8" vs 12" barrel for a dedicated subonic and suppressed 300 Blackout. Teach me

[Tyler Kemp]

My buddy and I are planning an SBR AR build in 300 Blackout. Planning on always using subsonic with this upper, because there are plenty of other guns if more power is needed. I think 300 yards maximum should be doable, perhaps 200 on deer. Short and light was the thought process behind the gun so I was thinking 8" barrel, but Seekins recommended 12" as they said it would be more accurate. I'm not as familiar with ARs as bolt guns, where barrel length and accuracy aren't necessarily related, but wasn't sure if this was a different case in ARs.

Here was what I thought would make a great quiet and handy short range deer gun:

Seekins 8" upper: $1300 around 4lbs with suppressor adapter
Mag Tactical magnesium lower: $120 6oz
Palmetto State Armory lower kit with Geissele trigger: $220 11oz
ACE ultralight stock+folding stock adapter: $80+$80 5oz, maybe 1lb with buffer and spring and adapter:
Bushnell SMRS 1-6.5x scope: $1100 18oz
Aero Precision ultralight scope mount: $90, 3oz
-------------------------------
$2990 7.3lbs


Thanks for any help!

 

[jasonfaz]

Im surprised seekins would tell you that. No difference in accuracy, maybe slight variances in trajectory, but even then the differences will be minimal with subs. I went 8" for mine - which is also a dedicated suppressed rig shooting subs exclusively. The only way id go 12" is if you wanted to try and make a carbine gas system cycle subs rather than use a pistol length gassed 8"er.

 

[Tyler Kemp]

What accuracy are you achieving? I think 1moa should be achievable when it's not windy.

 

[rjacobs]

go as short as you can. subsonic is subsonic is subsonic. You are going to load to your barrel length anyway. Shorter barrel, in theory, can be MORE accurate than longer barrels due to their stiffness, especially with a can hanging off the end.

With a bullet like the 194g Lehigh expander, with a 100 yard zero you are looking at 32" of drop at 300 yards. JBM says at 300 yards it will still be moving at 950FPS which is in the envelope for expansion(I think they expand to 700fps)

 

[RTH1800]

Tyler,
When did Missouri legalize the use of suppressors on game?

RTH

 

[rjacobs]

Tyler,
When did Missouri legalize the use of suppressors on game?

RTH

A few years ago, not sure when. I think it was 2011 or 2012 when they made a bunch of changes to the state NFA laws saying "as long as it complies with federal law, you are good".

ETA: it actually looks like when silencers were legalized in 2010 for private ownership they then also became legal to hunt with because there has never been a prohibition in MDC law against it. All of the answers(responses from MDC agents) I have been seeing say "if its legal for you to own it, its legal to hunt with it".

 

[RTH1800]

Thanks. I think you better get it in writing. I checked due to wanting to hunt squirrels with my suppressed .22 RF. It is prohibited is the final answer up to last year. One mad WCO and you are in very great peril. Please be careful and again, suggest you find someone to put it in writing.
Good luck and have fun.

 

[rjacobs]

Thanks. I think you better get it in writing. I checked due to wanting to hunt squirrels with my suppressed .22 RF. It is prohibited is the final answer up to last year. One mad WCO and you are in very great peril. Please be careful and again, suggest you find someone to put it in writing.
Good luck and have fun.

Its in writing by several sources, but that is probably like an ATF letter it only pertains to that person. Its NOT prohibited by MDC law, therefor its legal.

Do a quick google search and a ton of websites will pop up with references(including a few by MDC representatives, or at least they are playing them on the forums).

The only regulation is no full auto and there are some caliber limits.

I have buddies that regularly hunt in Missouri with suppressors. I am not a hunter, but if I was it would be with either a suppressed 300blk AR or suppressed 300blk Rem700.

 

[jasonfaz]

Accuracy is fantastic. Especially with the above mentioned Lehigh 194 MEs. I dont necessarily consider it a 300 yard gun with the way I set up mine. I purpose built it as a short range rig. I highly doubt i would ever stretch it beyond 150. You could certainly shoot out to 300 as long as youre good adjusting for around 110 inches of drop at that range. More importantly however, a 100 yard zero sucks on that particular set up. Shooting 194 MEs at 990 fps with a 100 yd zero (which i naturally sighted in at from the start) I was apprx 2" high at 25 yds, f'ing 5" high at 50 yds, 3 inches high at 75 before arriving at my zero and adjusting to a consistent drop from there on. Considering i shoot 60%-70% inside 100 yds with this particular gun, the multiple holds under my 100 yard zero was ridiculous and made it pretty tough to put a round right where you want it to go unless you had a year to process what are IMO pretty non-traditional variations in trajectory compared to any supersonic round. I switched to a 50 yard zero and dont see any more than a half inch of variance throughout the 0-50 yard ranges before hitting my zero. MUCH better set up for me. The elevation drop from there to about 200 is easy. I hit 132" at 300.

 

[Birddog6424]

^^^ love the shooter.

Kryptek Highlander?

 

[rgrmike]

My buddy and I are planning an SBR AR build in 300 Blackout. Planning on always using subsonic with this upper, because there are plenty of other guns if more power is needed. I think 300 yards maximum should be doable, perhaps 200 on deer. Short and light was the thought process behind the gun so I was thinking 8" barrel, but Seekins recommended 12" as they said it would be more accurate. I'm not as familiar with ARs as bolt guns, where barrel length and accuracy aren't necessarily related, but wasn't sure if this was a different case in ARs.

Here was what I thought would make a great quiet and handy short range deer gun:

Seekins 8" upper: $1300 around 4lbs with suppressor adapter
Mag Tactical magnesium lower: $120 6oz
Palmetto State Armory lower kit with Geissele trigger: $220 11oz
ACE ultralight stock+folding stock adapter: $80+$80 5oz, maybe 1lb with buffer and spring and adapter:
Bushnell SMRS 1-6.5x scope: $1100 18oz
Aero Precision ultralight scope mount: $90, 3oz
-------------------------------
$2990 7.3lbs


Thanks for any help!

Tyler,
What have you heard about those Mag lowers? I just checked them out and it appears they're $179 on their site and $75 for blemished lowers. If they're as strong as aluminum lowers they seem like a winner to me. Might be my next build.

 

[jasonfaz]

^^^ love the shooter.

Kryptek Highlander?

Thks brother. It was my take on the Kryptek pattern, I just used colors that i thought matched my environment a little better than classic highlander. Thought it was a little to heavy on the FDE. It was the first go with the Kryptek pattern and Cerakote, turned out pretty good...

 

[secondofangle]

How much more velocity will you get with a 12" barrel over an 8"? Will 8" get you to the top of the subsonic velocity limit?

 

[redirt78]

I'm building something similar that will be for NV hunting, hogs and coyotes and short range deer out of some of my bow stand setups. I have the barrel and lower, Noveske 10.5" SS and my Mag Tac lower is waiting at my buddies place. Probably going with a short KMR from BCM. Wouldn't mind having the Seekins MCSR upper/rail either.

 

[rjacobs]

How much more velocity will you get with a 12" barrel over an 8"? Will 8" get you to the top of the subsonic velocity limit?

For supers I would guess 100-150fps faster in the 12" vs. 8" barrel. For subs, absolutely no difference when hand loading. Factory ammo, YMMV.

 

[strutter505]

anybody have any hand loads that they recommend/have tried for a 300 blackout subsonic?

 

[Glen Seekins]

Sorry, they must have been confused! In 223, we found 12" to be very accurate and 8" can cause baffle strikes (some 223 bullets don't stabilize)

In blackout.... Go as short as possible. Factory subs work awesome in our 8" barrel and shoot very well. Everyone has been every happy with it so far. I would recommend adjustable gas block. Cans from different manufactures differ in how much pressure they create. Tune it, lock it down and go!

 

[ptaylor]

Tyler,
What have you heard about those Mag lowers? I just checked them out and it appears they're $179 on their site and $75 for blemished lowers. If they're as strong as aluminum lowers they seem like a winner to me. Might be my next build.

100% satisfied with my MAG lower for $80 its a great light weight option.

 

[rgrmike]

Thanks Taylor. Seems like a winner to me. Are you running a stock AAC 9" upper?

 

[rgrmike]

ptaylor,
What's up with the pins in the lowe (looks elevated )? Can you run KNS pins in those? I had a trigger retaining pin break on me and have switched to all KNS pins…don't know if it's worth it but it really pissed me off when my factory pin broke.

 

[ptaylor]

Thanks Taylor. Seems like a winner to me. Are you running a stock AAC 9" upper?

Stock AAC 9"

ptaylor,
What's up with the pins in the lowe (looks elevated )? Can you run KNS pins in those? I had a trigger retaining pin break on me and have switched to all KNS pins…don't know if it's worth it but it really pissed me off when my factory pin broke.

They send extra long pins with the upper. Over 700rnds though this build and no issues so far.