SBR AR15

[Niceguy]

Thinking about starting an AR pistol build that will eventually be an SBR. I figure it may be the only way I'll keep one...haha What is everyone's opinion on the best all around barrel length and twist ratio having it be a SBR in mind? The happy medium of light weight and compact yet still not killing velocity and under 100 yard accuracy with 55gr-62gr ammo. Any other build suggestions or things to watch out for or what NOT to do would be greatly appreciated also. I'm not 100% decided to do this, but about 95% sure I'm going to...

[Wyldman]

For 55-62gr bullets, you'll want to stick to 1:9 twist for best accuracy.

[JustShootIt]

10 in seems to be the happy medium and allows you to still use "standard" rails/handguards, gas tube etc......Anything below 10 seems to have cycling issues...Not that they can't be remedied...

I had a 7.5 in AR pistol and it was a blast.......but I did have to make a few adjustments to get it to function reliable. Shot rather well 100 yds or less. 10 in barrel could give a little better results in accuracy, but then again, an SBR isn't intended to be a tack driver....

If you want one as short as possible, go 7.5.......if you want a good inbetween length go 10.....Anything over 10 is waste of stamp IMO........

[dbh]

I am a fan of 1:7 twist. I have a 10.2" DD barrel with that twist on my SBR and it is very accurate !!

[Wyldman]

Wouldn't that be a bit too fast for 55gr bullets?

[Niceguy]

I was kinda figuring around 9-11" would about what I would be going for. Had no idea of the twist rate though. I would probably be using 55gr 95% of the time. Cheaper and easiest to find. Also have no plans of shooting over 100 yards.

[WLJ]

My two cents worth.
5.56 was designed around a 20" barrel and relies on velocity to fragment and otherwise do weird things in the human body. Going to 16" was bad enough but going to a 10" means you're dropping below the velocity needed for proper fragmentation, most studies I've seen suggest at least at a min 2700 fps and up is needed. At muzzle most 55gr rounds would be around 2600 fts with a 10" barrel, going heavier than 55gr would only drop that further. I would (IMHO) suggest 45gr bullets in a 10" 5.56 SBR to maintain some semblance (really barely) of proper vel and the less stable the better, in other words don't use too fast of a twist rate.

[Niceguy]

Also figured I would be using a Eotech, or red dot of some kind...

[justang1997]

I'd go 14.5. You are tax stamping the lower not the upper so if that don't suit your fancy just go shorter. No paperwork needed. I'd also go 1:7 twist. No reason to deviate from mil spec. Velocity plays a part in stabilization so shooting lower velocity .223 and not 5.56 added to the shorter barrel means more twist. I'd rather have a little more spin than just enough.

[dbh]

Go shooting with me and try mine out. IMO, paying $200 to go from 16" to 14.5 is a waste of money.

[Niceguy]

Thanks for all the advise. Thanks for the offer dbh, I'll definitely take you up on that soon.

[guncrank1]

10 inch 1-9 twist

[ssracer]

I am a fan of 1:7 twist. I have a 10.2" DD barrel with that twist on my SBR and it is very accurate !!

I think you mean 10.3"...I've got the same one..lol love it

[Niceguy]

I am a fan of 1:7 twist. I have a 10.2" DD barrel with that twist on my SBR and it is very accurate !!

I think you mean 10.3"...I've got the same one..lol love it

Wasn't yours keyholing or having some issue? What was the culprit of that? Just curious so I can avoid that issue. Any other what or what not to do advice anyone has I appreciate also...

[shelbygoat]

Buy it, register it, and keep it. Don't trade it

I think my next stamp will be an SBR, which will also include a supressor.

[Niceguy]

Buy it, register it, and keep it. Don't trade it

I think my next stamp will be an SBR, which will also include a supressor.

This is why I'm going SBR, so it won't come and go...haha

[ssracer]

I am a fan of 1:7 twist. I have a 10.2" DD barrel with that twist on my SBR and it is very accurate !!

I think you mean 10.3"...I've got the same one..lol love it

Wasn't yours keyholing or having some issue? What was the culprit of that? Just curious so I can avoid that issue. Any other what or what not to do advice anyone has I appreciate also...

That was my old 16" AR. Turned out to be an ammo issue. Something with that batch of wolf wouldn't stabilize the bullet out of the 16" barrel.

[ssracer]

Go shooting with me and try mine out. IMO, paying $200 to go from 16" to 14.5 is a waste of money.

I agree. Just put a 1.5" flash suppressor on it and save the $200

[Niceguy]

Cool, thanks for the info. Yeah, I agree also on the 14.5" or whatever. I thing ~10" is perfect. Long enough to have some rifle round effectiveness, yet not so short that I might as well just carry a pistol.

[shelbygoat]

my 7.5" is freaking short

[Niceguy]

my 7.5" is freaking short

That just seems to short to have much benefit of having an AR and it will probably be my only AR.

[dbh]

As Justang said, you can get different uppers. I recently got a Spikes .22 upper with a 5.5" barrel and 7" rail. With the suppressor on, it is shorter than my .223 upper and a blast to shoot !!

[Niceguy]

As Justang said, you can get different uppers. I recently got a Spikes .22 upper with a 5.5" barrel and 7" rail. With the suppressor on, it is shorter than my .223 upper and a blast to shoot !!

So you SBR the lower and then can use whatever you want on the upper?

[ssracer]

The lower has the serial number so it is the part that gets the tax stamp. You can swap multiple uppers onto it. I thought you couldn't go shorter than the length on the stamp though..could e wrong

[325MOUTguru]

This thread is useless without pictures....

10.5 FTMFW