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problems 300 blackout

CANNONMAN

CANNONMAN
Full Member
Minuteman
Apr 13, 2012
63
0
Utah
Has anyone had any problems or heard of any problems of stabilizing a 300 blackout rnd super or subsonic with a short barrel? What is the shortest you would go with? i'm going to convert an ar i have now into 300 blkout and trying to decide on a barrel length. planning on around 9.5-10.5" as of now. but also will want to shoot it through a 30 cal suppressor. IDEAS?
 
Re: problems 300 blackout

You're asking this one just a bit too early! Just built a 16" 300 Blackout but haven't had the chance to do any work with it yet. I went with a 1x8" twist, and am expecting it to run everything up to and including the 220s. I am about to start building a 10" version, also with a 1x8" twist. Anxious to start working with these, but still waiting on the paperwork for my suppressor to clear the feds.

More than happy to share any results or data with you just as soon as this particular ball gets rolling.
 
Re: problems 300 blackout

I have seen 8" rigs shoot well, 10.5" won't be a problem. The BO does well in SBR applications. Every gun will have a particular load it likes, you will have to try a few different ones out to see. The 110gr Barnes blacktip is the best supers while 220gr loads will be best for subs.

The BO will work with any .30 cal can as the blast is not near .308 type levels. There are BO specific cans out but I'd go for one rated .308/.300WM so I could use it on more powerful calibers if needed.
 
Re: problems 300 blackout

Well glen , I think I'm going to use my gen 1 Hide lower for a 300blk. here's the plan :
short barrel with the can in the rail . iv've read so much crap I'm going blind .

Give me a build plan ! 10" long barrel??

Greg
 
Re: problems 300 blackout

I'd suggest a 7 twist as minimum if you want to run 220s subsonic.
 
Re: problems 300 blackout

You wont have a problem. I think it's more the twist rate than Bbl length that you need worry about. Try to get a 7 if you can but an 8 will do. I have a 8" Bbl in a 7 twist and stability is no concern. What is a concern with shorter Bbls is getting enough MV worked up to achieve reliable cycling. Shorter the Bbl means you'll want a faster powder, so look towards something like H110 over AA1680.
 
Re: problems 300 blackout

Yeah kevin you'll have to keep us updated on your new build and i'll be right behind ya. Thanks guys for all the input.
 
Re: problems 300 blackout

i run a 10" 8 twist wiht a pistol length gas system and run 220 grn. smk over 11 grns of 1680 and it shoots like a dream. it sounds the same with my gemtech sandtorm as it does with my swr trident 9 suppressor. and it seems pretty stable as it will ring a 10 inch plate at 300yds everytime.
 
Re: problems 300 blackout

I have both 16" and 12.5" inch barreled uppers. I have run them both unsuppressed with supers and subs no problem. I finally got my suppressor last month and they both shoot excellent with the suppressor.

I love the 300 blk round anyone looking to build one will not be disappointed.
 
Re: problems 300 blackout

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: EWOAF</div><div class="ubbcode-body">You wont have a problem. I think it's more the twist rate than Bbl length that you need worry about. Try to get a 7 if you can but an 8 will do. I have a 8" Bbl in a 7 twist and stability is no concern. What is a concern with shorter Bbls is getting enough MV worked up to achieve reliable cycling. Shorter the Bbl means you'll want a faster powder, so look towards something like H110 over AA1680. </div></div>

Powder choice for any given cartridge is a function of bullet weight and gas system, but pretty much never barrel length.

H110 is not compatible with 300 BLK in subsonic for most ARs. For subsonic, use A1680, A5744, H4198, or RE-7.

For supersonic use H110/W296 nearly always and you can use A1680 for 150 and above.