300 BLK-180gr CB - AA7- subsonic - Load ideas needed????

[gclark94560]

HI! New member but far from a new shooter or caster. Been loading 45 years and ex military competitive shooter. I'm also a founding member of WeaponsGuild.com and an 07FFL. www.gunbuilds.com is my other home. :-)

New to suppressors and to the 300BLK. I built an integral suppressed AR with 16" barrel ported back to 11 inch effective length. The porting is to form a reflex chamber for the first stage of suppression.

No gas system at all for maximum quiet so think bolt action with short barrel.

I made a barrel with a 1:10 twist. Bad choice perhaps but it's a superb Green Mountain barrel and was cheap.

Due to the Swinestein/Obama issue and there being zero powders for sale right now, I'm interested in trying AA-7 I have, with a 180 CB at subsonic speed. I'm looking for QUIET!

Anyone up to the challenge of helping me work out this bugger?? :-P

[Jupiter7]

What other powders ya got? If cycling isn't part of the equation, the world is your oyster. My 245gr cb load for rem700 is 5.5grs unique. I haven't seen data for aa7 but have for AA9. Hopefully someone else chimes in.

[gclark94560]

In what looks like a useable range - I have
H110
296 (about same as H-110)
HS-7 & HS-6
AA-7 & AA-5
Unique

Anyone know where to start?? :coffee:

[Jupiter7]

H110 and w296 make for loud subs. I shot some made up to cycle and function a 10", 8.5gr, 8.7, 8.9 and 9.1grs of h110, none functioned but no squibs either. Louder than a warm 45auto but no supersonic crack, no chrono but I bet I was right on the edge. I built my unique load around older 300whisper data, found in an American rifleman article, "loading the 300whisper". Out of a 16" barrel, it's quiet enough and subsonic. I use a 245gr accurate design.

[gclark94560]

Would 7 grains of Unique and a 180 gr bullet be a reasonable starting point in your opinion?

[Jupiter7]

I'd start lower. Maybe 6.0. I work subs down instead of up. Without a chrono, it's all a guess except for lack of a supersonic crack. Unique is good as it isn't position sensitive. Time of year(temperature, weather conditions) can also change subs to supers. I don't own a .30 cal suppressor so my work with them has been purely for experiment. In all theory, my eventual goal would be to push a 245gr lead boolit at a decent enough velocity to perform as a satisfactory hunting round. I've seen a picture of a deer killed with similar results, at 850fps. Something intrigues me about hunting with a lower sound, heavy bullet in a 10" AR pistol.

[gclark94560]

Jupiter7 - thanks so much. I'm going to go out and load 1 or 2 and see what happens! :-)

[gclark94560]

Jupiter7 - thanks so much. I'm going to go out and load 1 or 2 and see what happens! :-)

[gclark94560]

OOPS! Double post :-?

Anyway - tried one round with about 5.6 grains of Unique. I didn't have the #12 rotor for my Little Dandy powder measure. That would have been something like 6.1 grains.

Clearly not supersonic. Clearly quieter than the H-110 load. But not quiet. :?

I now need to look at my suppressor design and see what I can upgrade there.

Will keep you posted.

[Jupiter7]

Glad I could help. 300aac is a fun cartridge and cheap to shoot. Looking forward to your update.

[gclark94560]

Today's shot was with a Hornaday j-bullet @ 180 gr. I have 3 Lee molds on order (back order) from Midway. All in the 170 to 190 range. When I get them, I'll go nuts.

[Pirate69]

This may be of some help. Helping a friend get into the reloading and casting fun. Loaded some 9.5 grain H-110 behind the Lee 300 Blackout Mold (230 grains) and they all cycled the action without any problems. Accuracy was reported to be good with a fairly quiet load. Just getting started since we are having problems finding the "best" powder and primers for the 1,100 cases I just made from 223 stock. Don't think I will ofter that favor again.

[gclark94560]

"for the 1,100 cases I just made from 223 stock."

WOW! Great favor! :):):)

[gclark94560]

I am on hold with this for a short while. I'm waiting on a chrono I ordered from Amazon. It's a "Shooting Chrony 7000020 Alpha Chronograph, Red " according to Amazon.

When it gets here I can do some more meaningful testing.

:p :p

[Jailer]

Since functioning isn't an issue why not go with a fast pistol powder? A fast pistol powder will be burnt by the time the bullet exits the barrel and produce very little flash and noise.

I recently loaded up some of the Lee 312-155-2R tumble lubed with no gas check with 4.8gr of W231. They are a very accurate and run a consistent 1080 FPS.