I’m looking into a 9mm ar or something similar. Cmmg has a delayed blowback system that seems like a good idea. Anyone on here have one and like or dislike it? Is it any better or worse than a straight blowback system?
Delayed blowback advantages
- Thread starter Geno C.
- Start date
It would be quieter when suppressed. The delay would help with the inherent noise at the ejection port.
Lighter bolt required so smoother pulse when the bolt is cycling as well.
IMHO, the CMMG delayed Blowback is a better concept then straight blowback ( time will tell on the reliability aspect )
Delaying the blowback action, even by milli-seconds , will lessen the "Bark and Blast" from a blowback action.
I delayed my 16" 9MM Colt pattern with heavier recoil spring ( Tubbs .308 Flatwire ) and a heavier 7.5ish oz buffer weight... the drawback from that is heavier reciprocating mass, and a firmer closing of the bolt. I even tried a 10oz buffer weight and Sprinco "orange" ? recoil spring... that setup caused substantial, readily noticable muzzle dip upon the bolt closing.
So , I'd like to think , via mechanical means, the CMMG delayed system is a better "mouse trap" when it comes to PCC's.
Delaying the blowback action, even by milli-seconds , will lessen the "Bark and Blast" from a blowback action.
I delayed my 16" 9MM Colt pattern with heavier recoil spring ( Tubbs .308 Flatwire ) and a heavier 7.5ish oz buffer weight... the drawback from that is heavier reciprocating mass, and a firmer closing of the bolt. I even tried a 10oz buffer weight and Sprinco "orange" ? recoil spring... that setup caused substantial, readily noticable muzzle dip upon the bolt closing.
So , I'd like to think , via mechanical means, the CMMG delayed system is a better "mouse trap" when it comes to PCC's.
It would be great if functional but most adopters we have had at matches ended up with catastrophic breakages. If you want a range toy to punch 500 holes in paper between collecting dust in the safe go for it. The HK is still the only reliable 9mm delayed blowback gun.
If you want a reliable AR9 go with straight blowback like a JP.
I went with the CMMG MK9T 9mm straight blowback and Colt style mags. The delayed version was not available back then. Added a comp to make my timer more efficient and Timney Calvin Elite trigger.
Over 10,000 rounds total and no failures so far.
Over 10,000 rounds total and no failures so far.
I'm seriously thinking of getting a Stribog A3... It's an ugly fucker but it's simple, it's cheap, and it'll make a fun SBR host to a 9mm can I already have. Also, it was featured in Blue Press and apparently AMU reviewed PDW's and rated it among the top. And it's only like $500 something. It's a blowback of course.
I was interested in the CZ until someone told me it has a 12lb. trigger.
Wouldn't mind the HK but for the price? For a semi 9mm? Nope. And the knockoffs generally aren't as good IME. HK makes that civvie SP89 and I like it but damn, couldn't they make it just a little LESS civvie? Goddamn, I don't think you can suppress that thing out of the box and I understand SBR'ing it is next to, if not impossible.
I was interested in the CZ until someone told me it has a 12lb. trigger.
Wouldn't mind the HK but for the price? For a semi 9mm? Nope. And the knockoffs generally aren't as good IME. HK makes that civvie SP89 and I like it but damn, couldn't they make it just a little LESS civvie? Goddamn, I don't think you can suppress that thing out of the box and I understand SBR'ing it is next to, if not impossible.
The hk would be nice but like you said, they’re a little steep for that they are in my opinion too.
From what I have read delayed blow back is better when it works, but a lot of the mechanisms have not been overly reliable, or have wear issues like rollers do. There also are not exactly a lot of them to pick from. If it was always the best chose people would be buying Calico's, since those are roller delayed blow back.
Here's a long thread on the CMMG (yeah it's from ARF) https://www.ar15.com/forums/AR-15/Thoughts-on-the-CMMG-Guard-/15-713060/
Also saw the Dillon article on the Stribog. Looks interesting but cheapest I've seen is ~ $650 on GB. And those are all A1s.
Also saw the Dillon article on the Stribog. Looks interesting but cheapest I've seen is ~ $650 on GB. And those are all A1s.
PTR actually took that concept and made it cheaper and with the stuff you want right out of the box
If you want a shooter & carry gun rather than a collector one, it makes a lot of sense.
Suppressor ready for either 3 lug or threaded, right out of the box.
Especially if you either SBR it or add a folding pistol brace.
Trigger is well.... like a standard HK and you may want to have it worked on.
The cmmg upper is radial delayed blowback and you could drop it right in one of your lowers. Being delayed blowback it's a different animal than a direct blowback ar9
Here you go. A friend of mine bought this for his son and after watching him struggle with catastrophic failures at 2 matches he decided enough was enough and picked up a JP GMR-15. No more issues and both him and his son run it at matches. Typically at least 1 person will have a gun go down and he offers his JP as a backup when that happens now.
When I say the JP 9mm will run I want to explain the full extent of shit we have put it through at matches. We ran a 250 round falling steel match. 4 shooters shot the GMR back to back one after another, suppressed. Not including make up shots, and there were plenty on our little 4" steel plates
, that's over 1000 rounds suppressed in a short period. After the match we used the GMR in a charity man on man shoot off running mirrored 6 plate-plate racks with crossing falling poppers. We also run a 5 stage, 50 shot per stage all paper match that typical stage times range between 15-20 seconds for the faster shooters. Drag racing in high heels at a match like this if you get a jam you're out of the match. All this was suppressed and zero issues. For me it's not a question of saving money. I NEED something that is 100% reliable all the time because odds are good that not only will I use my rifle at a match, but typically at least 1-2 other shooters will be running the gun as well. Nothing ends someone's fun time at a match like a jam or catastrophic failure.
Guard failure point at their "proprietary" cam pin.
I checked out the Angstadt Arms MDP9 at SHOT and it’s pretty dang cool. Pricey, but if it’s as reliable as an MP5, it could be worth it for AR ergos and triggers.
https://angstadtarms.com/mdp9/
https://angstadtarms.com/mdp9/
They took the upper off and briefly showed me, it does have rollers. My apologies though, I’m not an expert by any means on MP5 or other roller mechanisms. They said it is patent (pending?), so it must vary enough to be different from an MP5 or CMMG.
No buffer tube is correct, I asked them about that. Obviously the roller system doesn’t need the tube for cycling, but the buffer tube has more stock/pistol brace options. They said for getting the smallest package possible the Picatinny interface is best. I believe both of their display models used the SB Tactical FS1913 folding pistol brace.
Nice guys, too. I really like what they’re doing.
My approach is to get a PCC when I want a PCC.
Ruger PC9. Mine has the Ruger American Pistol Magazine well option, to coincide with my handgun; so magazines are interchangeable. The takedown feature allows me to carry mine in a sling pack. It's surprisingly accurate with a dot scope.
I run Blaser Brass 124 FMJ, and both firearms like it. I may switch to IMI 115gr JHP. My first two mags for the pistol are loaded with Federal Premium 124 HST.
Greg
Ruger PC9. Mine has the Ruger American Pistol Magazine well option, to coincide with my handgun; so magazines are interchangeable. The takedown feature allows me to carry mine in a sling pack. It's surprisingly accurate with a dot scope.
I run Blaser Brass 124 FMJ, and both firearms like it. I may switch to IMI 115gr JHP. My first two mags for the pistol are loaded with Federal Premium 124 HST.
Greg
I have 2 of them (9mm and .40)
I'm really looking forward to the newly announced Magpul Backpacker stock for them.
I'll definitely change both to that stock as soon as they are for sale.
That stock turned the 10/22 Take down into a whole different level of small packing/carrying.
Also on your 9mm Ruger, try running some of the really hot Fort Scott and Underwood ammo through it. You'll be surprised at how much more energy / penetration you get for anything a bit tougher. It's well worth keeping a mag full of that stuff.
I've been waiting on this!
www.military.com
Magpul Unveils New Backpacker Stock for Ruger Pistol-Caliber Carbine
Magpul's Nylon-polymer PC Backpacker Stock allows the barrel assembly to stow in a cutout on the bottom of the buttstock.
I have a CMMG 45,9mm and 2 5.7's and love all of them. They do seem to be smoother running. Getting ready to use the 5.7 on my m16 with their new AR style 5.7 40rd mags. I was told by them I may need their bolt weights to adjust how they run in FA.
I had an early 9mm Guard (serial 299 if I recall) and I ran through ejector springs pretty frequently. When it ran it was great and even better suppressed but it would go through an ejector spring every few hundred rounds and I'd get double feeds. I sold it and built a straight blow back. I've run it in 2 gun and haven't looked back. I love the concept and maybe I got an early one and it's been fixed but it wasn't reliable enough for me.
Surprised no one has mentioned the B&t APC 9 Pro. Seems to get a ton of love.
Well JP has the regular 9mm stuff backordered with no ETA in sight so good luck with that.
I bet the system is great --if it ever arrives.
I bet the system is great --if it ever arrives.
If I want a Mercedes, then I'd get a Mercedes:
https://www.dakotatactical.com/product/dakota-tactical-d54-10-semi-automatic-10mm-pistol/
Noone does HK clones as well as Dakota. And 10mm out of a 8.9" barrel? Not even 9mm +P+/9mm Major loads would come remotely close to what a properly loaded 10mm is capable of. Another sweet option would be a nice MP5 clone in .357 SIG.. or better yet, 9x25 Dillon!!
Honorable mention, as noted above by @AngryKoala.. altho straight blowback, but B&T's APC line is every bit the quality of HK/Dakota Tactical
https://bt-ag.ch/en/products/bt-firearm-products/apc/
And for some of their offerings that give a bit more bang for the buck:
https://bt-ag.ch/en/products/bt-firearm-products/mp9-tp9/
https://bt-ag.ch/en/products/bt-firearm-products/ghm9/
The GHM9 in particular offers quite a high level of quality/fit/finish for the price from what Ive seen... JMO but while some come close, the HK is considered the Mercedes of the SMG world for good reason. You can currently get the HK SP5 now which is much less civvie-ized than the older HK94 and SP89. But I'd just have to go with 10mm -> delayed roller offering less reciprocating mass than any blowback 9.. and then combined wirh the weight/barrel length on a MP5...doubt you'll see much if any recoil difference vs straight blowback 9's .. muzzle brake would change things, but yiu could always put a brake on the 10 as well....!!!!
https://www.dakotatactical.com/product/dakota-tactical-d54-10-semi-automatic-10mm-pistol/
Noone does HK clones as well as Dakota. And 10mm out of a 8.9" barrel? Not even 9mm +P+/9mm Major loads would come remotely close to what a properly loaded 10mm is capable of. Another sweet option would be a nice MP5 clone in .357 SIG.. or better yet, 9x25 Dillon!!
Honorable mention, as noted above by @AngryKoala.. altho straight blowback, but B&T's APC line is every bit the quality of HK/Dakota Tactical
https://bt-ag.ch/en/products/bt-firearm-products/apc/
And for some of their offerings that give a bit more bang for the buck:
https://bt-ag.ch/en/products/bt-firearm-products/mp9-tp9/
https://bt-ag.ch/en/products/bt-firearm-products/ghm9/
The GHM9 in particular offers quite a high level of quality/fit/finish for the price from what Ive seen... JMO but while some come close, the HK is considered the Mercedes of the SMG world for good reason. You can currently get the HK SP5 now which is much less civvie-ized than the older HK94 and SP89. But I'd just have to go with 10mm -> delayed roller offering less reciprocating mass than any blowback 9.. and then combined wirh the weight/barrel length on a MP5...doubt you'll see much if any recoil difference vs straight blowback 9's .. muzzle brake would change things, but yiu could always put a brake on the 10 as well....!!!!
Last edited:
