.308 Sub-Sonic Questions.

[az_paul]

I'm thinking about trying some .308 sub-sonic loads for use with a Gemtech HVT Suppressor. Have any of you gents given it a try? Any comments or load data sincerely appreciated. Thanks.

[O.S.O.K.]

The easiest and often best sub-sonic loads are made with handgun propellants. You might try 8 grains of IMR Trail Boss with 150 grain bullets and see what that gives in terms of velocity and then go up from there. Trail Boss is very light and fluffy and fills the case much better than any other powder that I know of. Beware of bullets failing to exit the bore! When you are testing to begin with, be damned sure that the bullet exits each shot. You are obviously looking for around 1100 fps. 10 grains gives 1175 and only 28700 psi.

Here's the IMR Trail Boss reduced load page: http://www.imrpowder.com/PDF/Trail-Boss-data.pdf

[az_paul]

WOW! Thanks, OSOK! That's what I needed to know. And, thanks for the link. The HVT is being used with the M1A. I'd like to shoot more and keep the noise down a bit. We live in the open high desert and the noise carries for miles.

[groovy mike]

use your own judgement and consult reloading manuals etc. but 10 grains of Red Dot is worth considering.

[L1A1Rocker]

The old stand by for 308 sub sonic is Red Dot. That being said, Trail Boss has earned a large following as well as 5744 (this is what I use). You may also consider drilling out the flash hole and using magnum primers. Trial and error is best for your particular application. Also, Lapua makes a 200 gr sub sonic bullet that will stabilize in 1:10 barrel (IIRC they claim it will also stabilaze in 1"12 barrels also but I do not have experance with that).

Good luck.

You may also consider the 247 "Bison" bullet:
http://www.gunsnet.net/showthread.php?14531-Hollow-Point-Cast-Bullets-for-Sale

[az_paul]

Again, thanks to you fine gents for the information! I'll post the results. Should be a fun experiment.

OSOK.....I will heed your advice and make sure every bullet exits!

[Helen Keller]

read up on trail boss loads as well.

[old Grump]

You really want to read this article before you go to far. I had thought about doing the same thing, not for a suppressor but just for target shooting. A lot of what I thought I knew was wrong.


Safely Develop and Load Subsonic Ammunition



http://members.shaw.ca/cronhelm/DevelopSubsonic.html

[az_paul]

Old Grump................I can't thank you enough for posting this article. Like you said, it's a real learning experience!

Think I'll just load some lower velocity rounds to get my feet wet, before trying the subsonics.

Thanks, again!