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Thread: Gas check makers

  1. #1
    Boolit Bub
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    Gas check makers

    Can anyone provide a link to blue prints to build your own gas check makers and dimensions of factory gas checks?

    I found a guide years ago but lost/deleted the download

  2. #2
    Boolit Buddy Sam Sackett's Avatar
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    Here is a posting with a few links. May be what you are looking for…..

    https://castboolits.gunloads.com/sho...as-check-maker

    Sam Sackett

  3. #3
    Boolit Master
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    There's a couple stickies at the top of the forum. One has some mechanical drawings by Idz, for a one stroke gas check maker. There's another sticky showing the standard shank sizes and appropriate disc sizes for many calibers. But I think it's missing the standard check thicknesses.

    For PB checks, you can kinda wing it, a bit, once you understand how the die works.

    Die body (part that goes in the ram like a shellholder): a tube that has an inner diameter the same size as the discs you want to cut. Slot in the side of the tube for inserting the material. Button in the bottom of the tube which is roughly the same diameter you want the ID of the gas check to end up. Top of the button should be just about level with the slot, so the material lays right over the button as it's getting punched.

    Punch (will screw in the top of the press): a tube that slides into the die with a good fit. The inner diameter has to be larger than the button by the thickness of the material x2, plus 2-3 thous extra clearance. Only want about 1/4" length of the mouth of the punch to be at this diameter before it opens up maybe at least 5-10 thous, so the checks don't bind in there. The checks just keep pushing up through the punch as you form them.

    You only want that 1/4" or so length on the mouth of the punch to be tight, so you can use a short stroke. If you need a long followthrough to push the checks past the tight spot, you will have a lot more force to punch them out. The closer you get the disc cutting to the top of ram travel, the more leverage you get in a reloading press.

    In reality, unless you have precision lathe and equipment, you don't need to carefully measure anything except the size of the disc you want to cut. Get that down first, for the bore of your die and OD of the punch. For the bore of the punch, what I did was just bore it through too small. Then counterbore all but the last maybe 1/3 of an inch, too big. Then open out that band at the mouth just until a sized bullet falls through, freely. And then sand generously and polish. That puts you right were you want, provided you're using the right thickness material for this caliber and bullet shank. Then make your button. If the checks tear, make the button a little smaller.

    If your checks are too tight, open out the ID of the punch a little, plus or minus make a larger button, too. If your checks are too big, then you done messed up. But they'll probably still crimp on.

    Not rocket science. Once you get it close, be more careful.

    Once it's working, you can shorten the end of the punch a bit, if necessary, to shorten the stroke length and get maximal leverage. Just make sure the slot in your die is close enough to the top of the ram (die is short enough), so you can reach TDC, if possible. Remember that a strip of flashing is going to be sticking out the slot, so it can't go beyond the top of the press. So you might want to measure that distance before you start, so you have something to shoot for.

    You can potentially use the same die body for multiple gas check sizes, if they're close. Just make a new punch and button.
    Last edited by gloob; 03-14-2023 at 06:23 PM.

  4. #4
    Boolit Grand Master

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    Here is a link to Ed Smith's gas check maker (the links posted on Cast Boolits no longer work):

    https://docs.google.com/file/d/0BxHh...Ha-gFBnK6I4ZQw

    and the IDZ gas check maker:
    https://castboolits.gunloads.com/sho...gas-checkmaker

    I have made two of the Ed Smith design and like them. I am using thick old gutter aluminum that gets drawn a bit deeper than thinner material so wanted a "mallet" version.

    The Idz gas check maker is press mounted only.

    Both are single stroke gas check makers.

    There are also simpler to make gas check makers where you punch the disk then form the check. Search is your friend.

    Longbow

  5. #5
    Boolit Buddy
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    Just a quick question about these check makers: can the depth/height of a check be made any height you want? They all seem to be very shallow, hardly enough to make the cup/ Since my rifle molds have the check shank .100" long, why not make a check that grabs more of this shank?

  6. #6
    Boolit Grand Master

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    If you look at the Hornady gas check chart you will see that the deepest is 0.084" and most run around 0.060" to 0.070" except for .22 and .25.

    Yes, you could change the disk size or material thickniess to get a deeper gas check but you'd have to figure it out and see if the rest of the dimensions given would produce the deeper gas check without wrinkles.

    As I said, I am using quite thick old aluminum gutter at about 0.020" thick. I find that it draws a deeper cup with my Ed Smith gas check maker than more typical 0.014" thick material. I am using the mallet version though, not my loading press. I suspect the loading press would have a problem cutting and forming material that thick.

    If you went to a larger diskit may draw evenly or may not. Deep cups are usually run through several dies to draw the wall thickness down and deepen the cup. I don't think a gas check is deep enough to require that but if too deep if may wrinkle during forming.

    Not sure if there is any disadvantage... or advantage to a deeper gas check but I have to guess that commercial gas check suppliers figred out that the short gas checks work so that is what they make.

    Also, some gas check shanks ar elong enough to leave a gap for lube so an extra lube groove.

    Longbow

  7. #7
    Boolit Master
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    That all makes sense. Another advantage of a short gas check (shank) is that a lot of people find the bullets are plenty accurate without the GC with PC or lower charge weight.

    I'm guessing the shank diameter would also have to be more exact and less forgiving with taller checks. But with the cost of copper, what works good enough and is easier to manufacture seem to be good enough reasons to make short checks.

    That begs the question, why copper, if aluminum works as good? I bet it doesn't. It just works very well, which is way better than no check.

  8. #8
    Boolit Buddy
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    I can see the issue of the taller the check, keeping the cut disc concentric while forming. You can measure commercially made checks now that aren't even. I suppose the check doesn't need to be high to do it's job.

  9. #9
    Boolit Master
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    Quote Originally Posted by PopcornSutton View Post
    You can measure commercially made checks now that aren't even.
    I guess these are Gator or Sage checks, maybe? My Hornady checks are very uniform and symmetrical. They also appear to have an intentional shape to aid in going over the shank but staying on the bullet after crimping. It seems to work, too. When I pull checked bullets, the Hornady often stay on. Or they come off at the case mouth, if I used a taper crimp. My own checks usually come off deeper in the case neck.

    My Hornady checks don't have a bur at the edge. The walls have two separate angles. So the check is sorta straight until halfway up, then they taper out larger at the mouth. When crimped, the centerline of the wall gets pushed in a little and seems to grab on the shank.

  10. #10
    Boolit Buddy
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    I am getting away from crimp on checks, whether they be Hornady or Gator checks. If I was loading for a pistol or a hunting rifle, I wouldn't worry at all. But I am striving for the most rifle accuracy I can get, and a GC can cause issues. 30 caliber Hornady checks are dished and it is hard to get that disc flattened out. Sage gators aren't as bad, but they still don't flatten completely. (perhaps they should be annealed so they conform better?) Plus, I have removed crimped on checks after crimped/sized, and they deform the base of the bullet to a degree. They grab so close to the bottom edge of the bullet, the lead deforms some. Regular checks don't show any dishing when sized on, they come out fairly flat. But they aren't as even in height as you may think.

    Without a flat, even and perfectly square to the bullet axis base, accuracy suffers.

  11. #11
    Boolit Buddy
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    I used the one posted by IDZ, and they were great. I had several sizes made at work. I even had a set made to make percussion caps.

  12. #12
    Boolit Grand Master WILCO's Avatar
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    It's been a while, but here's one that I made:


    https://castboolits.gunloads.com/sho...and-GC-Trimmer
    "Everyone has a plan, until they get punched in the face!" - Mike Tyson

    "Don't let my fears become yours." - Me, talking to my children

    That look on your face, when you shift into 6th gear, but it's not there.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check