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When is a Gas Check Necessary?

Discussion in 'Reloading' started by wavetrain75, Jan 23, 2010.

  1. wavetrain75

    wavetrain75 Useless Member

    Jan 31, 2008
    In a handgun load like .357, 9mm or .45?
  2. GioaJack

    GioaJack Conifer Jack

    Apr 14, 2009
    Conifer, CO
    You won't need one with the .45's, don't even know if they make a mould for it, velocities don't get high enough. With .357 I used to use them on a Lyman mould 358156, (SWC) in anything I pushed over 1100 fps or so.

    Depending on your alloy you can probably push that velocity without one but they used to be cheaper than dirt, not so anymore. I still have a few partial boxes, (Lyman's) with price stickers of well under $10 per box of 1000. Don't load that heavy anymore so I haven't used any in years but it's nice to have 'em just in case.

    Still have an ARCO bin filled with gas-checked SWC.

    Never used any on 9mm... can't recall seeing a mould for a gas-checked bullet weight in 9 but I suppose someone makes one.


  3. I see more use in a rifle load then a pistol load. They would work well for cast bullets in the standard pistol calibers, less clean up and faster speeds possible. Generally if the load is over 1100fps it's used to reduce the amount of lead that is melted.
  4. DustyJacket

    DustyJacket Directiv 10-289

    Oct 16, 2008
    Missouri, East of KC
    Any cast round going over 1100 in the barrel.

    Or any time you don't want lead boiling off the base of the bullet.

    I never used them, though.
  5. dudel


    Dec 10, 2008
    Texas Hill Country
    You're right about the speed; however, lead doesn't boil off the base of a bullet. It's not in contact long enough. Gas cutting yes, boiling off no.
    The burning propellant will not melt the base of a lead bullet! There is simply too much physical mass to heat to the melting point of lead (about 600-700F) in the short time a bullet is exposed to the propellant gas to bring it to it's melting point! If you want proof, examine wads used in shotguns or black powder cartridge loads after firing. They may show slight darkening, but won't be consumed in flames either! If the burning powder won't melt the plastic or burn up the cardboard, why would it melt a bullet base? The answer is, it can't.
    Same with sabots. Don't see any sabots melted into the bore.

    In fact, if the purpose of the gas check was to protect the base, why can you can get gas checks with holes in them (they almost look like washers)? Gas checks keep gas from getting between the projectile and the bore which leads the gas cutting and poor accuracy (and yes, some leading). So, I guess in a sense you are protecting the base, the rim of the base. If the projectile exits the crown with one side of the base first, accuracy will suffer.

    Way back when Jack and I were throwing cast stones, Dean Grennel wrote about using zinc washers as gas checks on cast boolits. Of the perforated gas checks, the best known might be the Wilk gas check, which allows a cast boolit to be pushed to some amazing speeds. Check out the Wilk gas check.

    They aren't even applied to the base, so they can't protect the base; but they can keep gas from cutting the projectile.

    Other perforated gas checks.

    Last edited: Jan 24, 2010
  6. WiskyT

    WiskyT Malcontent

    Jun 12, 2002
    North Carolina
    I load cheap range scrap with a max load of 2400 in 357 mag and a plain base bullet. 1250fps in a 4" gun and no problems. Gas checks cost as much as jacketed bullets do these days which is a total scam.

    If you're getting leading in a pistol, use a slower powder, a harder bullet, a bigger bullet, or all of the above.

    I can get leading at 900fps with the same bullet as the 2400 load if I use Bullseye. Fast powders used above the range for "target" loads will give you leading. Use Bullseye, 231 etc for light loads. Use Unique, Universal etc for +P loads, and 2400, AA9 etc for magnum loads.

    My above post refers to using a plain base bullet. I am not talking about using a gas check bullet with out the gas check. That's a different story. I have read about good results and terrible results doing that and I have never tried it myself.
  7. DustyJacket

    DustyJacket Directiv 10-289

    Oct 16, 2008
    Missouri, East of KC
    I stand (sit) corrected.