Delayed blowback AR

teratos · Dec 24, 2017

https://www.cmmginc.com/product-category/rifles/9mm-guard-rifles/

CMMG has a "radial delayed" blowback 9mm and .45 ACP AR. No more heavy buffers/springs. Reduced recoil. Should be a better suppressor host with less ejection port bark. The complete rifle isn't priced terribly, but you can buy a bolt/barrel for <$400. Not sure it will work with Colt pattern mags. I'll let you know when I get my barrel/bolt in.

BradMacc82 · Dec 24, 2017

Offered in .45ACP? Now you have my attention.

teratos · Dec 24, 2017

BradMacc82 said:
Offered in .45ACP? Now you have my attention.

The .45 came out first!

BradMacc82 · Dec 24, 2017

teratos said:
The .45 came out first!

I just have to decide, 8" or 16" barrel.

teratos · Dec 24, 2017

BradMacc82 said:
I just have to decide, 8" or 16" barrel.

8" . Why would you NOT suppress it. That barrel/bolt combos are available under barrels. Not sure what lowers would be compatible, though. I found the EXACT lower they use for the 9mm as an 80%.

John from MD · Dec 24, 2017

Dang, I would have to go back to work at those prices.! I guess I stick with my Kel Tec Sub 2000. :envy:

teratos · Dec 24, 2017

John from MD said:
Dang, I would have to go back to work at those prices.! I guess I stick with my Kel Tec Sub 2000.

Consider what other 9mm carbines are available in a delayed blowback config and compare prices.

Inigoes · Dec 24, 2017

You might be able to find a marlin camp carbine at a reasonable price.

teratos · Dec 24, 2017

Inigoes said:
You might be able to find a marlin camp carbine at a reasonable price.

They are direct blowback.

lennyk · Dec 24, 2017

I was following this one from CMMG as well. Please keep us posted. Would be a sweet pistol build. The mag issue is important. The glock pattern systems don't seem to have good last round open feature. Colt pattern systems seem to do much better for that. The bolt catch operation is more robust.

https://www.cmmginc.com/product/barrel-and-bcg-kit-8-4140cm-sbn-9mm/

teratos · Dec 24, 2017

lennyk said:
I was following this one from CMMG as well. Please keep us posted. Would be a sweet pistol build. The mag issue is important. The glock pattern systems don't seem to have good last round open feature. Colt pattern systems seem to do much better for that. The bolt catch operation is more robust.

I'm going to try it on my Colt pattern lower. I have tried using google-fu to see if anyone had tried, and can find nothing. We'll see. I have a 9mm upper that has been sitting in my safe for years, so I should be able to test relatively soon after getting the bolt/barrel. Just ordered it today.

BradMacc82 · Dec 24, 2017

teratos said:
8" . Why would you NOT suppress it. That barrel/bolt combos are available under barrels. Not sure what lowers would be compatible, though. I found the EXACT lower they use for the 9mm as an 80%.

I'm just doing the mental math on how much velocity a 230gr fmj would gain in a 8" barrel vs a 4.5/5", should still come in under 1060fps (I think).

teratos · Dec 24, 2017

BradMacc82 said:
I'm just doing the mental math on how much velocity a 230gr fmj would gain in a 8" barrel vs a 4.5/5", should still come in under 1060fps (I think).

http://www.ballisticsbytheinch.com/45auto.html

The only thing better than this for suppression would be a De Lisle repro....

BradMacc82 · Dec 24, 2017

That settles that.

Boss94 · Dec 24, 2017

It also states,to be used on there lower and upper :-( I have a lower from a company in Florida. They gave me the chance to order direct blow back or delayed.I'm not sure how the lower is different but it must be something for them to ask what I was building to give me the right lower for it ? I'm still waiting on putting that 1 together. When PSA has the uppers im short on cash. When I have the cash they are out of stock. Feel like a cat chasing it's tail.

teratos · Dec 24, 2017

Boss94 said:
It also states,to be used on there lower and upper :-( I have a lower from a company in Florida. They gave me the chance to order direct blow back or delayed.I'm not sure how the lower is different but it must be something for them to ask what I was building to give me the right lower for it ? I'm still waiting on putting that 1 together. When PSA has the uppers im short on cash. When I have the cash they are out of stock. Feel like a cat chasing it's tail.

Only tested with their lower. I have an 80% Glock mag lower, and a Colt pattern lower. Going to try it.

Boss94 · Dec 24, 2017

teratos said:
Only tested with their lower. I have an 80% Glock mag lower, and a Colt pattern lower. Going to try it.

Let us know how it goes. Would love to get mine buttoned up . Thanks !!

erwos · Dec 24, 2017

I'm definitely interested, too. Want to run one of these on my 9mm Uzi-mag build. Direct blowback is alright, but I'd like to lighten things up by moving to delayed blowback.

Knowing CMMG, it probably works just fine on any "mil-spec" lower, but I understand why they'd be reluctant to guarantee it.

teratos · Dec 24, 2017

Boss94 said:
Let us know how it goes. Would love to get mine buttoned up . Thanks !!

Will do! The 80% lower I got looks (and probably is) the exact same thing as the CMMG lower. I’m sure there are people here that would be happy to let you use their jigs.
I believe it’s legal as long as there is no money changing hands. https://www.wolfpackarmoryusa.com/product-page/cerakoted-ar9-80-lower-receiver

erwos said:
I'm definitely interested, too. Want to run one of these on my 9mm Uzi-mag build. Direct blowback is alright, but I'd like to lighten things up by moving to delayed blowback.

Knowing CMMG, it probably works just fine on any "mil-spec" lower, but I understand why they'd be reluctant to guarantee it.

Yeah. Most 9mm uppers work fine with any lower. I’m most interested in whether this works with my Colt lower. It’s a SBR lower. I plan to make the upper integrally suppressed.

outrider58 · Dec 24, 2017

I would love to try one on my MP5 lower.

Delayed blowback AR

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