You should.


A few years back at the NRA show, CMMG was running a show special on their radially delayed blowback PCCS. I can't recall if it was 40 or 50% off, but it was substantial. At the time I think they called them the 'Guard'. They have since changed to the name to Banshee but it is still the same operating system. Instead of using mass and a heavy spring to retard the opening of the bolt, they developed a system with radius cut lugs on a traditional AR bolt, and a slightly altered cam pin path on the bolt carrier. This results in a carrier and buffer mass that is 40% less than standard straight blowback 9mm AR.

I opted for their version that runs on a standard AR lower using magazine inserts from MEAN Arms called endo mags. You pull the guts out of a standard PMAG and slide in this insert. Works like a charm and I have never had a malfunction yet. I have fired almost 1000 rounds through it in the last two weeks. They also have offerings that use Glock mags or the Colt SMG mags.

Some people claim that with tuning using different buffers and springs, that this system can be as smooth as the HK roller locked MP5 which has always been the gold standard for a smooth operating 9mm carbine. I am currently just using a standard carbine spring and an H2 buffer. I will be playing with different buffers soon.

Now I don't own an MP5 and have only shot one once or twice, although I will be fixing that on Tuesday as a friend who has one will be visiting and I will be able to shoot both side by side.

Anyway, that CMMG PCC sat in my safe for two years before I got around to finally ordering a silencer for it, I bought the version with the 5" barrel as I had only ever intended to shoot it suppressed. I took it out when new and fired a few mags through it to make sure everything worked properly, and it did. But I never spent much time with it.

Big mistake waiting so long to get the ball rolling on my suppressor. I finally pulled the trigger on a Rugged Obsidian 9mm silencer and oh boy..... What an awesome setup. The delayed blowback with this setup dramatically reduces ejection port noise that you might get with a direct blowback PCC that opens immediately upon firing.

This thing is probably going to almost every range trip this summer and going forward. What an immensely fun gun to shoot. Easy offhand hits on BC zone sized steel out to 125 yards. Cleaning plate racks in times that I could never do with a pistol. Perfect training gun for new shooters where the blast from a 223 AR might be off-putting. And I can now shoot all my steel with a rifle platform without damaging it at less than 100 yards.


If you have been considering a 9mm AR. Build or buy one and get the can process started now. ATF took 290 days to approve my Form 4.


Pics and video will be coming.

I had a RRA Colt SMG copy for a while. I didn't shoot it much, sold it, and don't miss it. I never felt like a 9mm AR was a suitable "training substitute", as some advocate, and I often struggle with the idea of a semi-auto SMG. I won't argue with you, when it comes to the fun factor, but if I'm gonna have a semi-auto SMG for fun, I'd like it to be an SP5, because of the awesome history associated with that weapon. The PCC no doubt has it's place in certain circumstances, for certain folks, but I have yet to find myself being one of them. I think the CMMG operation is cool; seems like a cost-effective enhanced system, when most blowback alternatives get much spendier. Considering your mention of suppression, and this being in the suppressed forum, I'll add that I did shoot mine with a Ti-Rant9, and it was pretty slick. Miles better than an AUG I had at the time, with the 9mm conversion. 9mm bullpup=NO-GO with a can; 9mm is one of the calibers that can be quite quiet indeed, with a silencer, and the action being right next to your ear cancels that benefit right out. Sold all that too; the conversion kit was one of the few things I ever made money on; don't miss it. I honestly wouldn't mind having the AUG itself back, but I'd prefer a STANAG mag model nowadays.

I have a CMMG RDB build, using a standard lower and the conversion mags, and I can attest that it's just an absolute hoot to shoot. Recoil impulse is similar to, or maybe a bit lighter than a .223, without the muzzle blast, and it's awesome fun to shoot on steel. I can shoot offhand on the 6" plate rack from 50 yards, or closer if I want to, and not have to worry about tearing stuff up. It's probably my favorite AR for fun range time.

Like IndianaBoy said, it's smooth. I don't have an mp5 to compare it to, but I shot it side by side with an MPX, and recoil impulse was very close to the same...more than close enough considering it was half the price. And my gun is lighter, even with a 16" barrel compared to the 8" MPX. I had a straight blowback PSA AR before I built this one, and they were absolutely nothing alike.

The CMMG did eat an ejector spring and pin at about 1000 rounds. Easy fix, and I installed the CMMG supplied bolt weights which seem to have fixed the problem. I'm currently about 1500 rounds into the new spring...if it breaks again I'll just replace it again with $3 worth of stuff from the parts box.

I can only imagine that these things are awesome suppressed. I'm still waiting on the ATF to let me have my first can (a .22)...but the next one's going to be 9mm, just because of this rifle.

Its not too often KSGM and I don't see things the same, but in this case we don't. A 9mm AR is just about the perfect lower cost substitute for a full power AR and training for just about everything but long range shooting. Same just about everything in terms of the gun. You can literally run the same lowers and triggers, same uppers and glass sights lights whatever, same NVG, same everything. Just less cost per round and range. What about it might not be suitable I have no idea. And at least in my area we can do drills/training/fun things that would never be possible with a 5.56 or .308. just because of the difference in ballistics. I may be the quintessential owner of 9mm PCC stuff, I literally have them all (note some might think that's an exaggeration but its not). Some complain about the recoil differences. They are silly IMO. But as a rule I run everything suppressed and 9mm does really well with that. And short barrels don't bother it.
These are extremely versatile and fun guns for any use and any body.

Yes yes yes and yes!!


Need to try out this Aero EP-C I built. It's gonna get SBR'd and SHH'd as soon as I get off my ass.

These are blow back but Im hoping a .45 can will mitigate that. Aero had this sale going on, see... and it uses Glock mags see...

Why must I be so damn busy?

9mm carbines are nice. I shot an MP5 many years ago at an indoor range, with lanes up to 50 feet. The MP5 cycled smoothly, but I didn't like the ergonomics and honestly I shot my Sig X5 and 1911s more accurately. The MP5's owner seemed a bit taken back that I didn't think the MP5 was the greatest thing since sliced bread.

A few years ago I bought a Wilson Combat 9mm SBR. 8" barrel and Omega K can. This is a great carbine for AR15 training. Significantly lower ammo cost than 223, noticeably less recoil than 223, doesn't damage steel targets at short distances, is really quiet with subsonic ammo, is surprisingly accurate. I'll put this WC against any brand of 9mm PCC anytime, anywhere.



Here is 10 rounds of S&B 115 grain FMJ at 200 yards in breezy conditions at 200 yards from prone. 2.5" vertical variation. That's 1.25 MOA with FMJ ammo -- few rifles of any caliber can pull that off.



I've used this AR9G for a bunch of drills in the Sigforum "Postal Match". It performs well, and I'm faster with it than with any of my AR15s. Here are a couple of targets -- controlled pairs and triples on 3x5 inch cards, from low ready, at 3-25 yards.

Another example from the Sigforum "Postal Match" -- page 17, where I was doing my own drills.

Back to the 3-25 yards with a carbine drill, with 3x5 cards as targets. This time with a pair on each of two targets. I ended up setting the 3x5 cards 32" apart -- I measured after shooting. I had one miss on each card -- 9 o'clock on the right target and 3 o'clock on the left target. The misses occurred at either 20 or 25 yards. From the same high ready we used a few weeks ago. 2 shots on the right, then 2 shots on the left target. 9mm AR SBR again.

How the targets looked right after shooting:



And with them parked next to each other:



For all seven distances my splits averaged
1.02 + .46 + 1.05 + .39 = 2.92 seconds

I did noticeably better at distances of 3, 5, 7, and 15 yards. Splits here averaged
.83 + .39 + 1.03 + .30 = 2.55 seconds.

Not my speediest at 10, 20, and 25 yards. Burned only 1 tank of fuel with the chainsaw prior to shooting -- not certain if it made much difference. Transitions aren't the easiest thing to do.

Man, I have been a dissenting voice around here lately. When it comes to the 9mm carbine as a 5.56 training substitute, am I to understand that those of you who are fond of the concept shoot the 9mm carbine more than it's 5.56 counterpart?

quote:

am I to understand that those of you who are fond of the concept shoot the 9mm carbine more than it's 5.56 counterpart?

Probably about equal for me, as it depends what I'm doing. For distance work, or anything on our rifle bay (goes out to 200 yards), I primarily shoot the 5.56. If that bay is occupied, or I want to do something high-speed and close in on steel, I use the 9mm. Our club only has one bay where you can shoot rifle calibers, but PCCs in pistol calibers are allowed on several of the other bays, so it gives me a lot more flexibility to have the 9mm along on a range trip.

I actually took a new shooter along this week and let him shoot several different guns, including an M16 clone and the 9mm PCC. The 9mm was his favorite, and he did quite well with it.

If I had a can, I'd probably shoot the 9mm even more, as it will suppress far more effectively than a 5.56.

I certainly shoot mine more. Why? because lots of stuff we can do is on steel and close and in the depths of winter inside. Would not work with rifles in rifle calibers.
I get its not a complete substitute. But I do force myself to lob a few rounds downrange inside on a regular basis to make sure I remember how unfriendly a short barreled (even suppressed) rifle caliber gun is.

quote:

Originally posted by KSGM:
Man, I have been a dissenting voice around here lately. When it comes to the 9mm carbine as a 5.56 training substitute, am I to understand that those of you who are fond of the concept shoot the 9mm carbine more than it's 5.56 counterpart?

Not necessarily more because I enjoy long-ish range with a carbine but the ability to shoot steel without damaging it from an AR platform is very very appealing.


It is definitely much easier to shoot well at pistol caliber distance with a PCC than a handgun.

I see; it's making more sense now. It seems close-range steel is a big factor; I don't have anything like that set up, so it's paper for me, and a non-issue. The indoor training advantage makes sense too.

Steel has the advantage of immediate audio & visual feedback that the target was hit. Painted steel provides immediate visual feedback where the target was hit. Painted steel's feedback advantages include:
- If follow through occurred after the shot. One can see if sights stayed on POA. This is a test of the fundamentals.
- If the shooter judged wind correctly.
- If the shooter held elevation correctly, and if the rifle/ammo is consistent in elevation POI. IMO this is the single most important factor in long range precision shooting.

There's no feedback delay with steel. If the shooter's fundamentals are sound, the shooter will have eyes on target and actually see the bullet impact the steel. I credit the immediate feedback loop of shooting on painted as a significant part of my skills improvement over time.

I understand and appreciate most of the advantages of steel, painted or not. I do use steel for a couple different targets; one sees use between 50 and 100m, and the other 100m to 400m. I just don't have any more that get used close-range; I assume 25m and closer is what folks are referring to, in the context of PCC use.

quote:

Originally posted by KSGM:
I understand and appreciate most of the advantages of steel, painted or not. I do use steel for a couple different targets; one sees use between 50 and 100m, and the other 100m to 400m. I just don't have any more that get used close-range; I assume 25m and closer is what folks are referring to, in the context of PCC use.

Yes.

I have a wide assortment of steel set close for pistol use. Being able to use an AR to shoot that, with the same lower and trigger as my defensive AR, provides an opportunity to train on steel at close range without damaging the steel and at lower cost than with 5.56.

Being suppressed with subsonic 9mm ups the fun factor and nobody knows I'm shooting. Not a big issue because I don't have close neighbors but it also saves my hearing.


My neighbor brought his daughter over to shoot. Very much a novice, and she was regularly hitting steel that I doubt she would have been able to hit with a traditional pistol.

Well, you might have convinced me to get off my butt and get a Rugged Obsidian. I've been eyeballing one for my first can, and I think I'm down to whether I want to get 9mm or 45. Everyone says get a .30 cal can, .45, and a .22. I get the practicality of it, but I'll be damned if I'm not heavily leaning towards a 9mm. I have a .40, but everything else is in 9mm or .380.

Anyway, the Form 1 for the Scorpion is waiting to come back, and I think the Obsidian, a tri lug, and I'm off and running.

That said, I have always been intrigued with integrally suppressed guns, and this thing is stupid expensive, but it shoots standard velocity ammo at subsonic velocities in a package only a couple inches longer than mine is without a suppressor.

About the MP5, a good friend of mine built one up off a kit and SBR'ed it. He wanted one for years and finally made it happen. A few months after getting the paperwork back and putting a stock on it, he was totally and completely over it. I shot it at the range once, and like fritz, was totally underwhelmed. Had that classic HK 15lb trigger and was like a much smaller, much less useful version of my HK91. I put ten or so rounds through it, handed it back to him and shrugged. He shrugged and it went back in the case. He still remarks every once in a while that it's the only gun he still owns that he doesn't like in the slightest. At least with the Scorpion, the ergonomics are a little better, or at least a little easier to change. Triggers, too. I look at it as the spiritual successor to the MP5. I know, blowback vs roller locked and all that, but the vibe is there, but newer and cleaner feeling.

In regards to that Innovative Arms Scorpion upper: I don't know how sensible it is to shoot lighter bullets slower. When the MP5SD was a thing, it was likely slick because it caused no logistical changes, when it came to ammo. But nowadays, with the broad ammo selection, why shoot 115 or 124, when you can shoot 147? I guess something can be said for shooting it all, if one's not available, or one's significantly cheaper than another. I believe the MP5SD ran into problems, if you did shoot subs through it; is that Scorpion similarly afflicted? I have had the pleasure of shooting an MP5SD; I thought it was effin' cool. It was a proper sub-machine gun though; that'll make anything cooler. I will not deny that I have a little "fan boy" in me, when it comes to the MP5; same with the P90. I own neither though, because I ultimately can't logically justify such an expenditure at this time.

quote:

Originally posted by P220 Smudge:


Anyway, the Form 1 for the Scorpion is waiting to come back, and I think the Obsidian, a tri lug, and I'm off and running.

100% get the tri-lug.

A buddy of mine with an MP5 is waiting on stamp approval of a Dead Air Wolfman and he is planning to go direct thread. I have been trying to convince him to get a tri lug. Direct thread always presents the problem of the silencer working loose. I have used mine on a Glock 45 and it is frequently a bit loose after 3 or 4 mags. Very concerning.

Tri lug is super fast, foolproof, and absolutely locked on the gun.

I don't see myself using it on the glock very much. But it came with the booster so I went ahead and got a silencerco barrel for the glock. It's quiet and neat. But the Obsidian will be on the CMMG 60-70% of the time and on a Ruger Precision Rimfire 22 the rest of the time. It is very effective on a 22lr but at the expense of being heavier than a dedicated 22lr can. This rifle is on a bipod, bags or a tripod all the time so the weight isn't a detriment. 22lr is very dirty so the user serviceability of the Obsidian is a big plus. The baffles snap together VERY tightly. I use a hard plastic chamber flag as a lever to pop them apart for cleaning. You aren't going to take them apart by hand.

quote:

Originally posted by KSGM:
In regards to that Innovative Arms Scorpion upper: I don't know how sensible it is to shoot lighter bullets slower.

Yeah, the draw for me isn't that I should, but merely that I could if need be. I also don't know how sensible it is to spend two or three times the coin on a suppressor I can't remove from the gun, but on paper it sounds great.

Growing up, I also had a fascination with the MP5SD variants, and this is like a modern take on that.

quote:

Originally posted by KSGM:
I believe the MP5SD ran into problems, if you did shoot subs through it; is that Scorpion similarly afflicted?

The video reviews I watched seemed to indicate it would eat everything without complaint. With 147gr and 150gr ammo, it is ridiculously quiet.

quote:

Originally posted by KSGM:
I will not deny that I have a little "fan boy" in me, when it comes to the MP5; same with the P90. I own neither though, because I ultimately can't logically justify such an expenditure at this time.

Yeah, when Washington passed I forget which piece of horrible legislature back in 2018 or 2019 that created an "assault weapon" registry of anything semi-auto, I splurged and got a P90. I had always wanted one, and it was a "now or ask permission" situation so I bought one, a whole pile of magazines when they were still $15 a pop, and just put it all away. That gun makes little sense, and is fully a "you had to be there" generational thing, I think. I also need to paper that one because as little sense as it makes to own, it makes even less with the 16" barrel. 10.3" and a can, please, which brings us back to suppressors that can be removed and attached to other stuff.

quote:

Originally posted by IndianaBoy:
100% get the tri-lug.

A buddy of mine with an MP5 is waiting on stamp approval of a Dead Air Wolfman and he is planning to go direct thread. I have been trying to convince him to get a tri lug. Direct thread always presents the problem of the silencer working loose. I have used mine on a Glock 45 and it is frequently a bit loose after 3 or 4 mags. Very concerning.

Tri lug is super fast, foolproof, and absolutely locked on the gun.

Yeah, I went deep down the suppressor rabbit hole last night on YouTube after replying to this thread. What struck me with the one channel I spent a lot of time with was the guy had a habit of gingerly checking that the suppressor was firmly threaded onto whatever pistol he was shooting, which seemed reasonable the first few times I saw him do it. But he did it every three of four shots, consistently. That told me a lot. So yes, tri lug seems like a no-brainer for me. If I can easily unthread the tri lug to install whatever adapter and booster I need for pistols, I don't know why I wouldn't do that. What is his reasoning for going direct thread? Or is it just pure inexperience?

Direct thread will typically save some length and weight; though it's probably more meaningful/pronounced in center-fire rifle silencers, than pistol cans. Depending on the host, a strap wrench and nylon thread tape will ensure things don't come loose. A lot of DT cans have flats, or a some other surface for a proprietary tool to engage, to facilitate more robust tightening. I have used a Gemtech Trek a lot, on multiple AR15s; I have never had it loosen up.

Tri-lug is super cool. I don't have a gun that uses it, but I have played with it. Not only is it apparently fool-proof, as Indianaboy says, it is just damn cool to take the silencer on and off. If I had one, I'd wear it out, just by needlessly playing with it.