Delayed blowback AR

[teratos]

I would love to try one on my MP5 lower.

Not....sure....if....serious.

 

[molonlabe]

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

8 inch. A 45ACP can lose velocity in a 16 inch barrel. That's why the TSMG is 1O.25 inches.

 

[outrider58]

Not....sure....if....serious.

It's an AR lower made for mp5 mags and I am dead serious.

Sent from my XT1585 using Tapatalk

 

[teratos]

It's an AR lower made for mp5 mags and I am dead serious.

Sent from my XT1585 using Tapatalk

Oh. I thought you were gonna try mixing AR and MP5 components. It love to try that too! We can make it happen.

 

[outrider58]

Oh. I thought you were gonna try mixing AR and MP5 components. It love to try that too! We can make it happen.

Sweet!

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[BradMacc82]

8 inch. A 45ACP can lose velocity in a 16 inch barrel. That's why the TSMG is 1O.25 inches.

Saw that in the link Doc posted, seems after 14 or so inches, velocity starts dipping down. Makes that choice easy!

 

[slowpoke]

Now this looks a fun diversion for 2018. Looking forward to hearing about how the build works out.

 

[jimbobborg]

There are several guys here http://forums.brianenos.com/topic/255670-anyone-tried-the-new-cmmg-guard/ who have tried and tested these.

 

[photoracer]

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.

Just buy a CZ Scorpion. Anything with an AR charging handle suppressed is going to give you some gas and debris blowback into your face, unless you go with a side charging upper like a Spartan or similar one that does not use the charging handle.

 

[teratos]

Just buy a CZ Scorpion. Anything with an AR charging handle suppressed is going to give you some gas and debris blowback into your face, unless you go with a side charging upper like a Spartan or similar one that does not use the charging handle.

Scorpion is direct blowback. Delayed blowback will reduce the gas blown back. The large volume suppressor I am going to put on it (11.5” tube, reflex design) should fix the rest.

 

[JC82]

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

The one I ordered should be here next week!

 

[GolfR]

I struggle a bit with 45 acp ARs. I would like to get one but find it hard to justify when I have several 300 blk the shoot 245 gr loads and 9mm uppers with a colt mag block. 300 blk is basically the same energy as 45 acp but I don’t have to worry about dedicated lowers, new mags, etc. I can also use my 9mm supressor! I’m not saying that I don’t want one, but 1k+ for an upper lower combo, 600+ for a 45 supressor, 100+ for mags. Getting into a 45 acp AR would be an expensive endever and I wouldn’t be able to use my SBR lower with a mag block like I do with 9mm.

I do wish that they made a delayed blowback 9mm upper in 11 inches so that I could use it on my SBR in MD. I think it would be more pleasant to shoot, cleaner and quieter when suppressed.

 

[teratos]

You could buy the 16" barrel/bolt and have it cut.

 

[GolfR]

That’s a possibility but it runs over $100 to have a barrel cut and threaded.

 

[teratos]

That’s a possibility but it runs over $100 to have a barrel cut and threaded.

8" barrel and pin/weld the suppressor mount?

 

[erwos]

8" barrel and pin/weld the suppressor mount?

I measured my Navy 3lug mount, and it only added about .75". Presumably, pinning that plus the combo of Magpul ACS-L plus Vltor A5 plus Magpul 0.7" buttpad will get you there. You'll have a bit of an expensive monstrosity at the end... frankly, chopping the 16" barrel to 10.5" is going to be cheaper than doing all that other stuff.

I did some more research, and it turns out this system is not compatible out of the box with guns that are using Colt double-feed mags. CMMG said that they were going to return to the problem in late-2018/early-2019, as, obviously, there is a huge market for retro-fitting old Colt-style guns with something better than direct-blowback.

 

[teratos]

I got my bolt/barrel in today. Definitely a no-go on a Colt pattern lower. The raised feedramps aren’t liking the basically standard sized BCG. I have an 80% Glock lower I’ll mill out later this week and try out over the weekend.

 

[BradMacc82]

I'll be waiting to hear the results. Haven't bought anything yet, I'm letting you guys be the guinea pigs.

 

[teratos]

I'll be waiting to hear the results. Haven't bought anything yet, I'm letting you guys be the guinea pigs.

Thinking of getting a decibel meter to compare direct blowback vs delayed. Particularly interested in the ejection port noise. I can use my Multimount on both my 9mm ARs.

 

[BradMacc82]

Thinking of getting a decibel meter to compare direct blowback vs delayed. Particularly interested in the ejection port noise. I can use my Multimount on both my 9mm ARs.

I'm guessing delayed ought to be good for a few decibels over direct, maybe not a huge difference, but again I'm just guessing.

I have to get my list together so I can get working on that. Have the links for the lower and the tube, and bolt/barrel - but that's about it for the moment.