Gas Checks Y/N in Subsonic 300 BLK

[ProdigalSun]

Do you need to gas check the 300 BLK when rubbing it subsonic? I will be powder coating.

[KenH]

Since I've not shot a 300BO sub or super for that matter (my barrel is to be delivered today), and nobody has yet commented, I'll say from my casting/shooting experience with other calibers, with <1,000 fps I would not think you'd need gas checks, even with a WW type alloy.

I'll be following this post to see other comments.

Ken H>

[gds]

You do not need one at the subsonic level.

Now there are those that do not recommend gas checks period for shooting thru a suppressor, subs or supers. the concern being that the gas check can fly off the back of the bullet and damage your can.

I have fired many supers with gas checks thru my suppressor and have never had an issue. however I have pretty much stopped that practice and powder coat all my cast projectiles and have not needed to use gas checks.

[ProdigalSun]

Thanks. I didn't think that a GC was necessary, especially with the powder coat.

Boy-oh-boy am I ever happy to be away from pan lubing.

[80hp]

No gas checks needed. Use a plain base bullet. A gas check bullet without the check may loose some accuracy.
M.

[ProdigalSun]

+1 You're right, flat base is more accurate for subs. I did order a gas checked mold however. The reason was, ease of powder coating. Long .30 caliber rounds are really wobbly and tip over spoiling the powder coat. I fixed this by attaching .308 shells to a piece of wire lath by a screw through the flash hole. Just stick the bullets in the cases, and coat them. They only go in up to the top edge of the GC, which holds the bullet firmly, provides a great electrical contact, and keeps any powder coat from getting on the part of the bullet covered by the GC. Then I'll stick the GC on the back of the round and then run it up through a LEE sizer die. The GC is swaged onto the round, and the finished gas checked and powder coated round comes out at the exact diameter you choose.

I use Accurate Molds, really top notch stuff. Get a brass one. http://www.accuratemolds.com/


http://www.accuratemolds.com/bullet_det ... 15E3-D.png

[destrux]

I had a similar powder coating jig but I've since started doing the airsoft BB dry coat method and I'm really happy with the uniformity of the coating and how fast it is to coat them.

[ProdigalSun]

What's your method?

[Dr.Phil]

FWIW,

Gas checks are not needed for subs.
Like others have said, bullets designed for GC that do not have them installed will suffer decreases in accuracy.
Others insist on using gas checks all the time and report better accuracy from a GC bullet than a plain base one.

Gas checks were designed to stop gas cutting of the bullet base when pressures / velocities cross a certain threshold. (usually around 1,500 fps)
If you are interested in reading more on gas checks and all things regarding cast projectiles, check out this free E-Book:
http://www.lasc.us/Fryxell_Book_textonly2.pdf
http://www.lasc.us/

Here is the chapter regarding Gas Checks: http://www.lasc.us/Fryxell_Book_Chapter_10_GCkorPB.htm

[ProdigalSun]

Thanks. LASC is an amazing site, I've spent many hours reading and referencing the materials over there.

BTW... I noticed the Accurate 1680 at 18 grains, which should be supersonic, pretty much fills the case. With the 163 gr GC cast bullet I'm runing for supers, the powder is almost touching the gas check, ...This is ok right? The charts did show it as a compressed load, but never having done this before, it makes me a little uneasy.