- January 30, 2016 at 1:06 am #22298GoodsteelKeymaster
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If you are thinking that loading cast boolits is a little different than loading jacketed bullets you are right! This is a totally different deal. The good news is that this is relatively simple once you understand what needs to happen and why. It’s just that you can be an expert reloader with jacketed bullets, without realizing that you are taking a whole slew of things for granted that you must control individually with a cast bullet. These same things are necessary with a jacketed projectile, but the extreme hardness of the bullets, make a lot of this a mute point, to the detriment of performance on the intended target. It has taken me a while to give up on my jacketed bullet crutch, but I have finally come to the conclusion that there is nothing that a jacketed bullet can do, that a cast bullet will do even better at 75% of the speed, except long range hole punching. If you can find a way to deliver a cast lead bullet to the target, it will out perform a jacketed bullet every time, but getting it there takes a little…..savvy.
You need to know the bore diameter and the groove diameter of your rifle.
In order to get this precise information, it is necessary to slug your barrel, and possibly use a pin gauge set.
In order to slug your barrel, get a pure lead slug (a fishing egg sinker works well for this) and drive it through a clean, oiled barrel, dropping it on a soft cushion like a T-shirt or a rag of some sort. Measure the OD to get your groove diameter. If you have few enough grooves, measure between them to get your bore diameter, or use precision pins in the actual barrel to get your bore diameter.
Next, you need to know what your chamber is like, and have a measurable rendering of the throat, free-bore, and neck of your rifle.
You can achieve this several ways, but the best is a chamber slug, followed by a cerosafe casting.
In order to get a chamber slug, take a once fired piece of brass from your rifle, and fill it with molten lead to just below the case mouth. Cast a lead boolit of pure lead. Insert the lead boolit into your breech, followed by the lead filled casing. Close your bolt on the casing. Take a 5/16 rod of aluminum or brass longer than your barrel, and put it down the muzzle until it touches the pure lead boolit. Use a hammer to pound the rod until it bounces, indicating that the lead has flowed everywhere it can and has filled every void. Carefully, open your breech and extract the lead filled cartridge casing. Give the rod a few light taps to dislodge the chamber slug from the breech. Measure it to determine the profile of your neck to throat transition, the throat diameter, and the length of the free-bore if any.
Edit: for more detailed information and pictures on how to do this operation, see this link:http://castboolits.gunloads.com/show…o-a-pound-cast
Now, your boolit should match these dimensions.
First of all, the nose of your projectile should be exactly the same as your bore diameter, or no more than .0005 less.
Second, the driving bands are to be .001-.002 bigger than your groove diameter, unless the free-bore of your rifle measures bigger than the groove diameter, in which case the bullet’s driving bands are to be .001 less than the diameter of the free-bore.
If your rifle has no free-bore, and all you have is a tapering lead-in, (aka throat) then the boolit must be .001-.002 larger than the groove diameter of the barrel, and the forward-most driving band should have an angle that compliments the throat angle, and should not protrude from the case mouth far enough to crash into that angle. A chambered cartridge should make the driving band just kiss the throat angle with perhaps .001 press upon closing the action
(Edit 9/10/15: the Hornady bullet seating depth gauge is an absolutely invaluable tool for finding this specific dimension http://www.hornady.com/assets/files/…OAL-Gauges.pdf Just seat your cast bullets to the depth the gauge gives you).
Now, your brass should be as long as it can be without crushing the case mouth into the end of the chamber. Your neck should stop just .001-.005 short of bottoming out in the chamber.
Load a dummy cartridge to these specs, smoke it with lamp black, and chamber it. You should see the lands wipe shiny streaks on the bore-riding section of your boolit, and leave shiny marks around the perimeter of the first driving band. Obviously, the cartridge should chamber easily. If you have no contact in these areas, do it over with a longer dummy till you find that spot. Don’t quit until you have this right.
It may require mold modification or brass modification or even new brass, or a new mold, but that does not change the fact that it must be this way, but you are working on becoming an expert reloader, so this should be no problem.
Once you have these things right, pull the bullet as gently as you can from the casing and measure the OD. If it is not .001-.002 over the groove diameter blah, blah, blah, make or have made, a neck expanding tool, or buy a Lyman M die so that your brass will quit squishing the bullet down undersized. Once you have this taken care of, reload the dummy, smoke it and do the whole cambering thing again.
Once you have things going your way on every last one of these instructions, load up ten dummies, smoke them and cycle them through your magazine/tube/etc etc and cycle them as you normally would. Observe if they are consistent in all these critical points. If they are, do it for real. Load up 10 rounds and shoot them. Don’t worry about accuracy for the moment, just load ’em somewhere in the middle and blast them off and see what your barrel does. If you get leading,(which I doubt) use a harder/tougher alloy like 94/3/3, or water quench your bullets to get them a touch harder.
Shoot again. You want a smoky looking barrel with a little bit of a lube star on the muzzle and NO LEADING.
Load 10 cartridges each, in each charge 1/2 grain at a time, minimum to maximum. Each charge is a law unto itself. The one merit that shooting a ladder has in this case is that you can easily determine when and if your lube fails, but you’ll know it either way, so I just do 5 shot groups till I’m pretty sure I’m on a node, then I go to ten shot groups.
This is the best I can do to explain how to get the most from cast bullets.
I hope this helps somebody get where they are going.
- February 6, 2016 at 1:45 pm #22957Went2kckParticipant
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Nice write up on using cast lead projectiles. I have ben reloading for about 17 years or so. Just got into casting about 6 years ago. I am not sure what I enjoy more casting and loading or shooting. Collecting lead is getting hard to find at a reasonable price to. I like free mostly. Live in a big city so it is possible. At any rate I cast for 357 to 30-06. I Have ben working on K31 with a short throat that I need to do a cast on the chamber and throat. It is a hard one due to the very short throat. Love to shoot that gun any way.
- July 8, 2017 at 7:23 am #46146GhostHawkParticipant
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Well said, plain talk, clear instructions.
There are no shortcuts in precision shooting of cast.
If you try you end up out in the sticks bogged down with no clear idea of where the hard trail is.
The rifles that I have taken the time to chamber cast, make dummy rounds and work up right have always repaid that investment many times over.
So take the time, do it right the first time. Enjoy the journey.
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