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Thread: Two novice Gas Check Questions!

  1. #1

    Two novice Gas Check Questions!

    For you experienced guys, Im sorry about these two novice questions. My neighbor passed and his wife sold me a few hundred 125 & 130 Gr. 9-MM cast lead bullets. Also a hundred or so 154 Gr. - .308 cast lead bullets. I shoot both 9-MM and .308 regularly but have never used cast bullets maybe this experience will make me a believer.
    The 9-MM bullets do not have gas checks; instead they have a flat base and either a slender green or red ring encircling the bullet about 1/16th of an inch above the base. Question #1 Does this ring take the place of a gas check?
    The .308 bullets all have a flat base with a rebated edge. The stock included five bullets with a copper gas check installed on the rebated edge and something that looked like white putty in the bullet grooves. Question #2 do I need a special tool or die to install a gas check or can I just push or hammer it on; also what is the white putty lube?

  2. #2
    Boolit Master

    Join Date
    Apr 2014
    Way up in the Cascades
    Cast bullets can generally be fired very successfully without gas checks if the velocity is kept below a certain level. What that level is depends on the bullet. The green and red rings you see are probably bullet lube that was pressed into the lube grooves when the bullets were sized. The white putty is likely also lube, but a different kind. There are many kinds and formulas of bullet lube, as you will discover by reading some of the past threads. As for installing the gas checks on the bullets, used to be that Lyman made some that you just pressed on. I used to lie them flat on a table surface and put the base of the bullet into the gas check and push downward. Now days almost all are installed by the sizing/lube machine when the bullet is run through the machine for sizing. The machine also crimps them on, so if you can see a slight crimp at the top rim of the gas check, then they are of the latter type and were put on as described.

  3. #3
    Boolit Master Bazoo's Avatar
    Join Date
    Dec 2013
    Cecilia, Kentucky
    The thirty caliber bullets you describe have a gas check shank. It's generally advisable to use a GC when the bullet in question is made for one. Using a GC design without the GC is a little more advanced. At rifle velocities GCs are generally needed.

    The 9mm bullets are not made for GCs because they will see less pressure and velocity than a rifle bullet. GCs help the bullet grip the rifling better and give a better seal from the expanding gas in higher pressure loadings.

    The colored rings will be some variety of lube. It usually is some combination of wax and grease. Gas checks bullets still require lube. The lube under pressure not only lubricates the bullet to barrel interface but it also contributes to sealing the pressure of the expanding gas behind the bullet.

    Generally bullets will need to be sized to an appropriate diameter as they come from the mould a few thousands oversized. For example the 30 rifle bullets will likely be .310-.311 in diameter and you'll want to size them slightly to .309-.310, or even size them minimally to .311. Sizing them is swaging them, and makes them perfectly round and also crimps the gas check.

    A lubesizer tool such as Lyman's 4500 will size the bullets and put lube in the grooves at the same time. Lees push through sizing dies will only size the bullet. With lees tool you'll need to either pan lube or tumble lube the bullets. Pan lubing is where you set the bullets in a pan and pour melted lube around them so that when it solidifies it fills the grooves in the bullets. Tumble lubing is a liquid coating you squirt on the bullets and it coats them with a thin layer all over.

  4. #4
    Boolit Master

    Walks's Avatar
    Join Date
    Jun 2016
    Just to add more confusion.
    Getting the Gas Checks on straight is Extremly Important for accuracy.

    Lyman makes a gas check seater that fits on both their Lube-Sizer & the RCBS. And Saeco makes a built in one for their Lube-Sizer.

    These are used before sizing & lubing to ensure the gas checks are seated squarely.

    Buy a Lyman Cast Bullet Handbook #4. It will explain Casting & Loading Lead Alloy Bullets.

    Good Luck
    I HATE auto-correct

    Happiness is a Warm GUN & more ammo to shoot in it.

    My Experience and My Opinion, are just that, Mine.

  5. #5
    Thanks for all the good information -- it looks like I have a lot more learning ahead of me. Keep it coming if you think of something else important.

  6. #6
    Boolit Man Castaway's Avatar
    Join Date
    Dec 2005
    Dade City, Fl
    Another, and cheaper option to install gas checks is the Lee Sizing die.

  7. #7
    I'm A Honcho!

    DukeInFlorida's Avatar
    Join Date
    Oct 2009
    East and South of you
    Give this a good read, it should explain a lot for you:
    From Ingot To Target: A Cast Bullet Guide for Handgunners

    NRA Life Member
    NRA Certified Metallic Cartridge Reloading Instructor

    Author of a book on reloading
    ILSA MEMBER http://www.internationallawnsteelsho...ssociation.com

  8. #8
    Boolit Master
    Join Date
    Jul 2013
    barry s wales uk
    i use a lee sizing die too.works well

  9. #9
    Boolit Master

    leadhead's Avatar
    Join Date
    May 2006
    Leechburg Pa.
    Go back to your neighbor and see if she still has the lube sizer
    and see if she will sell it to you.

  10. #10
    Boolit Master slide's Avatar
    Join Date
    Jul 2011
    NOE sells a gas check seater. It is outstanding! It puts on the checks good and straight. Just another option.
    Boolits !!!!! Does that mean what I think it do? It do!

  11. #11
    Boolit Mold Shamus's Avatar
    Join Date
    Feb 2013
    I really like the NOE gas check seater, it solved my .50SR gas check issues. Makes getting them on straight much easier.

  12. #12
    Boolit Mold
    Join Date
    Oct 2013
    On my .429" bullets, to crimp / seat all of my gas checks on straight using my RCBS sizer, I found that I first had to run the bullet into the die upside down. (Gas Check up) Once all the gas checks were seated, the bullets were ran through again with the check down and the bullet then lubricated. A pain in the butt but it saved buying the NOE seater.

    Seating the bullets check down cost me around 10 % of the bullets. I still haven't figured out why.

    For you newbies: If there is any question of whether the gas check is crimped on straight, simply put the bullet in your caliper and hold it up to the light. That will tell you in a hurry if it is straight.


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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