.300Blackout Shorty's.

Dr.K

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To the people that own one or know people that have one, Do you have it feeding reliably with subsonic ammo? I don't know much about AR's but on manufacturer websites it mentions that short barrel'd blackouts are unreliable when not silenced. Is this true? Im at a pistol only indoor range where I can't shoot .223. .300 blackout in subsonic form is insanely slow which means I could own an AR and actually be able to shoot it at my club! Any suggestions on a .300 blackout shorty? Should I build or buy? Any comments would be helpful.
 
The gas port size spec'd by AAC is meant to run 110-125gr supersonic from a pistol length has tube without producing excessive BCG velocity. Thus that gas system combination can produce problems with unsuppresed subsonic operation.

If you want to run subsonics without a suppressor there are a couple of options. Open up the gas port a bit or run a different (slower) powder that will produce a longer pressure dwell on the gas system. A large diameter muzzle device like the Noveski KX3 can also help to increase the dwell time.

Not sure how short you want to go but I run a 7" BLK AR and mine works just fine.
 
Kevin,

I am using the H110 and is working for me with 130gr bullet and 16" barrel. What powder do you recommend for a 10.5"?
 
1680 will work with the Barnes 180gr T-TSX in a 9" gun.
Also works with 180gr cheap SoftPoint.

Only load data I have is for 9" guns with subsonic.
 
I'm running a 9.5" AAC built upper on a Knights lower and it cycles all the ammo I've tried reliably. Both super and sub-sonic. From 110gr to 220.
I've loaded mostly H110 and used factory Remington Subsonic. No gas port changes should be required. At least on the AAC.
They do state on their website that the whole point of their uppers is to be able to run super or sub-sonic suppressed or un-supressed without any changes to gas setting or any other adaptation. Of course I have only been able to run it unsuppressed. :)
 
I am running an 8" with sub-sonics, no problems. I built it myself, so I opened up the gas hole slightly and use an adjustable gas block to tone it down for non-sub ammo. Might not be the prefered option, but if your gun runs subs without issue it is probably overgassed when running anything else.
 
Im at a pistol only indoor range where I can't shoot .223. .300 blackout in subsonic form is insanely slow which means I could own an AR and actually be able to shoot it at my club!

Careful with that idea, ask first before you do anything. My club, The Orillia Gun Club does not allow me to fire off my 9 mm AR because they claim that because the 9 mm is fired out of a rifle platform it gains super powers and will damage the backstops. I asked how so and for them to explain that, they quickly claimed the CFO says so. I brought up the issue of the S&W 460 and 500's and they quickly walked away without responding. Thanx "Denis" for your ballistics's knowledge.
 
I think I can trust AAC to have designed their uppers correctly.


I am running an 8" with sub-sonics, no problems. I built it myself, so I opened up the gas hole slightly and use an adjustable gas block to tone it down for non-sub ammo. Might not be the prefered option, but if your gun runs subs without issue it is probably overgassed when running anything else.
 
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