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Thread: Deep Gas Checks For 357 SIG Cast Bullet

  1. #1
    Boolit Master
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    Deep Gas Checks For 357 SIG Cast Bullet

    I got a 357 SIG barrel for my SIG 40 S&W Auto.

    Have a mold coming for my Master Caster the mold is being made by Accurate and the bullet is the 35-120G.

    I made this bullet for a short fat 120 grain bullet suitable for the 357 SIG.

    The bullet was designed using SolidWorks.

    I generally powder coat and install gas checks on all of the cast lead bullets.

    The neck on the 357 SIG is short and I wanted a deep gas check for installation on the bullet.

    The deep gas check would keep the gas check of the neck of the case when the bullet is seated.

    I made a gas check maker and made some gas checks as a test.

    The gas checks were installed on a 125 grain cowboy action bullet to check the fit of the deep gas check.

    Gas checks were made from cola can material .004 thick and aluminum roof flashing .008 thick.

    The deep cup on the gas check results in a large diameter disc before the cup is formed on the gas check.

    There is a lot of metal at the top of the cup that is fold over into it self when forming the deep cup.

    The .008 thick roof flashing wants to tear while making the deep cup.

    The cola can material just kinds of wads up while the deep cup is formed.

    The cola can material made the best check and installs the best on the lead bullet.

    When the mold arrives and a few bullets are cast then a new test will be made using the cola can material.

    The 125 grain bullets had been coated with the HI-TECK coating previously.

    Just another deal to mess around with.
    Attached Thumbnails Attached Thumbnails NO 5.jpg   NO 2.jpg  

  2. #2
    In Remembrance

    DukeInFlorida's Avatar
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    I load a shoot 357 Sig in my P229. In fact, it's my carry gun. I have been casting and gas checking cast boolits for decades, and have not yet successfully been able to cast for 357 Sig. The short neck on the 357 Sig, as you point out is the primary issue. I'll share some of what I have tested with you, hoping to save you some time and trouble:

    • The real issue with the short neck of the 357 Sig is "bullet set back". Even with plated or jacketed bullets, simple recoil, and even placing rounds in and out of mags will cause the bullets to get pushed into the case a bit. Some of the manufacturers have taken to adding a slight amount of gel glue in that area to hold onto the bullet better.
    • I start with a very shallow bell mouth (you HAVE to bell mouth these rounds to get bullets straight, and keep the necks from getting bent), and install ONLY jacketed or plated bullets at this time (no success whatsoever with any cast experiments!)
    • I use a Lee factory Crimp Die and give the very top of the neck (after the bullet is installed in the case) a firm crimp. That really locks the bullet in place, and all pressure testing I have done with strong thumbs, mag fills and empties, and lots of measurements.... the bullets don't suffer from bullet setback.
    • HOWEVER, all attempts to do this with cast bullets failed for a few reasons..........
    • The gas check gets wiped off the base of the bullet when encountering the neck angle, no matter how well it was installed. I tried opening up the space between the gas check maker punch an die, so that I could use slightly thicker material, and get "deeper legs on the sides of the cups"... No good. I tried all sorts of material thickness and metals, .008" through .020" and aluminum, copper, and brass. No good.
    • Finally, the bullet setback issue is still there. Any and all attempts to use a Lee Factory Crimp Die on those cast boolits I tried caused the lead to deform in all the wrong places, and caused lots of erratic flights.

    I finally gave up the quest. Just not worth the issues. I've gone to using Berry's Plated, Extreme Bullets plated, and Montana Gold jacketed for my practice ammo, and Hornady XTP, all in 125 grain (which is the PERFECT bullet weight for 357 Sig!) for my carry ammo.

    Hope this helps you save some time, trouble, and effort. I have to guess that I put hundreds of hours, and I am pretty sure I am way ahead of most with some of this stuff. I wasn't just poking around in the dark for a solution. I shoot thousands of 357 Sigs a month, and wish I could come up with a cheaper way to shoot them.


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  3. #3
    Boolit Master
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    A lot of time was spent in making 3-D models of the case , the bullet and the gas check.
    With the deep gas check and the 35-120G bullet the gas check should be in the neck area when the bullet is seated.

    Hope it works so a cast lead bullet can be shot in the 357 Sig that is powder coated and has a deep gas check.

    The bullet is slick sided with on groves.

    May or may not work but will give it a try.

    Any comments are welcome.

  4. #4
    Boolit Master



    Springfield's Avatar
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    I loaded a lot of jacketed bullets in my 9mmAE, sort of a 357 SIG. It has an even shorter neck, and I had no problems with set-back. If I was to get back into loading 9mm ae/357 Sig with cast I would just use a crimp groove bullet and headspace on the shoulder, roll crimping the case mouth.

  5. #5
    Boolit Master
    Ausglock's Avatar
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    G'day Been loading HITEK coated lead in 357Sig for about 10 years.
    Glock 35 with a Lissner barrel.
    No Gas checks needed. I have pushed 105SWC to 1700 FPS with no leading.
    Also run 170gn RN up to 1400FPS with no leading.
    Hooroo.
    Regards, Trevor.
    Australia

  6. #6
    Boolit Master
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    I've been casting and shooting Saeco #924 that drops at 120 gr. out of lino. No setback, no loss of the check, excellent accuracy. Headspace off shoulder and crimp into the groove. Been doing this for 10+ years and never had any problems with it. It shoots well in 9MM and 357 mag also. Good all around Boolit with AA9. Rod

  7. #7
    Boolit Master
    xacex's Avatar
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    I shoot the Mihec 359-125 h/p in my conversion barrel and have no problem. No leading, but I am powder coating. This is the second gun I have tried it in, and have not experienced boolit set back, or any other issues out side of finding a powder that would give me good accuracy. I settled on blue dot, but it does not meter well in some equipment. I dont seems to have a problem, and it shoots just fine. Nothing like a 357 sig fireball out of a 3 inch barrel.

  8. #8
    Boolit Master
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    I believe that a mold that throws a bullet cut for the gas check, using a crimped copper gc, would work well even if the check is below the neck junction. Some of my most accurate loads have the GC well down into the case and the GC stays on.

  9. #9
    Boolit Master dkf's Avatar
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    I have been using a 147gr (actually 151gr) designed for the .357sig from Accurate. I epoxy paint coated a bunch and the neck tension was very good (sized .358"), accuracy was good. I had some that sized .3575" which I coated with too much Alox, they slip a lot easier with the bullet slipping some when I lightly crimped them. I got all the stuff to switch over to Hitek now I just need to get time to cast and coat a batch.

  10. #10
    Boolit Master
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    357 SIG With New Bullet

    Finally go some range time with the SIG P 239 with the 357 SIG barrel and the new bullet.

    The bullets are cast lead with the 92-6-2 alloy, powder coated and a .010 thick aluminum gas check was installed on the .357 sized bullets.

    The gas checks stayed on all of the time, none came off during the firing.

    Fired 70 rounds without any feed or ejection problems.

    The bullet is the Accurate 35-120G which I designed using SolidWorks.

    Gun still shoots low to the left at 25 yards but pistol function well with the bullet design.

    Need to find some adjustable rear sights for the SIG P239.
    Attached Thumbnails Attached Thumbnails 357 SIG  35-120G.jpg  

  11. #11
    Boolit Grand Master

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    I'm with Duke on this one. Played for practice and XTP for "real stuff"

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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