Looks like I built a AR 9 now......

Preparedness Depot in Acworth, GA

boss_hawg

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Jul 13, 2015
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So when building the ar 9 what is a good barrel length?

Is there any major differences between a pistol and rifle length upper?
if suppressed, the general thinking is that barrels less than 9 or 10" will keep 147gr ammo subsonic. there is some variability to this. my 7.5 keeps 147s at subsonic velocities.

I'm sure there's a lower limit but I've seen 4" that work when suppressed (and maybe even not suppressed)

other than that, gotta watch out for atf regs. if you are using a pistol lower or sbr, then not a problem.

also, keep in mind the clearance necessary under a hand rail or free float that you'll need with a can if you go this route.
 
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PewPewPewCo

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Mar 23, 2015
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if suppressed, the general thinking is that barrels less than 9 or 10" will keep 147gr ammo subsonic. there is some variability to this. my 7.5 keeps 147s at subsonic velocities.

I'm sure there's a lower limit but I've seen 4" that work when suppressed (and maybe even not suppressed)

other than that, gotta watch out for atf regs. if you are using a pistol lower or sbr, then not a problem.

also, keep in mind the clearance necessary under a hand rail or free float that you'll need with a can if you go this route.
All lengths should keep 147 subsonic unless Yosemite sam was working the powder that day.

The barrel length has nothing to do with the reliability, it's direct blowback. Generally the less barrel there is the less likely you are to experience port pop. I used 5" on mine.
 

Cudruln

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Do you plan to suppress it?
I currently do not have any suppressed items. It is something I am looking at doing in the future. So to answer the question it is possible that it could be suppressed at some point in its life.
 

Cudruln

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I would like to go the pistol route (sbr in the future). So what would be a good barrel length that can work with or without the use of a suppressor? Do I need to be looking for a 7" or would the psa 10.5" kit work?
 

PewPewPewCo

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Mar 23, 2015
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I would like to go the pistol route (sbr in the future). So what would be a good barrel length that can work with or without the use of a suppressor? Do I need to be looking for a 7" or would the psa 10.5" kit work?
They'll all work but less barrel means less time with pressure in the barrel that may escape at the port.
 
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Cudruln

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Alright please excuse my ignorance, but I have never really gotten into glocks. So when they say small frame pistol magazine, do they mean single stack or what? Pretty much what magazine from what glock will work with this lower? Thanks for helping this dumb ass out.
 

NWS

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Alright please excuse my ignorance, but I have never really gotten into glocks. So when they say small frame pistol magazine, do they mean single stack or what? Pretty much what magazine from what glock will work with this lower? Thanks for helping this dumb ass out.


9mm, 40, 357 sig