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Posted: 4/20/2016 1:26:28 AM EDT
This may have been covered in another thread, but I wasnt able to finding anything that answered my question.
Im planning on building a 9mm AR w/ a 7.5 bbl.   I was wondering in what way this would affect suppressing the gun?
I dont own a suppressor, but am planning on one after i get this build out of the way... and a wedding...  either way I know next to nothing about suppressors other than they make loud bangs less loud.  Am i going to run into any issues suppressing 9mm out of this barrel length?
Link Posted: 4/20/2016 1:42:46 AM EDT
Lots of people use a 7.5" barrel and it should stay subsonic with 147gr or larger.


I prefer 4.5 cause I wanted a short barrel rifle to be short!  And it is suppressed 100% of the time.
Link Posted: 4/20/2016 2:06:48 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Lots of people use a 7.5" barrel and it should stay subsonic with 147gr or larger.


I prefer 4.5 cause I wanted a short barrel rifle to be short!  And it is suppressed 100% of the time.
View Quote


This.

Standard pressure 147s will be subsonic out of 5" (or shorter).

Add a 6-7" can to a 7.5" barrel and you're back up to full size M4 length.
Link Posted: 4/20/2016 10:54:25 AM EDT
As others stated go short if you're planning to suppress. I have a 5" barrel and wouldn't go any longer than that.
Link Posted: 4/20/2016 10:42:09 PM EDT
I run a 7.5" subgun with handloads and AWC Mk9 can,, no concerns.. load accordingly

Run a 10 1/4 Uzi also.. all depend on load make up..
Link Posted: 4/20/2016 11:42:07 PM EDT
From 4"-10" barrels have proven to work with 9mm suppression reliably. I have a 5.5" barrel and a 10.5" barrelled uppers and have no problems suppressing either. I also experience a less dirty suppressor with the 10" but slighly more blowback/port bark.
Link Posted: 4/21/2016 10:07:12 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Lots of people use a 7.5" barrel and it should stay subsonic with 147gr or larger.


I prefer 4.5 cause I wanted a short barrel rifle to be short!  And it is suppressed 100% of the time.
View Quote



Absolutely correct.
OP you will be super pissed every time it cracks with the 7.5".
I use a 4.5" on my 9 mm shorty's. And I use 147's all the way down to -15 with no crack.

Dumped the first 7.5" I assembled. Cracked with 147's . Pointless
Link Posted: 4/21/2016 10:28:39 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Quoted:


OP you will be super pissed every time it cracks with the 7.5".
I use a 4.5" on my 9 mm shorty's. And I use 147's all the way down to -15 with no crack.

Dumped the first 7.5" I assembled. Cracked with 147's . Pointless

View Quote



Factory loads, or handloads ??

I have only used 1 box of factory stuff, that was Winchester 147gr Silvertip self defense.. all I use anymore is handload with 147gr bullets via 7.5" M11/9 with stainless SAAMI chambered barrel, and Uzi 10 1/4 barrel,, both with AWC Mk9
Link Posted: 4/22/2016 10:51:08 PM EDT
Winchester W 147s go super in my CMMG 8" barreled AR. Fiocchi and PPU 158s stay subsonic and are fairly quiet.
I'm tempted to replace the 8" with a 4.5" barrel, but it runs so well now that I don't want to mess with it.
Link Posted: 4/23/2016 11:51:05 PM EDT
Appreciate all the replies.  Exactly the information I was looking for.
Link Posted: 4/24/2016 12:54:30 AM EDT
Personally, I'm getting arfcoms favorite: both. Been wanted to do a DOE retro style so I went with the 7.5 while I wait for paperwork to build a supressed 4.5.
Link Posted: 4/24/2016 2:49:04 AM EDT
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