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    • #34752
      Waksupi
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      I have a few pounds of the square flake Turk powder. I’m thinking of using around 42 gr., for a velocity of around 2450 fps in my .375 H&H. That load leaves quite a bit of space in the case. I’m thinking WC 860 or WC 872 as filler. Anyone see any downside?

    • #34753
      Harter
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      I’m just here to watch .

    • #34756
      JPHolla
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      I recall someone doing this with no adverse effects but don’t remember who.

    • #34758
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      I remember that from CB something like 4895 as a primary and W857 .

      Something about a “nert” filler or not inert filler …….It was in the thread title .

    • #34759
      Goodsteel
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      It was Nobade who was doing this IIRC.
      Personally, I think it’s dangerous to consider mixing or duplexing powders (I’ve done some of it, and I decided the juice just wasn’t worth the squeeze) but it’s unlikely that anything would go wrong, and for an experienced gunsmith like yourself, you know how to take precautions.
      To anyone in the future reading this, DO NOT ATTEMPT THIS. Waksupi is an extremely experienced professional and a little crazy to boot.:cool:

      50MBG and cannon powders are simply too slow to be of any earthly good to a medium/small cartridge (theoretically), so the thinking is to fill the extra case capacity with powder that is too slow to cause any pressure spikes, but it will burn a little, and theoretically produce the same effect as if the case was 100% filled with a powder of proper burn rate for the application (which doesn’t exist which is why we would look at this in the first place). In theory, It’s a dynamic filler.
      Ric, if you’re bound and determined to try it, at least use a rifle you don’t care deeply about and strap it to a lead sled and step back with a 10′ string. Violating the first rule of gunsmithing at your age is a positively insulting way to kick off.;)
      That said, it should be fine……..theoretically………at least until something changes……..

      I was messing around with propellants once and I was seeing my speeds over the chronograph gaining 50-100fps with each shot. I would shoot at least 100 rounds over a chronograph in varying temperatures just to make sure you’re on solid ground, and if everything is predictable, and there are no strange spikes in speed, then you have to ask if the juice is worth the squeeze, and that’s usually when I quit messing around and go to standard reloading data even if I have to shoot jacketed bullets. I’ve never seen a duplex load that brought so much advantage to the table that it was worth the misery invested and the open invitation to Mr. Murphy.

    • #34763
      Rattlesnake Charlie
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      IIRC, Larry Gibson has experience in this arena as posted on “the other site”. I’m hoping to get into this territory with some .45-70.

    • #34767
      Screwbolts
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      IMHO, It is my thoughts that the current charge of powder will act more than a Kicker. The 42 gr of Turk will raise the pressure up in the case to allow for a complete burn of the 860 or 872, thus the 860 or 872 are not simply be filler but rather will add substantially to the pressure of such an experiment.

      I have used both 860 and 872 in my 50 BMGs they burn/perform well in that cartridge.

      Be Safe,

      Ken

    • #34774
      Larry Gibson
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      Waksupi

      What bullet?

      Larry Gibson

    • #34831
      Waksupi
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      I’m using a 285 gr. MOE mold. I do know a .375 H&H will stand a lot of pressure, just want to make sure I don’t get carried away, one way or the other. Maybe I should load up a bunch, send them and the rifle to Tim, and if it comes back with empty cases and no blood, they would be good to go.

    • #34833
      Goodsteel
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      Oh, I’m THAT guy huh?
      Dang.

    • #34847
      bjornb
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      Here are my $.02, having done my share of duplexing experiments, both with black and smokeless. This is how I would have gone about the load workup: Assuming the Turk powder is similar to WWII 8mm Mauser powder, I’d start with 10 grains as a kicker, then pack the case full of the Milsurp. 860 or 872, very small difference considering the job you are asking the powder to do. Shoot the load over a chrono, then check speed, unburnt powder and pressure signs. If the load is a dud (1500 fps or thereabouts), start increasing the kicker by 5 grain increments while checking the same items. 2-3 rounds per load is plenty. It’s as safe as you can get while duplexing.

    • #34849
      Waksupi
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      So far, I’ve gone to 10 gr. Turk, with the filler being WC860. Velocity is around 2050 fps. According to theory, I will only need another 8.5 gr. Turk to reach the minimum velocity I’m looking for. I’m starting to believe I’m over thinking this, and am probably perfectly safe reaching for where I want to be.

    • #34850
      Larry Gibson
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      I could give Bjorn’s method a try and pressure test along the way possibly working up to Waksupi’s load as I have some Turk pull down powder from 8×57 Turk. However, I don’t have any WC 860 or 872……

      Larry Gibson

    • #34855
      bjornb
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      I’d be very interested in seeing the experiment with the 375 H&H; it’s not a cartridge you get to play with very often. I’m checking now to see if the powder is available anywhere near Larry.

    • #44956
      Larry Gibson
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      Duplexing Turk ’43 and WCC860 in the 375 H&H

       

      In considering whether to test a 375 H&H duplex load (I value my M70) I gave it some thought. I had not really considered duplexing before as I’ve not invested in the really slow burning powders so had no need to. Also I’ve so many test irons in the fire it wasn’t on the top of my “to do” list. However, Waksupi’s thread here and on goodsteelforums.com peaked my curiosity. In thinking it over I relied on my own experience with BP duplexing and previous post on the topic by Novade. I found a duplex BP load, if done correctly, to be quite safe, useful and accurate. I saw no reason why it couldn’t be done with the powders Waksupi was wanting to use. My standard 375 H&H load uses 300 gr jacketed bullets (Hornady 300 SPBT, 300 RNSP and the 300 FMJ) over 78.5 gr of AA4350 in NS’d R-P cases sparked by WLR primers. They ran 2570 fps at 57 – 58,000 psi when I developed the load in Washington 7 or 8 years ago. Thus I concluded using 5 gr of the Turk powder with 75 gr of a slower powder than AA4350 (WCC860) on top of the Turk ’43 powder under a 287 gr cast bullet should be “safe”.

      I had the 375 H&H already with a strain gauge on it for pressure measurement, I had pulled down Turk ’43 powder and all I was missing was the bullets and some WCC860. Waksupi sent the bullets and Bjorn souveniered me some WCC860. I loaded one of Waksupi’s PC’d NOE 378-279-FN bullets in a split necked case to check seating depth in the test Winchester M70. Turns out they fit quite nicely in the case neck.

      Being able to see the bottom of the bullet in the case gave me the correct load density needed to prevent migration of the powders. Waksupi also said he used a small tuft of Dacron on top of the powder for the bullet to push down on as “insurance”. I decided to do the same. I then loaded a round with 5 gr of the Turk ’43 over the primer and then filled the case with WCC860 to the base of the bullet. I then weighed both charges and subtracted the 5 gr. That gave me a charge of 75 gr WCC860 to start with using 5 gr of Turk ’43.

      For the psi work up I had to figure how much to reduce the WCC860 as I increased the Turk ’43 powder I then filled the same case to the same level with just WCC860 and weighed that. It came to 81.5 gr. So basically 6.5 gr WCC860 equaled 5 gr of the Turk ’43 powder. I decided on increasing the Turk ’43 powder 3 gr per test which meant a 2 – 4 gr reduction (I was cautious at first so went with 2-3 gr changes) of WCC860. I was hoping to work up to 2500 fps or where accuracy went erratic before pressure became an issue.

      I did size Waksupi’s bullets at .377 and lube them with Lar’s 2500+ as my experience previously with other PC’d bullets indicates lubed PC’d bullets are more accurate and do not foul the barrel. To test Waksupi’s initial load I loaded 8 rounds of 5 gr Turk ’43 with 75 gr of WCC860 on top. Then a small tuft of Dacron was inserted and the bullet seated on top of that. I then loaded 14 rounds for the psi workup loading 8/72 (Turk/WCC860) through 47/27 (Turk/WCC860) gr in the increments listed on the Oehler test data sheets.

      With all that done last Tuesday I loaded up all the Oehler M43 accouterments and was off to the range. It did not go well. I shot 2 rounds of Waksupi’s load and knew the strain gauge had apparently cracked. So it was load everything back up and head home……

      The last couple days I double checked everything on the M70. Sure enough the strain gauge had cracked. As it had been on for 7 -8 years and a lot of heavy recoiling rounds had been fired a couldn’t really complain. Yesterday I put a new strain gauge on. It is a procedure because it is permanently affixed. The old gauge had to be completely removed down to bare metal, the barrel metal prepped, the new gauge prepped and then glued on, then the leade wires attached. After that I hooked it up to the M43 and computer and all checked out. All appeared well. However, only shooting can tell if it’s really good to go.

      Woke up at daylight this morning and the temperature was only 78 degrees and the wind seemed manageable so I loaded everything up and headed to the range. Set up went smoothly and the new gauge checked out. The rifle is a Winchester (New Haven) stainless M70 375 H&H. Scope is a Leupold 1.5x5X with duplex reticle.


      I then set up to shoot the remaining 6 rounds of Waksupi’s load. Target was at 100 yards. 1st shot out of the clean barrel went high left. The pressure was 37,500 psi at 2078 fps. The pressure trace looked fine. I then shot the remaining 5 shots which went into a nice 1.9″ group. Looking good with no problems so far.

      Muzzle velocity averaged 2096 fps for the 6 shots with an average psi of 38,000. The SD and ES for velocity and psi were excellent. If you look at the rise of the pressure trace you can see where the pressure eased a bit as the Turk powder burned out and where the WCC picked up by itself.

      The PSI workup

      I then ran the 14 shot psi workup test of increasing the Turk ’43 powder while decreasing the WCC860 powder. The charges were from 8/72 (Turk/WCC860) through 47/27. All went well with relatively smooth pressure traces. Looking at the pressure rise of each increase/decrease of Turk/WCC860 we see the slight psi drop off decrease as the amount of Turk ’43 is increased. Looking at the target you can see where each round hit. Six rounds, 8 through 13 hit into a very nice group right at point of aim. Rounds 11, 12 and 13 hit the magical 2500 fps. That is very equal to factory 300 gr 375 H&H performance. I will load 10 shot tests of loads 11 and 12 to test for a more complete pressure picture and for group. If either does well that would be an excellent load for anything walking this continent……..

       

      It would appear that duplexing with these components is safe. Is it safe with other components……I don’t know and won’t conjecture. However, since the Turk powder is very close to 3031 and H4895 I will load a test string substituting H4895 for the Turk ’43 powder, probably load 11.

      Be safe.

      Larry Gibson

    • #44959
      Larry Gibson
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      I completed the Turk/WCC860 duplexing test a couple days ago. Based on the previously posted psi workup and projected further tests I loaded 7 rounds of 26/50 (Turk ’43/WCC860), 8 rounds of 32/42 and 8 rounds of 38/36 to get a better idea of the internal ballistics and the accuracy capability. Waksupi’s bullets were used and a small Dacron filler was used to assure some compression. I’ve no idea of the alloy Waksupi used or the PC method. He stated in a PM the bullets were “seconds”………if so they did pretty darn well…..

       

      As before the fouling shot with the 26/50 duplex load was a wide flyer, exhibited the lowest velocity and the lowest psi. The other 6 gave an ES of only 16 fps and only 1,700 psi ES. The smooth pressure traces show it is and excellent load though we can readily see where the WWC860 “kicked in”. Accuracy was excellent for the 6 shots; right at 2″. Considering the muzzle velocity was 2339 fps right at the RPM Threshold for a 12″ twist I’d be confident hunting with this load.

       

      The 32/42 duplex load demonstrated excellent internals with and ES of 24 fps, and SD of 8 fps and a psi ES of only 2,600 psi. However, exceeding the RPM Threshold at 2400 fps muzzle velocity was evident because even though the internal ballistics were excellent on the external ballistic side accuracy began to suffer. The group size increased to 3″.

       

       

      With the 38/36 duplex load again the internals were excellent; ES of 20 fps, SD of 7 fps and a psi ES of 1,900 psi ES. The accuracy again suffered at 2.6″ group given a muzzle velocity of 2481 fps but one of those shots should have been much further out to the left as I called the shot. As it was it went to the middle of the group…..that happens sometimes with ammo that produces larger groups.

       

       

      Obviously many if not most of you with WCC860 probably don’t have pulled down Turk ’43 powder. So I ran another test using IMR 3031 and 4895 instead of the Turk ’43 powder. I used a duplex load of 32/43 with each of them. The IMR3031/WCC860 duplex load performed the best accuracy wise as 9 of the ten shots stayed in 2.75″ at 2395 fps which is just over the RPM Threshold. The 4895/WCC860 duplex load rand 2422 fps and the over 3″ group showed it exceeded the RPM Threshold also. Neither of these 2 tests using 3031 or 4895 had the excellent internals as did the duplex loads when the Turk ’43 powder was used. Their internals weren’t “bad”, just not excellent.

      That used up all the bullets Waksupi sent me to test and all the WCC860 Bjorn gave me.

      I flinched one off to the left with each of these last test loads as after 43 such 375 H&H loads off the bench I was a little “punch drunk”….felt like I’d been tag teamed by Ali and Frazier……..

      None the less I finished with one more test string just to test my own shooting ability, the instrumentation and the rifle’s (M70) accuracy capability. Thus I let the barrel cool, cleaned it and then shot a 9 shot string of my Hornady 300 gr hunting load. This was loaded in Winchester NS’d cases, WLR primers, 78.5 gr AA4350 with the bullet seated to the cannelure groove and a crimp applied with a Lee FCD. At 2612 fps it definitely lets you know you’ve pulled a trigger when shooting off a bench. The 9 shots went into 1.6″…..not to bad for being that punch drunk………

       

      Larry Gibson

    • #45012
      Goodsteel
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      Excellent post Larry. As usual!!!!

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