I have a revolver that shoots 10MM boolits and I found that if I shoot plain base boolits faster than about 1200 fps, I get leading in the barrel. Another funny thing about revolvers is that if I shoot non-crimp grove boolits in them with cases that are not full of powder, I get setback in the boolits and so it gives pressures that are not what was anticipated.
So with 10mm in the revolver, I pick powders that will fill the case and most of these are slower magnum style powders. One exception is Trail Boss - that is really fun to shoot in the revolver.
Anyway, I generally use AA#9 and a full case of that powder pushes my 180 grain boolit in the 1350 fps range. So, PB boolits with this charge do lead my barrel. There's one way to fix this: GAS CHECKS!
I have a 40 caliber mold that makes a GC boolit and is a 180 grain it is the Accurate 40-180 BG. https://accuratemolds.com/bullet_det...ullet=40-180BG I had them make it without the lube grove since I PC / Hi-Tek my boolits.
There is a major flaw with this though. It is not particularly easy to find 40 caliber gas checks.
The solution here is to make my own.
I start with 28 ga dead soft copper sheets, and then I cut strips for punching out disks. I have also used aluminum flashing, but it must be non-tempered! A while back I got a pretty good deal on a bunch of 6"x12" copper sheets, so I am still using those.
My Die is a Pat Marlin die and the width needed to make 40 caliber GCs is 1.5 cm. So, I mark my copper sheets and start cutting strips.
I do check that I have the right sized strips before cutting a whole bunch of strips. I cut one and them make sure it fits properly in the die.
After I've cut all my strips, I setup my cutting die. Today I am making about 650 checks, so I used 3 sheets and each sheet has 20 strips. I get 11 disks per strip so ends up being 660 except that occasionally I only get 10 in a strip and I also occasionally drop and lose one... I'll find these some time later and not remember which size disk it was - but that is another story.
To setup this die, I screw the top into my press and then put the cutting die into the shell holder. Now this part is important. To align the cutting die I very carefully raise it up into the top part of the die watching very carefully to see if it is aligned. If the cutting edge touches any part of the top part of the die it must be rotated until it passes perfectly through the top without touching. Not doing this will damage the cutting edge! I also check the cutting die after each strip I punch disks out of because it will rotate and move while punching out disks...
One thing to note is that punching out disks from copper strips requires some force and will shake / rattle your work bench. This said, make sure loose items are moved / tied down / etc otherwise they will walk around your bench.
Once my die is setup, I start punching out disks.
When punching out disks, occasionally the strip will bend/twist/etc. I raise up my ram and gently touch the metal to bend it back if necessary.
After a while, I end up with a big pile of disks and it is time to start forming the disks into my actual gas checks. I raise the ram up into the top of the die and fix the cutting edge into the top with the included grub screw and then remove the grub screw for the forming part of the die. I also have a piece of aluminum that will push on the ejector rod to eject the formed gas check.
Then I start forming gas checks.
After a while, I've got a bunch of gas checks!
And I have my boolits and their future gas checks.
The next step is to install the gas checks. I do this by installing them and then resizing my boolits to hold them on. The barrel on my revolver slugs right under 0.400" so I resize to 0.401".
At the end of the day, I've got about 650 or so 180 grain 40 caliber gas checked boolits! These guys will be loaded to full power at about 1350 fps. These are accurate and do not lead my barrel.
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