300blk and SBR barrel size

jmike1487 · May 22, 2016

I looked and looked but couldnt find what info I was looking for so here is my post.

I'm thinking about doing 300 blkout and Sbring it as well. I've read that a 9inch barrel is pretty ideal for 300 blk suppressed due to all the powder burnt off quickly. But Maryland and all its glory has the OAL of 29". So would a 10.5 barrel be too much and not work properly? I have a SDN-6 can that I will be attaching to it as soon as it's out of NFA jail.

clandestine · May 22, 2016

10.5 will work just fine. You can use a 9.5 with a pinned and welded muzzle device too.

HordesOfKailas · May 22, 2016

I have a 10.5" 300BLK pistol build. Seems to work just fine. No issues with cycling or accuracy.

clandestine · May 22, 2016

Be sure the barrel you select has pistol gas, not carbine gas.

jmike1487 · May 22, 2016

clandestine said:
Be sure the barrel you select has pistol gas, not carbine gas.

Thanks.

Klunatic · May 22, 2016

I have an 8.5 and 10.5 both work equally well. About +100/fps out of the 10.5".

outrider58 · May 23, 2016

Jmike, be careful with your can selection. Some will not recommend going below 10''. I'm shooting a Rainier 10.5'' Ultramatch with a YHM Phantom 762 LTA. It is a tack driver(when I'm having a good day), but recommends not going below 10" barrel.

Hawkeye · May 23, 2016

jmike1487 said:
I looked and looked but couldnt find what info I was looking for so here is my post.

I'm thinking about doing 300 blkout and Sbring it as well. I've read that a 9inch barrel is pretty ideal for 300 blk suppressed due to all the powder burnt off quickly. But Maryland and all its glory has the OAL of 29". So would a 10.5 barrel be too much and not work properly? I have a SDN-6 can that I will be attaching to it as soon as it's out of NFA jail.

There have been a couple of other threads about this bouncing around here. Like Clandestine said, a 10.5" bbl will get you to 29" with just about any stock, easily. If you go shorter than that and pin and weld a muzzle device, same deal.

I wanted an 8.5" bbl (which is about the length that the round was developed for) but I didn't want to pin and weld a muzzle device. The only way that I found to get there was with a VLTOR A5 buffer tube (my tube is actually from BCM, but same deal) and a Magpul ACS-L stock with the 0.75" extended butt pad. This puts me right at 29" OAL without a muzzle device. Kind of annoying because I originally wanted to run a lighter stock, but it is what it is, and I have basically the rifle I wanted.

ducrider45 · May 26, 2016

I used a 10" barrel, standard tube and the Magpul extended butt pad on a CTR stock and I just made it. I shoot it with a Saker 762 on it with no issues.

300blk and SBR barrel size

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