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Thread: How to size a gas check on a cast bullet

  1. #1

    How to size a gas check on a cast bullet

    Hey guys and girls. I am semi new to reloading. I have been loading for about 3 years now. But as of recently I have gotten into casting my own bullets. 9mm, .223, and 38 spl. I just got my first .223 lee mold and I have kind of a two part question. First being if I powder coat my rounds do I even need a gas check because i coat my 9mm and 38's? and second if I do need to or if I decide not to coat them how do I size it with the gas check? As in do I run them through my lee sizing die upside down or right side up?

    Any advise would be greatfully appreciated. Thanks everyone!

  2. #2
    Boolit Master Bazoo's Avatar
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    You dont have to use a gas check with regular lube if the velocity is kept modest. I dont PC, but im told you can forego gas checks with higher velocities with it. No matter whether you GC or not, you size them nose first with a lee push through sizer. That is the nose going into the sizing die first. The GC is not pressed against the bullet base to keep it on, but rather squeezed on the side wall, crimping it in place.
    Last edited by Bazoo; 05-10-2018 at 11:43 PM.

  3. #3
    Boolit Master

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    It won't hurt to try a few rounds without a gas check , but I wouldn't load up very many before testing them .

  4. #4
    Boolit Master
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    With correctly dimensioned gas checks the sizing die will crimp them when you size and lube.

  5. #5
    First thank you all for the info so far. The reason that I am asking this is because. My mold is .224 and my GC is 22cal but when I run it throw my SD nose first with the GC it does size the GC with the projectile but it also makes the GC longer if that makes any sense. Am I doing something wrong here?

  6. #6
    Boolit Master

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    Hmmm - I don't think that the gas checks should get longer , or at least not noticeable longer .

  7. #7
    By getting longer I mean that the dye stretched it lol

  8. #8
    I am sorry. I could not remember the word for what I was trying to say. Lol. What I ment was it is swedging the GC and basically forming a cup on the bottom side of the GC does anyone know what I am talking about?

  9. #9
    Boolit Master Bazoo's Avatar
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    The die will swage the gas check just like it will the bullet. Normally they come out flat on the bottom however, but if its just slightly cupped, its probably normal. They can be noticeably different in size. By that, I mean, If you hold a non sized check against the sized one, you'll be able to see a little difference, not 1/16 inch.

  10. #10
    Ok cool. Thank you very much

  11. #11
    Boolit Master
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    Quote Originally Posted by fishbait86 View Post
    Ok cool. Thank you very much
    What gas checks are you using? I have had problems installing aluminum gas checks on the Lee 55gr .224 cast bullets. I even attempted to install them bottom side first.

    What I have found what works the best with aluminum checks on these bullets is to use case sizing lube on a nylon case brush and lube the push through die. My bullets are already powder coated when I install the checks.

    Some people including myself have sized plain un-lubed cast bullets with very good results with push through dies. Sometimes I do this pre powder coat for specific reasons (in a clean die). However the gas checks seem to need the lube to keep from deforming.

    To answer your other question:
    I have not found a reason to gas check any powder coated bullet other than accuracy. The inaccuracy I am speaking of has nothing to do with bullet failure just simply the gas check designed bullet does not shoot well without the check on it. This is not true for all bullets and even seems not be true for all guns.

    My two experiences with this is the Lee 22 cal. bullet and the Lee 30cal. 160gr 2R TL. The 160gr shoots fine sub sonic but super sonic the groups go from 5 inches at 25 yards to one ragged hole at 25 yards.

    My experience with the 22 cal. so far has been 4" groups at 50 yards with the check to you can't keep them on a 3 foot square target backing without the check. This is at @2000fps. Some folks have done better both checked and not. Some folks have done a lot better using Hornady copper gas checks on the 22 cal.

    That's the fun part about shooting cast. All the experimentation.

    Motor

  12. #12
    Boolit Master
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    Quote Originally Posted by fishbait86 View Post
    I am sorry. I could not remember the word for what I was trying to say. Lol. What I ment was it is swedging the GC and basically forming a cup on the bottom side of the GC does anyone know what I am talking about?
    I think I know what you are talking about. If it is a Lee type push through die and you are sizing a lot the ram that pushes the bullet through the die may be a little under sized for the bullet/die combination. On several I had to turn a slightly larger ram to tighten up the tolerance between ram and inside of die to eliminate the problem. a couple of pictures showing the "cups" would help determine the cause and how bad it will affect accuracy.

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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