I have dabbled in 9mm carbines for the last couple of years, purchasing a Ruger PC Carbine and a PSA AR9. I was unsatisfied with both of them for numerous reasons, but my primary complaint is with the blowback design as a whole. The heavy bolts, harsh recoil (for a 9mm), filthy dirty operation, and general unsophistication are turn-offs for me. I also had some issues with the AR9 running a 9mm in a .223-length action(hammer follow and OOB discharges just because you changed ammo and the new ammo is short-stroking the action just isn't cool).

Both of those are now gone...traded down the road for better things. But this leaves me without a semi-auto PCC in the collection, and I really want one...but I don't want it to be straight blowback (rules out AR9s, PC9, Camp 9, NAK9, Skorpion Evo, Chiappa 9mm M1 Carbine, etc), and I want it's action to be purpose built for the cartridge that it's firing (I thought about the CMMG Guard, but even being delayed blowback it still relies on buffers and a rifle-length action).

Options I've considered are the MPX, MP5 clones like the PTR, and of course the H&K SP5. Unfortunately, these are all outrageously expensive, but so far I haven't seen any other options. Is there anything out there I'm missing? And if not, why is nobody making a gas-operated or locked-breech PCC in the $700-$1000 range? Is it really that much more complicated that it justifies the $1800-$2500 price tag? Or are Sig and H&K getting away with those prices simply because they're the only game in town? You'd think that with the increasing popularity of PCCs these days, somebody would come up with something like this...

ETA:

Sorry, just saw you already considered the CMMG. I missed that.

There are guys on ARFcom who have played with tons of springs and buffer combos who say that they have their CMMG guard running smooth as an MP5.

It’s easier and cheaper to make a simple blowback 9mm than a delayed blowback or gas operated 9mm, so they are going to cost more. The CMMG guard is probably going to be the best option, either with CMMG’s lower, or with the CMMG upper on a standard AR lower using Endomags.

quote:

Originally posted by IndianaBoy:
There are guys on ARFcom who have played with tons of springs and buffer combos who say that they have their CMMG guard running smooth as an MP5.

I wouldn't dispute that, but I imagine that reliable operation would require sticking with a very specific brand and weight of ammo. I played the buffer game for a while with the AR9, and while you can make things run smoothly, the second you change ammo (or any number of other factors), you're starting all over again.

I also don't like how the blowback AR has no provision in the action to prevent an OOB discharge. The long action can easily allow a short-stroke situation in which the gun will extract and eject the fired round, begin to chamber another round, yet fail to have enough rearward bolt travel to engage the disconnector, resulting in hammer-follow and doubling, or even an OOB discharge.

When you're working on tuning the gun, the objective is to put in enough buffer and spring to slow that rearward impulse, but still retain enough rearward travel to engage that disconnector every single time. It's pretty much a a balancing act, and IMO there's just too much room for error in the system. I'm sure there are guys with enough mechanical knowledge out there to get it perfect, but experience has dictated that it's not for me.

quote:

Originally posted by Dwill104:
It’s easier and cheaper to make a simple blowback 9mm than a delayed blowback or gas operated 9mm, so they are going to cost more.

Understandably. But 3-5x more??? it seems like there should be some room in the middle open for development.

quote:

Originally posted by 92fstech:
Understandably. But 3-5x more??? it seems like there should be some room in the middle open for development.

Go for it!

quote:

Originally posted by 92fstech:

quote:

Originally posted by IndianaBoy:
There are guys on ARFcom who have played with tons of springs and buffer combos who say that they have their CMMG guard running smooth as an MP5.

I wouldn't dispute that, but I imagine that reliable operation would require sticking with a very specific brand and weight of ammo. I played the buffer game for a while with the AR9, and while you can make things run smoothly, the second you change ammo (or any number of other factors), you're starting all over again.

I also don't like how the blowback AR has no provision in the action to prevent an OOB discharge. The long action can easily allow a short-stroke situation in which the gun will extract and eject the fired round, begin to chamber another round, yet fail to have enough rearward bolt travel to engage the disconnector, resulting in hammer-follow and doubling, or even an OOB discharge.

When you're working on tuning the gun, the objective is to put in enough buffer and spring to slow that rearward impulse, but still retain enough rearward travel to engage that disconnector every single time. It's pretty much a a balancing act, and IMO there's just too much room for error in the system. I'm sure there are guys with enough mechanical knowledge out there to get it perfect, but experience has dictated that it's not for me.

I think you might have mistake what I was saying.


They aren't playing with buffers to get it to run right. They are playing with buffers to get it as smooth as an MP5.


The CMMG does have protections from OOB discharge. It is not blowback. The bolt rotates when it unlocks. It doesn't lock again until it is back in battery, and at that point the firing pin can make contact with the primer again.

It has the same OOB discharge protection as a 5.56 AR15.

As for ammo, I have run mine with factory WWB as well is my minor power factor USPSA loads and it digests them all.


My AR pistol lower that I am using is the same one that I am using with a 11.5 suppressed 5.56 upper. It has a standard spring and an H3 buffer.

It is anything but finicky.

ETA:

It also has a spring on the forward portion of the firing pin, eliminating the floating firing pin typical of most AR15s.


I have done no 'tuning' to make mine run right.

I put it on my existing 5.56 pistol lower, slapped in a 30 round endomag, and started shooting.

It was surprisingly accurate.

It doesn't meet all of your criteria but it is soft shooting & within your price range.

https://palmettostatearmory.com/ak-47/ak-v.html

quote:

Originally posted by 92fstech:
but still retain enough rearward travel to engage that disconnector every single time. It's pretty much a a balancing act, and IMO there's just too much room for error in the system.

Because of the way the firing pin works, if you ever didn't engage the disconnector, you would just wind up with a dead hammer, not an OOB.


I have never had a dead hammer.

quote:

I have done no 'tuning' to make mine run right.

I put it on my existing 5.56 pistol lower, slapped in a 30 round endomag, and started shooting.

Ok, now I'm kind of intrigued...I think I had some misconceptions about how the guard worked. How has the endomag worked for you? Does it have lrbho?

The CMMG radially delayed blowback AR/9 is great. We (07/02 FFL/SOT) have a couple on post sample m16 lowers that are used with Endomags. They run great, both unsuppressed and suppressed. It’s a very nice design. We have many other SMGs from which to choose and the CMMG RDBB is among our favorites.

It has AR ergos (it’s an AR) and LRBHO on the endomag. You need to be sure you buy the correct Endomag that lacks a fixed ejector.

Not a fan of the CMMG handguard. You can buy the barrel and bolt group from CMMG, then buy an Aero XL upper (larger ejection port) and assemble yourself with your desired handguard.

All that said, you also need an MP5 and while the SP5 is expensive, in a few years when no more are imported you will wish you’d bought one (or two). Buy an SP5.

I know nothing of the PSA personally but I think its a blowback gun... from PSA..."The PSA AK-V is a blowback-operated system to ensure a smooth cycling action."

quote:

Originally posted by IndianaBoy:

quote:

Originally posted by 92fstech:

quote:

Originally posted by IndianaBoy:
There are guys on ARFcom who have played with tons of springs and buffer combos who say that they have their CMMG guard running smooth as an MP5.

I wouldn't dispute that, but I imagine that reliable operation would require sticking with a very specific brand and weight of ammo. I played the buffer game for a while with the AR9, and while you can make things run smoothly, the second you change ammo (or any number of other factors), you're starting all over again.

I also don't like how the blowback AR has no provision in the action to prevent an OOB discharge. The long action can easily allow a short-stroke situation in which the gun will extract and eject the fired round, begin to chamber another round, yet fail to have enough rearward bolt travel to engage the disconnector, resulting in hammer-follow and doubling, or even an OOB discharge.

When you're working on tuning the gun, the objective is to put in enough buffer and spring to slow that rearward impulse, but still retain enough rearward travel to engage that disconnector every single time. It's pretty much a a balancing act, and IMO there's just too much room for error in the system. I'm sure there are guys with enough mechanical knowledge out there to get it perfect, but experience has dictated that it's not for me.

I think you might have mistake what I was saying.


They aren't playing with buffers to get it to run right. They are playing with buffers to get it as smooth as an MP5.


The CMMG does have protections from OOB discharge. It is not blowback. The bolt rotates when it unlocks. It doesn't lock again until it is back in battery, and at that point the firing pin can make contact with the primer again.

It has the same OOB discharge protection as a 5.56 AR15.

As for ammo, I have run mine with factory WWB as well is my minor power factor USPSA loads and it digests them all.


My AR pistol lower that I am using is the same one that I am using with a 11.5 suppressed 5.56 upper. It has a standard spring and an H3 buffer.

It is anything but finicky.

ETA:

It also has a spring on the forward portion of the firing pin, eliminating the floating firing pin typical of most AR15s.


I have done no 'tuning' to make mine run right.

I put it on my existing 5.56 pistol lower, slapped in a 30 round endomag, and started shooting.

It was surprisingly accurate.

The guy playing with buffers is amphibian on arfcom. His entire goal is to get the Cmmg running slow enough on FA that he can easily pull singles during SMG matches in which he competes. My business partner set up one of ours with A5 receiver extension, Tubb flat wire spring, and A5H3 buffer. It’s very very smooth shooting on full auto. Not quite as smooth as my MP5s, but very close and with better ergonomics and far less expense.

A couple of questions. What is OOB?
Second is can you buy a Guard upper and will it mount to a std. Cmmg AR9 lower?

Thanks.

I'm a bit of a 9mm rifle addict. Have you shot any of the non blowback 9mm choices you are asking about? I ask as I happen to own the HK, MPX and CMMG (this as a pistol, but I shoot it in rifle classes). I also happen to own several blowback AR's (primarily colt ones) and other 9mm blowback designs (scorpion, IWI, PTR, etc.) I've shot thousands and thousands of 9mm rounds in these and not once while shooting did I say to myself that was harsh recoil. Semiauto. Nor would I say the difference is meaningful or material between the designs at least while trying to shoot competitive matches. I simply don't notice. That said.
I happen to really like the CMMG as the best of your choices at least price wise. And its easy enough to buy just the necessary parts from them and reuse AR stuff you likely have and the price is quite reasonable (The HK however will probably be the best long term bet if you can stand the price of admission and the upfront costs (like $75 mags).

quote:

What is OOB?

out of battery.
The answer to your CMMG question depends slightly on which mag type is your lower.

quote:

Originally posted by 92fstech:

quote:

I have done no 'tuning' to make mine run right.

I put it on my existing 5.56 pistol lower, slapped in a 30 round endomag, and started shooting.

Ok, now I'm kind of intrigued...I think I had some misconceptions about how the guard worked. How has the endomag worked for you? Does it have lrbho?

The endomags have been great. LRBHO works as it should, and the lower I am using it on has a Magpul BAD lever which some people contends can interfere with LRBHO.

Thanks hrc, I have a factory cmmg 9mm AR lower. So Colt mag design