7inch AR-15

mrnkc130 · July 30, 2009, 04:29 AM

I recently purchased a 7inch pistol at a gun show with the intention of making it an SBR (currently mulling thru the paperwork). Its a rock river a4 upper with a DPMS lower. everything stock and new except low pro gas block and CAR length quad rail. After i purchased it i ofcourse went looking thru the internet for ideas about what i wanted to do with it. I have noticed a lot of people complaining about any AR with less than 10.5 inch barrel not being reliable and prone to problems. does anyone have such a set up and had problems with it? anything i can do? also what can i hope for accuracy wise? I am anxious to start the break in on it but would appreciate any input on what i have gotten myself into with such a short barrel.

also on the form 1. I dont live in city limits...should i get county sheriff office to sign off? or will closest city (same as address on DL) be good?

thanks for the help!

jmorris · July 30, 2009, 09:43 AM

I have seen several 7” setups that run but they are pretty hard on suppressors. 10.5” is about as short as you want to go if you plan on adding a can.

flight954 · July 30, 2009, 09:53 AM

7" seems a little short for an 5.56 (.223) SBR. I would stick with 10"-14.5". Of course my 10" set up is a 9mm so there's no gas block, tube or key. I have 2 set ups for the 9mm, a 5" TROS 3lug suppressed(this runs flawlessly). Then I have a 10" Spikes barrel and I have a few cycle problems before the rifle warms up.
Then I have a registered RR pistol lower in 5.56(.223) w/ a POF gas piston 11.5" upper that has never given me one problem and it will eat anything I feed it. I'm waiting on my BATFE approval to SBR.

Bartholomew Roberts · July 30, 2009, 12:32 PM

Denton County Sheriff will work fine for the CLEO sign off.

jmorris · July 30, 2009, 02:12 PM

Ahh, I assumed you were talking about .223, you'll be fine at any length if you have a 9mm.

mrnkc130 · July 30, 2009, 07:58 PM

yeah sorry its a .223

here is how far i have gotten so far...

July 30, 2009, 04:29 AM	#1
mrnkc130 Senior Member Join Date: July 27, 2009 Location: Justin, TX Posts: 149	7inch AR-15 I recently purchased a 7inch pistol at a gun show with the intention of making it an SBR (currently mulling thru the paperwork). Its a rock river a4 upper with a DPMS lower. everything stock and new except low pro gas block and CAR length quad rail. After i purchased it i ofcourse went looking thru the internet for ideas about what i wanted to do with it. I have noticed a lot of people complaining about any AR with less than 10.5 inch barrel not being reliable and prone to problems. does anyone have such a set up and had problems with it? anything i can do? also what can i hope for accuracy wise? I am anxious to start the break in on it but would appreciate any input on what i have gotten myself into with such a short barrel. also on the form 1. I dont live in city limits...should i get county sheriff office to sign off? or will closest city (same as address on DL) be good? thanks for the help!

July 30, 2009, 09:43 AM	#2
jmorris Senior Member Join Date: November 22, 2006 Posts: 3,077	I have seen several 7” setups that run but they are pretty hard on suppressors. 10.5” is about as short as you want to go if you plan on adding a can.

July 30, 2009, 09:53 AM	#3
flight954 Senior Member Join Date: November 1, 2006 Location: Cypress, Texas Posts: 933	7" seems a little short for an 5.56 (.223) SBR. I would stick with 10"-14.5". Of course my 10" set up is a 9mm so there's no gas block, tube or key. I have 2 set ups for the 9mm, a 5" TROS 3lug suppressed(this runs flawlessly). Then I have a 10" Spikes barrel and I have a few cycle problems before the rifle warms up. Then I have a registered RR pistol lower in 5.56(.223) w/ a POF gas piston 11.5" upper that has never given me one problem and it will eat anything I feed it. I'm waiting on my BATFE approval to SBR.

July 30, 2009, 12:32 PM	#4
Bartholomew Roberts member Join Date: June 12, 2000 Location: Texas and Oklahoma area Posts: 8,462	Denton County Sheriff will work fine for the CLEO sign off.

July 30, 2009, 02:12 PM	#5
jmorris Senior Member Join Date: November 22, 2006 Posts: 3,077	Ahh, I assumed you were talking about .223, you'll be fine at any length if you have a 9mm.