Anyone load subsonic 300 Blackout?

[diavic]

I am having trouble with subsonic 220 grain 300 blackout short cycling.

I loaded them with 9 grains of lil gun. The rifle is a 16" AR with a Carbine gas system.

I tried the loads in an AR pistol and they cycle fine.

Does anyone have any recommendations, or maybe a better powder to use?

 

[lazarus0213]

I would believe its a problem with the carbine length gas system. You should be using a switch block or adjustable gas block on anything longer than a pistol length system. At least me expierance has shown the carbine always has issues with subs. Supers do not seem to have any issue up to the carbine, but iffy with a midlength

 

[gopurdue02]

I am using 220 grain Sierra with 10.2 grains of Accurate 1680. The is the only powder that I experimented with that A) Cycled the gun B) Hold the bolt open. That is with a 16 inch barrel.

 

[red_zr24x4]

IM SteveB, I've shot his and it cycles nicly and works in his can great.

 

[ZbornacSVT]

I loaded my 220s on top of 9.9gr of H110....only shot a few of them, but I thought they were a little hotter than they should be. Haven't loaded any more yet to play with.

 

[atalon]

I have heard of people having to use a lighter weight buffer spring or widen the gas hole on the gas black and/or the barrel. I would try the powder from above first though.

 

[hemicharger]

1680 is the preferred powder for subsonic 300 BLK loads. I get reliable extraction and will hold the bolt open on the last shot with 10.3 grns using a 220-225 gr bullet out of an 8.2" barrel w/ suppressor. Please try a different powder becore you go drilling open your gas ports.

 

[Steve B]

I don't put cartridges in my can. It would make it hard to sit down. I have a Noveske 8" with a Thompson Machine "Thirty". I'm using a carbine buffer, 10.8gr of A1680, 2.126 OAL behind a 220gr Sierra MK. Runs in my rifle flawlessly.