participated and followed along with me since my arrival here in 2011, as well as the pursuit of others who were here before, and those who have joined in along the way.
This article would not be complete without an explanation of where I started and how I got here.
I was always a gun nut and I was always a hopeless do-it-your-selfer. I have been casting since I was an adolescent. My father may have been a little too consenting by teaching me how to cast and shoot when I was so young, as well as giving me free access to power tools, reloading components, and firearms, but he believed in freedom, and he wanted me to know what freedom really feels like, and he was successful in that undertaking.
I made my first pistol when I was 14 years old (I still have it) and it used black powder to shoot 35 caliber rifle bullets (358318). Over the next few years, I experimented with quite a few of my father’s molds, shooting quite a bit of 30-30, 35 Remington, 45ACP, and 357Magnum. In truth, I doubt I have ever bought and used a single box of store bought ammo for those calibers (except 30-30 once when I needed brass).
After shooting thousands of rounds of these, I discovered high power bolt action rifles, and the accuracy and precision that could be had from my hand loads using jacketed bullets. Very quickly, I decided that cast bullets were best suited to pistol ammunition, while jacketed bullets in the green box, were very worth the cost for the speed and accuracy obtained from them.
Speed became the thing I enjoyed most. Getting the bullet to the target as fast as possible (within the bounds of safety) was what I liked, but I would never go below 30 caliber. My trusty 30-06 was great fun to shoot, and 1/2MOA was normal, but the speed just wasn’t there, and the recoil was no issue for me at all, so I considered buying something with a little more to offer, and began casting my wandering eye towards the 30 caliber belted magnums. After careful consideration, I landed on 300 Winchester Magnum as the very best next step up, and I bought a Remington 700 BDL in this caliber.
Over the next couple years, two things happened that changed the course of my pursuits: 1. I burned out the barrel on that rifle, and 2. I became a father.
Any of you who ever started a young family know what having a child does to your ammunition fund, and my case was no different. When I finally got back to my shooting, I found that my available income was greatly reduced from where it was before, and I started applying myself to find a way to shoot cast bullets in rifles more effectively, especially at HV.
I explained my plan to my father, and he mentioned that cast bullets had been shot at 3000fps in a 300WinMag using paper patched bullets. I started researching this paper patched bullet discipline, and it took no more than a few internet searches to find that the very best place on the internet to learn how to make paper patched smokeless cartridges was none other than our fair site castboolits.gunloads.com.
I joined the forum and started applying myself to learn how to do this. About the time I learned how to get paper patch working in my rifles, I realized that there was a vast amount of knowledge relating to shooting standard cast bullets that I had never learned, so I took a step back, pulled out the old molds, and started seeing how fast I could push them. I began building custom rifles almost immediately for the purpose as well as reloading equipment because this allowed me to experiment with quality that was a “known entity”, and gave me flexibility to change things as needed to achieve success.
I saw that there were several members on the forum who claimed to be able to shoot HV with cast bullets, and I did my best to understand all there is to know about shooting HV cast bullets.
You name it, if it had to do with shooting cast at high velocity, I made it, modified it, improved it, or used it. No holds barred, and I honestly tried to understand all the methods that claimed to deliver true HV accuracy.
I have observed several interesting things in this pursuit, and come to identify several methods which allow the possibility of shooting cast bullets to high velocities (2500FPS-3000FPS)
One method called “The low RPM method” utilizes custom slow twist barrels to achieve HV with accuracy.
Another method, I call “The high RPM method” which refers to shooting HV with standard 10-12 twist barrels.
There are two other views which are: paper patching, and “enhanced alloys”.
Of course there is a fifth view, that being the copper jacketed bullet (however, this will be mentioned only in passing).
The purpose of this thread is to describe my personal observations that may be of great value to those who are looking to understand the phenomena posted on castboolits.com and why it is difficult at times to reproduce in their own rifles. Please just try to take it with a grain of salt, and think about what I’m saying as I really don’t think any of the methods are doing anything that the others are not doing and I believe I understand how and why each of them work. Read on, and form your own conclusion. After all, it’s just “the opinion of that crazy goodsteel guy on cast bullets.” LOL!
Most of you have probably experienced the “RPM threshold” phenomenon where your cast bullet groups suddenly become minute of berm? I recently experienced this with one of my cast bullet rifles in 35XCB caliber. As long as I stayed below 2590FPS, my bullets would go into less than 2″ at 100 yards, but when my loads crossed 2600, the group opened up to 10″ or more. Just 10FPS between reasonable accuracy, and horrible accuracy. That’s the RPM threshold.
I started my pursuit of HV cast bullets from the “High RPM” point of view, and some have demonstrated pretty impressive shooting at 100 yards. The theory goes that if you match your alloy to your powder selection and barrel harmonics, you can push a relatively soft bullet at high velocity and maintain usable accuracy at long range. This method is anything but plug and play, and the best advice I have gotten is to just start shooting and figure out what your gun wants, and don’t be surprised if it takes 2000 rounds to get it right. I’m pretty much convinced at this point that advice is about as good as it gets, because it is a very specific condition for each particular rifle.
That said, I have no doubt that this is possible and has been done by numerous shooters for many years, and I think I know why it is possible as I will describe.
Another view that I have personally had excellent results with is the “Slow twist method” which simply negates the RPM threshold by using a new barrel in slower twist to make it so that the bullets never cross 140,000RPM so they do not ever get to the point where the groups open up dramatically. This method uses hard bullets made of classic alloys like Linotype, and Lyman #2 or COWW+2% tin water dropped. Speeds in excess of 3000FPS are easily achievable with barrels of 16 and 17 twist, and accuracy of 1.5MOA is possible and very common at ranges of 300 yards and probably further.
Another method that I have only dabbled in a little is the copper enhanced alloy method.
This method uses common alloys that have been spiked with copper to make them harder and tougher than anything that could be obtained with standard alloys. These bullets can be pushed to reasonably high velocity in excess of 2500FPS, although accuracy figures have escaped me. I get the feeling that it is similar to the other methods mentioned and probably well under 2MOA at 2500FPS. These bullets are too hard/tough to hunt with unless special precautions are taken such as hollow pointing them (my opinion only).
The final method I have looked into is paper patching. This is a very difficult pursuit of the perfect paper, the perfect wrap, the perfect alloy, and the perfect size of both the core, and the paper. However, it is demonstrated that it is very possible to achieve 1″ groups at 3000fps with this method if you get it all right. Not too shabby if you can do it!
So that’s a brief overview of the four principle methods of HV cast bullets.
It is my opinion that all these methods function on the same principle, and have their own way of dealing with the thing that destroys cast bullet accuracy, and makes the RPM threshold a reality for so many people.
One of my favorite quotes from Albert Einstien says: “Once we accept our limitations, we can move past them” but it is my opinion that you have to know what your limitations are in the first place before you can either accept them, or move past them, and in the case of cast bullets, those limitations are very hard to see.
However, I believe I may have discovered what the limitations are, or something very close to it.
It happened back when I was planning to design the 30XCB bullet. I was attempting to do anything I could to see what actually happens when the bullet is engraved. Many have postulated that “the bullet gets damaged as it enters the rifling” but I could not understand why or how that is possible given that my rifles are very carfully designed and built to be perfectly concentric with chambers and throats that are perfectly aligned in every way, and my ammunition is built to the same exacting standards! I’m willing to admit that my bullets get damaged, but I take issue with the assertion that they are damaged in an way that is not perfectly concentric, and for the “damaged bullet” assertion to be true, they would have to be damaged on only one side, or in a misaligned fashion. That idea may hold up on your Wal-Mart Remington, but not on an MBT custom rifle! It’s impossible. Especially when you figure the fact that both the Wal-Mart Remington and the MBT flame out at exactly the same RPM? It just doesn’t hold water.
Add to that, the fact that I have recovered many bullets from the berm that were shot over the RPMTH and I saw no damage whatsoever (reading through the berm damage obviously). Not a single clue. Not a single hint of bullet imbalance based on visual inspection.
Of course, all of the bullets I observed were almost completely destroyed by the impact, so I needed a way to engrave the bullet like it would be as it was fired from the rifle with a full charge of powder.
After looking at a few pressure trace graphs, I thought that maybe I could use a small charge of fast burning powder to stuff the bullet into the rifling in a very similar fashion as it would be when a column of slow powder was ignited behind it, but without the subsequent buildup of pressure that accelerates it into warp speed and destroys it on the backstop. All I realty need is the first inch of bullet travel!
So I loaded one of my rifles with a very small charge of Bullseye powder and used it to shoot bullets into a bucket filled with wet sand.
I dug out the bullets as they were shot and scrubbed them gently with Dawn dish soap and a soft bristle brush in the sink, patted them dry, then observed them under magnification with a Bosch and Lomb microscope.
At first, I didn’t see anything that looked out of place. I saw a small amount of skid as the bullet engraved the rifling, but it was very concentric and even. Nothing was really standing out at me that would suggest an imbalanced bullet. I shot every 30 caliber mold design in the shop and carefully observed each of them.
The big light bulb moment came when I was observing a Lovern style bullet (311466) and I noticed that the rifling marks were not straight. It seemed that the bullet had become twisted when it gently impacted the wet sand in the bucket. I did the test again, and fired a few of that same bullet and looked at each one under magnification. They all exhibited the same slightly twisted look.
Suddenly, I realized what I was looking at! The bullet is a soft but strong material! What was happening was that the nose of the bullet engraved first and was commanded to spin by the rifling (as evidenced by the slight skid marks on the nose) while the base was still stationary. The base of the bullet caught up a little slower than the nose of the bullet, but when the bullet exited the muzzle, the bullet was strong enough to try to right itself in flight. Effectively doing a “dishrag twist” as it flies. There’s no way that centrifugal force is going ignore that vibration. At a certain point (I believe a VERY SPECIFIC POINT) the centrifugal force produced by the RPM is going to use that to overcome the stabilizing fact of the bullet’s spinning, and thus you have the RPMTH. I think I just popped the big red balloon the RPMTH was hiding behind.
Now, armed with this knowledge, I designed the 30XCB bullet. My objective was to make the rifling engrave the bullet right in the middle of the projectile, so that neither the nose nor the base had much chance to get engraved in a strange way (in fact, the nose has no opportunity at all, and nose slump is the only thing to worry about). The bullet was designed to be controlled by the rifling at all costs, to obtain as much BC as possible. It was designed to be balanced and to resist getting twisted head-on by being cast of strong alloys and being designed to survive every stage of the firing process. I believe the instant success of this bullet in all kinds of rifles across the board speaks to the fact that I was definitely onto something, and this bullet ended up being the golden ticket for the HV slow twist method.
Now, let’s apply this knowledge to the other methods of shooting HV cast bullets and see how it plays out.
HV with standard twist:
The hallmark 30 caliber bullet of the HV with standard twist crowd is the venerable Mi-Heck 30SIL. This bullet is everything the 30XCB is not. It has a progressive nose that is hourglass shaped and touches the crest of the ogive and the flare of the skirt just in front of a positively cavernous lube groove which renders a suspiciously thin core that connects the front of the bullet to the little base that holds the gas check. Given what I learned from the sandbox test (which this bullet was part of) this has to be the worst possible design in the history of HV shooting. Or is it? The fact is, wherever I would opt to make the bullet strong, the designer of the 30SIL designed in a weakness. Add to this the fact that the people who use this bullet to achieve unbelievably high velocities also insist on alloys that are very similar to those used in jacketed bullets (some even use range scrap exclusively) which have (amongst other properties) the ability to be twisted without springing back. In other words, the bullet engraves the rifling in the same twisted fashion and takes a set in that condition while still in the barrel which allows it to emerge as a stable projectile capable of much greater RPM, and theoretically, the harder you push it, the better it will like it, to a certain point.
Very few have been able to feel out the specifics of this method with even one rifle but it has been done numerous times.
Let’s consider paper patched bullets:
It is my belief that the paper jacket works just like a copper jacket. It protects the core of the bullet (our cast bullet in this case) from getting twisted by the rotational inertial as the bullet is being spun up and engraved. The patch itself allows the bullet to slip beneath it. This is one big reason you NEVER get good results if you glue the patch to the bullet. I’ve got news for you, once the bullet leaves the barrel, it doesn’t matter whether the patch stays attached, or comes of as confetti or paper dust. The main function of the paper patch is to help the bullet survive the first inch of acceleration, and get it out of the barrel in an “at rest” fashion, which it does quite well. The main problem with paper patching is getting a paper that protects the bullet well while keeping it perfectly aligned in the barrel, while not jacking with the flight as it is jettisoned at the muzzle. Basically, the paper does a great job of protecting the bullet, but it does an even better job of jacking up umpteen other things if you don’t do them right! Gotta TAME that rascal!
Copper enhanced alloys:
This is simply strengthening the bullet so much that it can resist getting twisted. That’s all I’m going to say about this method because I have not personally experimented with it enough but it can’t be left out of the discussion.
Now, I’ll tell you something else concerning jacketed bullets:
THEY DEAL WITH THE SAME ISSUE and they deal with it better than anything else.
I have cut open quite a few jacketed target bullets and XRF tested them to see what alloy is used in their cores. By and large, the alloy is pure, dead soft lead. That soft lead core, combined with a hard jacket made of perfect bearing material does something that our bullets cannot ever do. The cores twist and settle perfectly in that first inch of rifling and actually work like a shock absorber or a mercury recoil tube. That bullet leaves the muzzle as dead as a hammer with a hard jacket that will keep it together during enormous RPM and centrifugal force, and keep it safe all the way to the target up to 2 miles away. You can’t beat that with a wet squirrel.
This is what I have gleaned from the XCB project, and where my mind has been while I have been working towards HV cast bullets. I’m hoping people do not get the impression that there is a single way to do this, or that one way is smart, while others are dumb etc etc etc. Shooting HV cast bullets is a hard thing to do, and there are several ways to do it. One thing I think I can say with certainty is that it’s expensive. You have to pay the piper with time or money and there is no way around it.
So HV cast bullets is not economical which is the reason many people get into this sport. It’s still cool as all get out, and gets you lots of looks at the range from people who can’t shoot an AR-15 as well as you do your 30-06. LOL!
For me, it was about seeing what’s out there, how it works, and why it works. I’m satisfied with what I have learned so far, and what has been achieved. I hope everyone here has benefited greatly from the efforts of everyone who contributed to the HV cast bullet pursuits described (and at times fought over) by all involved. I can say it’s been the most exciting and grandest project I’ve ever attempted, and I appreciate having a place to tell people about it instead of the knowledge being mine alone and lost to anyone who might wish to do the same thing.
- July 5, 2016 at 7:54 pm #28773
As an addition to this post, I would like to say that when shooting cast bullets at HV, it’s not enough that the bullet merely exit the barrel at high speed. You have to grasp enough accuracy and precision to make HV cast actually GOOD FOR SOMETHING otherwise it’s just playing with a chronograph.
When a claim is made that cast bullets can be shot at high velocity, that claim MUST be accompanied by a standard of distance and accuracy for it to mean anything at all.
I say this, because there are many who manage to get 5-10 shots to land in a decent group at 100 yards (or even 50) and snap their suspenders claiming they have succeeded where so many others were frustrated. These people become very irate when you ask them to demonstrate accuracy at longer distances. When they refuse, and you then ask why they need to vaporize deer at 50 yards when the same bullet traveling at 1500FPS would do as well or better without all the meat damage? They become even more irate. They simply could not be bothered with logic under any circumstances.
For me, the whole reason for shooting HV cast in the first place is because shooting a deer at 300 yards with a 165 grain cast bullet that left the barrel doing 1900FPS is just bad sportsmanship to say nothing of being flat out unethical. The whole point is to extend the effective range. Since the whole point is to extend the effective range, it stands to reason that I would shoot at extended ranges regularly in order to see whether I had succeeded or not.
The reason many who claim blistering speeds, way over the RPMTH, get so darn irate about it is because they know they couldn’t hit the broad side of a barn at 300 yards regardless of their small groups at 100. One fellow (we’ll just call him grey mouse) who I was actually very good friends with before the XCB project got under way, told me that he attempted to shoot his HV loads at extended ranges and was shocked at the wretched accuracy he demonstrated, but he was still convinced his issues were just barrel harmonics, along with the idea that our own Larry Gibson was completely wrong about RPM and it’s effects on cast bullets. Of course, this was never brought up in any of his mile long excerpts on what was, according to him, required to shoot at HV and break the RPMTH.
The truth is, the further you get away from the barrel, the more difficult it becomes to control cast bullets by any means other than a copper jacket or a slow twist barrel.
This is why my signature includes a quote by Albert Einstein “Once we accept our limits, we go beyond them”. This concept is very apparent when you try to develop a solid solution to shooting cast bullets at extended ranges, while retaining enough usable energy to hunt medium sized game with. You owe it to yourself and to your quarry to do what it takes to obtain true, repeatable, solid accuracy, precision, and energy at long range.
Now, like I said, the jury is still out on whether there’s any way on earth you can shoot cast lead bullets of any composition from a fast twist barrel at 300 yards with enough juice and malleability to get the job done on a whitetail deer. I believe anything is possible, but given the absolute refusal of the proponents to provide any shred of evidence in support of their ability to stick all ten shots in a paper plate at that range repeatably, I doubt it.
However, if you screw a 14-16 twist barrel and use savvy powder selection and superb casting/loading techniques, this goal becomes not only possible but commonplace.
- July 5, 2016 at 10:25 pm #28776ken campbell iowaParticipant
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great stuff …
your ” springy bullet ” theory/observations seem unlikely …. but then all the ” likely ” theories have not resulted in easy success with cast at 2700 fps either … ha …
thanks for the essay; lots of fresh ideas to consider .
- July 5, 2016 at 11:25 pm #28778
Well, like you say it’s just s theory, but it does seem to fit with all the evidence.
1. Larger calibers have a lower RPMTH than smaller calibers.
2. Shorter bullets have a higher RPMTH than longer bullets.
3. The “damage” to the bullet that theoretically causes the RPMTH is completely unseen and unsubstantiated. It is the only assumption made, and does not explain why the same bullet design cast of harder allot has a higher RPMTH.
4. Harder, stiffer bullets have a higher RPMTH.
5. Paper patching will successfully Segway a previously unsuitable cast bullet way past the supposed RPMTH even though the inherent imbalances of the cast bullet are still present and rifling marks are transferred through the paper to the bullet very clearly.
6. A bullet with a very long bearing surface, recovered in tact, exhibit rifling cuts that are not a match the the barrel that produced them.
7. Slower powders that engrave the bullet more gently have ever been known as the go-to propellants.
8. Those who have shot HV (albeit at short range) have done so with designs that have weaknesses built in that would allow the base of the bullet to more easily take a set in its theoretical “twisted” fashion and more importantly, make it difficult for it to snap back in line after its exit from the barrel. Added to this, I would submit the insistence of that crowd to using soft alloys with no tin and low antimony content. All of this points to a bullet that will go through a sizer and emerge as an exact duplicate of its size, and also that the bullet will emerge from a barrel in the same way. Interesting.
9. The success yet another crowd has had (men such as 357maximum) where they insist on infusing enough copper into their alloys that the resulting bullets can withstand the twisting force of the engraving event (my words, not theirs).
10. And finally, it’s not much of a point, but you made it yourself: The XCB rifles, cartridges and bullets were specifically designed by me to resist this exact theoretical phenomenon and have been proven to regularly and consistently offer a plug and play solution to HV shooting with standard cast bullets.
That’s it in a simple ten point nutshell.
Like i said, if I’m wrong, I want somebody to show me different, but so far, any opposing theory has ignored some or all of the evidence given above, and that is unacceptable, and bad science at its core. When somebody can show me how a bullet gets “damaged” in a way that answers ALL the above evidence satisfactorily, I’ll retract my theory and adopt the alternative right away.
Till then, I will continue with the assertion that my rifles are practically perfect in their construction as well as the reloading methods I have developed, and there is no way a bullet could be engraved in a way that damages it.
If I’m wrong, I wish someone would teach me different!
- July 6, 2016 at 1:51 am #28779oldblinddogParticipant
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It’s a hypothesis, not a theory. A theory is proven. Based on what I have seen and read you are almost there, however.
- July 6, 2016 at 4:12 am #28781
If I seem frustrated, it’s not with the dissenters, bit with the problem itself.
I think about a way to prove or disprove this all the time.
My HV test box was very enlightening, but needed more testing.
im hoping that the new property will afford me the opportunity to do exactly that.
I wish I could settle it in my mind once and for all.
Theres got to be a way to expose the root cause of this, and I can’t help feeling that if I knew where the problem existed, I might be able to find one more solution that will make it that much easier to shoot cast lead bullets quick and precise.
I just wish I had a few more theories that encompassed all the points given above, but unfortunately, mine is the only one that attemptes to offer any sort of detailed explanation.
I don’t have any hidden agenda or secret information, so if any of you savvy fellers have an idea, by all means post it here!!!
I don’t have an axe to grind here. I’m looking for the truth of what really happens dynamically that causes the bullets to suddenly lose their grasp on linear dispersion at a certain RPM for a given caliber, bullet style, allot etc etc etc.
im willing to consider everything but little green aliens at this point. All I ask is that a postulated theory not require willful ignorance of the obvious facts stated above. As long as it has a reasonable explanation for the evidence given, I very much like to hear it.
Ill openly my admit my theory, or hypothesis is unorthodox, but the fact is it’s the only one that gives it an unbiassed effort!!!
I’m not out to prove any particular method. Never was. I simply acknowledge the evidence provided by each method and I know that whatever the truth is, it must line up with all those known facts in order to be real.
I know that bullet alloy has some springback to it, I see it every time I push hard bullets through a sizer and they come out bigger. It seems reasonable to me that the same thing can happen in a torsional manner as well, and I think I saw evidence of it with my bullet catching experiments.
Is that the only possibility? Well, only if it’s the truth eh? If it’s not true, then surely there’s another idea out there that is.
Whoop it on me! How does a bullet get damaged when it’s touching the rifling, while leaving no evidence of it on the bullet? How does the same bullet survive identical condidtions or even harsher conditions when wrapped with thin paper? Surely if the bullet was imbalanced within a precision tube there would be SOME sort of evidence of it? Where’s the evidence? Throw me a bone fellers!!!
- July 6, 2016 at 5:54 pm #28789
The RPMTH is real!
I have several loads that I worked up last winter and was using them to fire form some cases. But with the seasonal changes, (temperature increase) now I’m getting dreaded “minute of berm”. The downer is that I’ll have to wait another six months before I can finish fire forming these cases! Lesson learned: Seasonal loads!
- July 6, 2016 at 6:37 pm #28790
Seems to me you need a Striker or XP100 cut bak to an inch or so past the OAL of the Cartridge. This would allowyou to see only what is happening in the first inch .
I have seen validation of the Rev theory with jacketed bullets. I have an 06′ that doesn’t exist built by Savage with a 1-8.5 twist. 150 at 2600 fps will drop 5 overlapped, 2650 it becomes 5 touchingby 2690 the group is an honest inch at 2710 it’s out to 4″ . By 2800 fps the pattern is best measured in ft.
With heavy cast using “normal” means alloys and powders I get to about 1800 fps before it falls apart. Sense this is a pure hunting pursuitrifle no super hard alloys were tried. .
As I take a step back I have a mildcat and a standard of very similar cartridges. . The 6.8 SPCII AR graciouslyallows me to use standardfor cartridge powders with little to no prep and launch the heavy for cartridge bullets that meets or exceeds jacketed speeds and accuracy which isn’t brag worthy. It also gets me into the 220s pushed checked 75/25 WW,-1/20 with a best guess of 41 kpsi . I really wanted to whack a pig with the rifle this year but it didn’t work out. Moving on the bullet was designed for this chambering and it’s a zero round barrel,all bonus points .
The 7×6.8 mildcat has been interesting and been side lined for a bit . It is a 1-8.5 and provided good consistency but I haven’t been able to explore it’s full weight potential due to personal stuff . I can conclud nothing at this point from it.
You’re on the right path . The solution for the merging proven data is at hand but I suspect that it will demand a trade off like all things do.
- July 6, 2016 at 6:52 pm #28791
uber7mm;n8003 wrote: The RPMTH is real!
Of course it is. You’d have to be shooting with your eyes closed not to recognize its inherent validity. What no one has been successful in answering (unless my hypothesis is correct) is WHY THE RPMTH EXISTS. What is it that produces this effect? It’s a real jawbreaker of a question, and it’s something that I want to understand better. I accept it as a fact, but having no explanation is frustrating. I’m giving it my best effort to find out though.
- July 7, 2016 at 1:30 am #28794
Yes, eyes closed, or in denial, as you previously stated.
- July 7, 2016 at 1:58 am #28795
Thinking out loud….
If lead, say a WW bullet has a particular RPMTH, and hardened lead, Linotype or Lyman #2 has a faster RPMTH, as do Paper Patched and jacketed bullets, (jackets being the fastest). Being that Paper patched and jacketed are protecting the soft lead core, RPMTH seems to correspond to the hardness of the projectile (and other factors), with a deforming of the bullet, deteriorating accuracy as the possible cause of RPMTH. Tim expressed is more eloquently above.
My questions are:
What is the RPMTH for a solid copper bullet?
What is the RPMTH for a solid brass bullet?
(The RPMTH for a solid brass bullet should be higher than copper, being that brass is harder than copper.)
What is RPMTH of a steel core bullet?
- July 7, 2016 at 4:33 pm #28801
There are plenty of barrels that have the twist to seek a rev related bullet failure. Just grab a 1-7 or 223 barrel for a Savage and ream it for 22-250 or even swift and let it rip .bot should reach 4000 fps with 55 gr bullet or well into the middle 3000s. Repeat with a 300 RUM on a 91/30 at 3000+ with 150 gr bullets. Trouble is its comparing different shapes, to different densities. And each will behave differently. To copper a GMX to TTSX is only close a 301618 is close to an XCB give or take 25 gr.I supposea RNSP would be close to a 301618 or maybe a full Spitzer . But where do you get a 30 cal solid in copper or bronze.? Umm they’re all different lengths. That alone changes the outcome. I doubt very much that there is a steel core or jacketof that design .
We add to this the complexity of different powders and pressure to reach the needed speeds and wow so.e will be happy down low but walking the razor at the top and the reverse is true to. This conquersonly rev velocity on paper and does nothing to address the cast the exits the 302×314 barrel at 301
Or do we look for the weight length values only in reaching solution for just revs. I mean you’re looking at a 300 gr cast but a 225 gr copper/bronze and maybe as light as 190 gr for a copper washed steel . Seems to me that these would need to be turned bullets just for grins let’s throw in DU now you have a steel like bullet that weighs over 400 gr in a 30 cal projectile.
Just the logistics of a base line comparison makes my head hurt. Just to sort out 1 single facet of the quest.
- July 7, 2016 at 6:38 pm #28803
Good point Harter,
It really needs to be an “apple to apple” comparison.
- July 7, 2016 at 10:15 pm #28804
With my 1-8.5 06′ that doesn’t exist ,I’m told that often. ,I shot a single bullet over Red Dot , Unique 4895 and 4350. The bullet would shoot wel up to about 1200 fps on RD, and up To 1400 on Unique 4895 would get me to 1600 and 4350 to about 1800. I had a ton of things working against me ,plain base spire point shape the loooonng Savage throat that is huge and a sub dia muzzle with roll stamp divots.
The interesting thing about the bullet is that it shot almost identical speeds of failure in an sks paper patched in a 305×316 barrel that will feed a Lee 323-175 2r sized 323.
Slower twist 3 inches more barrel half the powder space same results I doubt this is a qualified test but it’s data.
- July 7, 2016 at 11:22 pm #28805
It is indeed. Good stuff there Harter.
Sock it away.
Im still thinking that I need to shoot a Lovern style bullet way over the RPMTH and well under it, and catch both bullets in soft media at long range. I tried the wet sawdust thing with the XCB bullet, but all we discovered was that the bullets are hydraulically swaged down in front of the gas check by the lube.
The fact is, that wasn’t the best bullet to use for the test because I designed it very carefully to resist any sort of slump, or dishrag twist.
The 311466 is a different matter. It’s both an excellent cast bullet, but also has enough bearing surface to show “weirdness” if it exists.
The big challenge is to find a media that catches the bullets gently enough to cause almost no damage at all.
Could be the sawdust is still my best bet, but at longer range. The last test was done at only 85 yards.
- July 8, 2016 at 12:28 am #28808
How about chipped rubber used for playgrounds?
- July 8, 2016 at 2:07 am #28812
I’d jump all over that if I could get a pickup truck load for decent money. Takes a lot of media to do a test like this.
I’ll definitely look into it.
- July 8, 2016 at 3:13 pm #28817
Truckload? You’re such a good shot, all you’ll need is enough to fill a foot long 1/2″ pipe! LOL
Not cheap: HD isn’t giving that stuff away. (Or anything else for that matter.)
Since I wasn’t born into a rich family or handsome, saw dust or even soft dirt would be my first choice. It’s cheap and an easily sourced product.
- July 8, 2016 at 5:12 pm #28818
Very interesting Goodsteel, and the best synopsis of the different schools of thought that I have seen.
I have molds of your 30 and 35xcb, as well as some other HV contenders, but work and family have conspired to limit my casting and loading efforts with them. Add the current political climate and the priorities on my list of toys and things to feed them has been affected.
An ultra high speed camera would be the best way to answer the question of what happens when the bullet leaves the bore, but the cost of such a tool is probably prohibitive.
Here is a camera that can capture 640 x 480 resolution images at 1500 frames per second at a cost of $1500.
Not quite fast enough I would think, as a bullet traveling at 3000 fps would only allow a picture taken every 2 feet. However, if one fired many identical bullets and took pictures of each one, it might be possible to get many pictures within that first two feet and make some inferences.
- July 9, 2016 at 12:31 am #28825
That’s pretty high praise there Uber. Here’s the problem:
I could drop my bullets into a coffee can sized group at 200 yards with the bullets that were UNDER the RPMTH, but the test requires catching some that were going OVER the RPMTH. The latter are inherently inacurate which is the reason for this whole test. Those are the ones that really have me scratching a bald spot on my head trying to figure it out. At 200 yards, the group size could easily be 4 feet in diameter.
I’ve dicided the only way to do it is to construct a catch box as large as possible and just keep shooting till I hit it. (Sigh).
- July 9, 2016 at 12:47 am #28826
That’s what I came to as well Fishman. The cameras that are even close to being effective for the purpose are prohibitively expensive (heck, I wish I had even $1500 laying around).
Besides that, I don’t think it would help. I talked to one fellow who thought it possible to make a transparent barrel out of ceramic. That coupled with the $25,000 high speed camera could tell us volumes!!!
However, again, we’re talking about some serious coin.
I’m willing to go there someday, even if I find a way to rent a lab (that would be cheaper) but I think it would be wise to exhaust every possible simple test procedure if for no other reason than to make the most of such an investment when the time comes (if that makes any sense).
Besides, it may just be that a few carefully executed tests could tell us everything we need to know, hence the reason for this thread. If you fellers have any input on what a definitive test would look like and be constructed, I’m all ears.
My strength is in visualizing static mechanisms. I’m a pretty fair hand with dynamic events, but it’s aweful easy to miss the mark in that regard.
I want to figure out how to run tests that trap the data so we can eliminate what is definitely not happening, the result of which will be a fairly clear idea of what is happening by way of the process of elimination.
- July 9, 2016 at 5:25 am #28830
Yep, I get the over RPMTH accuracy issue. (First hand in fact!!) A open 3 sided box of rail road ties to hold your catching media would work. I’ve seen like troughs at rock quarries to separate different sizes of gravel for sale.
- July 9, 2016 at 11:37 am #28833
One thing I don’t see in your analysis is a discussion of gas checks. Why would a checked design be more resistant to rotational forces than an unchecked design? We know that checked bullets of the same alloy can be driven faster than unchecked and maintain accuracy. How does that fit in with the “twisted bullet” hypothesis, or does it? All of the twisting would occur prior to the check’s entry into the bore. Perhaps I am misunderstanding?
The coated bullets crowd points out that coated bullets can be driven very fast without a check with no leading, but accuracy goes away. Check it, and accuracy returns. I wondwr how might this yield some insight, as it is a different result than conventional lubes, where leading occurs before 2000 fps in most cases if checks aren’t used.
- July 9, 2016 at 2:13 pm #28836
Fishman;n8052 wrote: Fair enough.
One thing I don’t see in your analysis is a discussion of gas checks. Why would a checked design be more resistant to rotational forces than an unchecked design? We know that checked bullets of the same alloy can be driven faster than unchecked and maintain accuracy. How does that fit in with the “twisted bullet” hypothesis, or does it? All of the twisting would occur prior to the check’s entry into the bore. Perhaps I am misunderstanding?
The coated bullets crowd points out that coated bullets can be driven very fast without a check with no leading, but accuracy goes away. Check it, and accuracy returns. I wonder how might this yield some insight, as it is a different result than conventional lubes, where leading occurs before 2000 fps in most cases if checks aren’t used.
Gas checks are a given, and they have no rotational allegiance to the bullet whatsoever. They go where they are told to go no matter what.
I once pushed a heavy cast billet with a short bearing surface past 2000fps with a faster than should have been used powder, and I recovered a bullet that had almost stripped the riflings. The lead impressions of the grooves was cut to about .010 wide while the impressions of the lands were almost double what they should have been. Definite skid happening. The curious thing was that I recovered one of these that still had the GC attached just as it had left the barrel. The rifling marks on the GC were full compliment and perfectly proportional. It did exactly what it was supposed to do, and maintained a perfect gas seal, even though the bullet ahead of it was skidding. Basically, the check has no ability to maintain its radial location on the base of the bullet, and why would we care if it does or does not?
OK, moving on to the sawdust tests with the XCB bullet at nearly 3000 FPS: all the GCs were lost on impact, but the bullets were perfectly engraved by the rifling and no skidding was observed. Bullets like the 30XCB, 35XCB, and 311466 have so much bearing surface vs the mass of the bullet, skidding is non existent, unless the entire surface of the bullet skids around the core, which is unlikely, but nothing I’m throwing out as a possible cause/contributed of slump and/or the RPMTH.
Throughout all of this though, the GC remains plastered against the base of the bullet as a bulwark between the force of expanding gasses from the rear and the resulting resistant inertia from the front. If there’s one component we’ve got here that has absolutely nothing to do but it’s job, it’s the GC. In fact, the harder you push it, the more effective it is.
Another thing I’ll say about the GC is that it is a harder material than both the gas behind and the lead in front. Therefore both will conform to its shape, and it will emerge from the barrel close to the shape it entered with.
This is why I recommend uniforming the GCs if you’re after high performance. If you seat the GC in its natural potato chip shaped condition, and do not have a perfect mate with the base of the bullet, two things will happen.
1. The base of the bullet will conform to the shape of the GC (not the other way around as some think) and
2. The weak areas between the check and the bullet will get lube swaged into them because the hydraulic pressure in front of the GC is also stronger than lead (even Linotype or #2).
I say all of this simply to say this, and I say it most emphatically:
If your GCs are not seated square to the driving bands with a perfectly flat bottom and the bullet they are seated on does not have the same qualities in its own right, the bullet base condition will not get better through the act of firing, and the more precision/speed you expect from these bullets, the more vital it becomes to get this right!!!!
I’m not saying we need to break the bank and think deep thoughts, and meditate here. All I’m saying is that the base of the bullet matters more than any other feature, and when the GC is seated on the bullet IT IS THE BASE.
Bust open a new package of GCs. Take one out and look at it. Take a ruler and lay it across the bottom of the check and see if you can see any light. Ask yourself: “is this flat?”
Then take one of your bullets that has the check already seated and put it on a precision square. Watch for light between the beam and the driving bands. Ask yourself “is this square?”.
If you do this, and you can not answer in the affirmative on both tests, then you need to fix your process so that you can.
That’s the whole point of my method for uniforming GCs and why I made the lube pens, and all kinds of other stuff that allowed me to answer those two questions in the affirmative.
More to the point of your question, obviously, we do not put GCs on bullets to combat rotational inertia or torsional stress, or anything else because a much bigger problem manifests itself before we ever get to these higher pursuits: gas cutting.
With an air rifle, you can’t push a projectile any faster than about 1300 FPS, because compressed air just doesn’t have the required strength to provide any more than that.
Lead has its material hindrances also. It simply cannot contain pressures required to push faster than about 1500FPS (often less) without the seal with the barrel being compromised.
If the seal with the barrel fails, then leading and horrible accuracy will be the result. The GC is simply a gasket that provides a barrier between the bullet and pressures behind it that far exceed the pressure necessary to turn even the hardest lead into silly putty.
That’s why the GC is a given in any HV discussion.
- July 9, 2016 at 5:05 pm #28838AnonymousInactive
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I’m not able to contribute to the mainline discussion here, but may have a worthwhile suggestion for capturing bullets — including fairly wide grouping ones.
After a lot of research, I made a lead-bullet catcher based on the Home-Depot-bucket design and have caught some pretty nice condition bullets of very soft lead with it. It’s pretty cheap to make and is semi-portable. With a 13″ wide capture area, it might be something that fills your need for catching good-condition bullets even when they are inaccurate. It certainly beats the dirt berm alternative I have for catching and making comparisons.
I used 4 plastic buckets, all of which are filled exactly to the point where they can be pushed/compressed into each other solidly, yet have no air-gap between one bucket bottom and the next bucket’s filler material. The buckets fit together tightly, so they try to stick together from suction if you try to pull them apart while standing on their bottoms. The front bucket has a standard plastic lid that is easily replaced as it gets shot out. With the higher energies you will be hitting with, you may have to tie the buckets together — easily done by lashing the first and last handles at their attachment points.
The first bucket is filled with heavily compressed WalMart rubber mulch, the 2nd with about 6″ of the same, the third and 4th each with about 6″ of fine sand. At the meager velocities I shoot, nothing has got past 2/3 of the mulch in the first bucket, and according to the bullet penetration information I’ve been able to find, with the 12″ of compressed sand on the end, the combination should be able to stop pretty much anything. Then again, if something should penetrate the first two buckets so far as to get into the sand, the velocity by then should be low enough so the sand doesn’t abrade the bullet too much.
When put together, the 4 buckets are heavy but make a single very solid unit. I use a couple of heavy-duty saw-horses to hold the thing up.
Do please keep this thread alive. The analysis is appealing and experimental results will be interesting.
- July 9, 2016 at 5:39 pm #28839Bodean98Participant
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I have been using some of the industrial totes (250 gal.) filled with sand as bullet stops. I cut the top on 3 sides to open it up for filling. I am still on the first side for shooting and there have been upwards of 4000 rounds into it. It is still holding strong and there are three more sides to shoot at.
Perhaps you could fill one with water and shoot it at 200 yards to catch your boolits for examination? They offer a large target area, approx. 3.5 feet square and are relatively easy to hit. The boolit holes do not completely heal and would leak water but would plug with clay or some such for more shots.
They make a really good backstop.
- July 9, 2016 at 6:33 pm #28842
Goodsteel, thanks for the clarification re: gas checks. Really an excellent thread. I will think some more on this challenge.
- July 9, 2016 at 9:52 pm #28843popperParticipant
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entire surface of the bullet skids around the core,
From some static twisting tests I did few years back, that is possible. I twisted until fracture many 165RD and observed a very unusual pattern in the break. Boolits got longer, always broke at the front edge of the L.G. and had ‘rings’ of stress patterns. 1/3 of radii was rings of shear (clean break) center was very crystaline and rough break. Same test on #2, Roto high Sb, AC or WD. WD caused the slip region to grow and fracture region to shrink. We/I don’t know the flexure that results from stress weakening of the alloy. Arrows wiggle a lot then shot, perhaps our boolits do also.
- July 10, 2016 at 3:31 am #28845
Honestly popper, you’re comment is absolutely spot on with my observations.
Arrows do indeed demonstrate that enormous dynamic effect can occur on s projectile that rights itself in flight, even when only mediocre stresses are involved.
- July 10, 2016 at 3:45 am #28846
Catching bullets at these speeds is extremely difficult gentlemen.
The bullets are going so fast, they are swaged down in the barrel by the lube residue itself.
The bullets are shredded and mushroomed by wet sawdust. They splatter when they touch water. Sand is a good way to turn a HV bullet into something that looks like a silica crusted meteorite.
This is why the 200 yards is key, and also why I’m looking for something that is easy on the bullet but large in size filled with something gentler than sawdust.
The hope is that the bullet can be slowed down to less than 2300FPS in that distance (which is still faster than most folks have shot 30 caliber cast bullets with any semblance of precision.)
The rubber is a great idea, but expensive in large quantities. However, my buddy JT is the scientist at a local tire bladder facility here. I’ve seen him come home with a pallet of 3/8″ thick raw rubber he said weighed one ton.
I kept thinking about shooting that stack, and he was thinking of using it as a backstop, but it was too dense to catch bullets without damage. Like ballisic gel only twice as hard. however, if dude can get shredded rubber???
Ill have to ask him.
The industrial totes sounds like a superb way to provide a large target area though.
Even if I can’t get the rubber mulch, I wonder about filling those bags with ceiling insulation, and stacking them two or three deep?
I think if I could stop the bullet in 50 inches, I’d have it by the tail.
Great suggestions gents. I’ll see if I can find an angle I can put together.
- July 11, 2016 at 2:35 am #28855Wright ArmsParticipant
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My experience with capturing lead bullets is quite limited, but I have already made an observation or 2. For 1, even a hard lead bullet (22 BHN) of .35 diameter and 200 grains in weight traveling at relatively moderate speeds (2300 FPS) will essentially disintegrate in less than 33″ of water. And a bullet of the same diameter, (.35″) weighing 160 grains and travelling roughly 1500 FPS will penetrate the same 33″ water column along with more than 6″ of Midwestern terra firma and become essentially unrecoverable.
I do not pretend to understand exactly why this is happening. I can only tell you this is what I have seen, and therefore, capturing lead bullets fired at high velocity undamaged is going to be quite a trick. Not that I think it is impossible. I look forward to seeing the solution. I have no doubt it can and will be done.
I have tried rubber mulch to a limited degree. After reading this thread, I will experiment some more and report my observations once again.
If the 200Yd range has been suggested to drop the velocity range to the point recovery is more likely, may I humbly suggest 500 yds is a more likely range to accomplish the desired velocity reduction? Not at all easy, but you all are shooting hard cast extremely fast. It blows up at high velocity, and punches thru most anything at lower velocity. You all have your work cut out for you. IMHO.
- July 11, 2016 at 3:16 am #28857
So you want me to shoot bullets over the RPMTH at 500 yards?……and actually hit something?
If that were possible, there would be a lot more targets posted in the three caballero’s laughable HV thread.
Even if I filled a barn with soft rubber mulch and shot at it, I’d only hit it if I shot a bazillion bullets at it, and even then, it would be like looking for a needle in a haystack.
That’s the reason for the "short" range.
(I say short. That’s about 97 yards further than any sombrero will shoot while keeping his meager ration of honesty intact. With the finest HV cast rifles ever built no less.).
No, I feel that hitting a 500 yard target would be very doable, but only with a slow twist barrel and a very specific set of loading parameters. Then it would be easy, but there’s no way you’re going to do it while pushing over the RPMTH, and if you don’t shoot over the RPMTH, the whole purpose of this test is a mute point.
We know what works. I held the nails to the lid of the coffin while Larry and Bjorn hammered them in.
What I want to know is exactly what is it that the slow twist barrel has such a profound effect on.
In order to do that, I’ve got to know what the exact cause of the trouble was in the first place.
I keep wondering, if I knew what the cause was, if I couldn’t find another way to get around it, or to improve on what has already been done.
- July 11, 2016 at 5:32 am #28858Wright ArmsParticipant
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I do not dispute the difficulty of arresting high velocity cast in any way. I merely wanted to point out that it seems unlikely that a cast bullet can be recovered without using plain old atmosphere to slow it to a recoverable velocity intact.
- July 11, 2016 at 10:28 am #28859
Wright Arms;n8077 wrote: I do not dispute the difficulty of arresting high velocity cast in any way. I merely wanted to point out that it seems unlikely that a cast bullet can be recovered without using plain old atmosphere to slow it to a recoverable velocity intact.
You could be right. I still think it’s just a matter of catching it.
Say you jumped out of an airplane with a defective chute, and you’re plummeting towards earth. You’ve already siad your prayers and you start looking for s place to land. Like the bullet, you now need to arrive as unmangled as possible.
Suddenly you spot a few silos like are used for grain. They have no roofs on them.
One is filled with playground balls.
One is filled with foam peanuts.
One is filled with sand.
One is filled with water.
One is filled with grain.
One is filled with dryer lint.
Obviously, you’re going to whip out your Schmart phoghne and try to determine which media will stop you about 1foot from the bottom of the silo, because how quickly you decelerate has a very real effect on how much damage is done to your body.
Im looking at the bullet catcher the same way.
I suppose that the depth of penetration can be used as a direct measure of how gently the bullet was caught, given a homogenous catch media.
I got roughly 36-40 inches of penetration from the wet sawdust, and bullets caught were intact from the base up to the ogive. The nose was gone, and the bullet was trying to mushroom. I’m thinking that if I can extend the depth of penetration to 7 feet by using a softer catch media, that will do the trick.
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