CMMG Radial Delayed 9 mm - First trips

[tekmann2377]

I have always wanted a 9 mm upper or 9 mm subgun for range plinking. I was never the biggest fan of straight blowback uppers for multiple reasons, most namely they are loud, and they tend to have a higher recoil impulse than locked breech systems. I also didn't want to deal with a mag well adapter or dedicated lower.

Anyways Midway had a sale on CMMG radial delayed uppers several months ago, and I picked up a 5" complete Banshee upper. I finally got around to shooting it.

In short, it runs great. Digested 115 and 147 hr loads without issue. The CMMG magazine that goes in a standard AR magwell worked without a hitch, and the BHO worked too. It suppressed reasonably well with a Primal 46.

I used it on a standard AR lower with a Geiselle SD3G trigger and standard carbine buffer. There were no trigger issues either.

I didn't shoot it enough to conclusively establish it's reliability but so far it has been off to a solid start.

 

[mattc51]

New fixed ejector or old style spring ejector on the bolt? Reliability will be effected if it is the old spring ejector.

 

[Sheldon N]

I've always been interested in getting one of these as a fun range toy.

Have you followed the articles/recommendations for upgrading the buffer setup to smooth out the recoil impulse? The go-to recipe seems to be an A5 length buffer tube, a Tubb flat wire 308 spring, and a Kynshot RB5007 hydraulic buffer.

 

[tekmann2377]

To be honest I don't know what kind of ejector it is. The ejection pattern is 4 o'clock and very brisk, and there did not appear to be any issues with weak or inconsistent ejection between different ammo either.

I am not bothering to do anything with the buffer, spring, or buffer tube. This pistol lower is shared with a 12.5" 5.56 upper as well and I don't want to induce any reliability issues with that. I don't shoot subgun or pistol enough to bother with optimizing the setup if it runs fine.

 

[mattc51]

Keep track of round count. The spring ejector AR bolt style have a life span of about 300-500 rounds before ejection goes down the toilet. The spring tunnel for the ejector will be full of gunk and the spring will be too short to eject the shell. They will send an extra strong spring and it will do the same after the same round count.

 

[TonyAngel]

I have always wanted a 9 mm upper or 9 mm subgun for range plinking. I was never the biggest fan of straight blowback uppers for multiple reasons, most namely they are loud, and they tend to have a higher recoil impulse than locked breech systems. I also didn't want to deal with a mag well adapter or dedicated lower.

Anyways Midway had a sale on CMMG radial delayed uppers several months ago, and I picked up a 5" complete Banshee upper. I finally got around to shooting it.

In short, it runs great. Digested 115 and 147 hr loads without issue. The CMMG magazine that goes in a standard AR magwell worked without a hitch, and the BHO worked too. It suppressed reasonably well with a Primal 46.

I used it on a standard AR lower with a Geiselle SD3G trigger and standard carbine buffer. There were no trigger issues either.

I didn't shoot it enough to conclusively establish it's reliability but so far it has been off to a solid start.

Keep track of round count. The spring ejector AR bolt style have a life span of about 300-500 rounds before ejection goes down the toilet. The spring tunnel for the ejector will be full of gunk and the spring will be too short to eject the shell. They will send an extra strong spring and it will do the same after the same round count.

Yeah, you're going to want to determine which version you have. Fixed or spring loaded ejector. I had the spring loaded ejector version and, although my original ejector spring lasted a lot longer than most, it did give out at some point. Since replacing it, it now requires replacement every 800 rounds or so. The springs are pretty cheap, but it makes you question reliability for any use other than just being a range toy.

My intended use is as a house gun, so I upgraded to the fixed ejector.

The upgrade, which included a bolt carrier group and upper receiver, was over $300 and I was hesitant to give CMMG more money after getting screwed on the spring ejector version, but there is no other PCC that met my requirements.

 

[N_Turs]

Mean arms is another builder of a bearing delayed upper. They are built more for pcc comps but its been a super reliable platform and in a shorter version would be great for a hd weapon. I have a 14.5 I shoot in PCSL matches and have over 1500 on it now with just minor cleaning and oiling. Haven't had a single issue with it at all. They also have different lifters that can be swapped to tune it like an mp5 with the locking piece and rollers.

 

[TonyAngel]

Mean arms is another builder of a bearing delayed upper. They are built more for pcc comps but its been a super reliable platform and in a shorter version would be great for a hd weapon. I have a 14.5 I shoot in PCSL matches and have over 1500 on it now with just minor cleaning and oiling. Haven't had a single issue with it at all. They also have different lifters that can be swapped to tune it like an mp5 with the locking piece and rollers.

Yeah, the mean arms is nice, but man .... that price tag. Not counting the cost of the parts I already had on hand, I still have less than $800 in my radial delayed blowback rig.

What I was wondering about the meaning arms is whether you need to do anything before running suppressed? Like changing some part to alter closed bolt lock time.

 

[ddavis]

Good to know about the potential issues with the spring ejector. My CMMG set up has prob 2k rounds on it without a single failure so far using the Endo/Mean mags. If I start to have ejection issues I'll replace that spring. I have an A5 buffer and at one point put a super heavy buffer in it and there was a noticeable delay of the initial recoil and then the forward recoil when the bolt hit home. The system moved so slow. With a regular weight buffer it still cycles pretty slow but it's closer to one motion now. Very soft. Fun when it's super safe.

 

[redbullitt]

Definitely love the newer fixed ejection model. A flat wire spring and hydraulic buffer is awesome, super flat shooting.

 

[Ape_Factory]

I dove in to the PCC world here recently myself, CMMG radial delayed with the ejector in the bolt. I bought a set of Tubb springs for the ejector and extractor if/when the stock ones go south. Didn't know about the potential issues until after I purchased everything. With that said, I've had major issues elsewhere, first with finding the right spring/buffer combo and now a feed issue. But I have a pretty complicated setup, a Broad River Tactical upper, SD/Suppressed (like the MP5 SD) and an FRT. Using Mean Exomags but just ordered an Endomag to convert a standard AR15 mag to 9mm to see if it'll solve the feeding issue.

Running a Sprinco yellow with a 3oz. buffer per Broad River's recommendation and dropping the bolt from locked back will produce the failure to feed about 1/3 to 1/2 of the time with round nose FMJ's or . Given the fact I can induce the FTF from just dropping the bolt, it has to be a mag issue, either the mag itself or possibly the height of the inserted mag.

It's running off of a ADM lower. Not sure how I can adjust the seating depth of the mag and I'm not sure if it's too high or too low. As such, I'm a bit afraid to start filing away at the mags or the mag catch.

It's so damn amazingly quiet that I must get this thing running. I've even developed supersonic 147 grain rounds. If you're unfamiliar with an SD system, it has a set of radial bleed ports just aft of the chamber which bleed off energy from a supersonic round into a big titanium chamber, then through a suppressor and make it subsonic. It'll run 115 or 124 supers and turn them into subs, exiting at about 1050 to 1080, chrono measured.

I am going to try a slightly lighter buffer but I'm pretty convinced it's a mag issue. A heavier buffer yielded two successful shots followed by it not picking up the next round. The first time I ran it with the new spring and 3oz. buffer, it ran fine. Second outing, I started getting the FTF's. Less than 100 rounds through it. Bizarre.

 

[TonyAngel]

I dove in to the PCC world here recently myself, CMMG radial delayed with the ejector in the bolt. I bought a set of Tubb springs for the ejector and extractor if/when the stock ones go south. Didn't know about the potential issues until after I purchased everything. With that said, I've had major issues elsewhere, first with finding the right spring/buffer combo and now a feed issue. But I have a pretty complicated setup, a Broad River Tactical upper, SD/Suppressed (like the MP5 SD) and an FRT. Using Mean Exomags but just ordered an Endomag to convert a standard AR15 mag to 9mm to see if it'll solve the feeding issue.

Running a Sprinco yellow with a 3oz. buffer per Broad River's recommendation and dropping the bolt from locked back will produce the failure to feed about 1/3 to 1/2 of the time with round nose FMJ's or . Given the fact I can induce the FTF from just dropping the bolt, it has to be a mag issue, either the mag itself or possibly the height of the inserted mag.

It's running off of a ADM lower. Not sure how I can adjust the seating depth of the mag and I'm not sure if it's too high or too low. As such, I'm a bit afraid to start filing away at the mags or the mag catch.

It's so damn amazingly quiet that I must get this thing running. I've even developed supersonic 147 grain rounds. If you're unfamiliar with an SD system, it has a set of radial bleed ports just aft of the chamber which bleed off energy from a supersonic round into a big titanium chamber, then through a suppressor and make it subsonic. It'll run 115 or 124 supers and turn them into subs, exiting at about 1050 to 1080, chrono measured.

I am going to try a slightly lighter buffer but I'm pretty convinced it's a mag issue. A heavier buffer yielded two successful shots followed by it not picking up the next round. The first time I ran it with the new spring and 3oz. buffer, it ran fine. Second outing, I started getting the FTF's. Less than 100 rounds through it. Bizarre.

View attachment 8788660

I've tried everything from the tubbs to inconel ejector springs and I had the best luck with CMMG Mk10 springs.

Just looking at that pic, I can't tell where the round is hung up. What happens when you push on the bolt when it's in that state?

I get it that the yellow spring was recommended, but that's a really light spring. If it ran good when the spring was brand new, maybe try a standard buffer spring. I wouldn't go removing any material from anything until you tried the simple stuff first.

Just out of curiosity, why would you want a rig like that? Can you shoot and cycle subs with it or are you limited to supersonic ammo?

 

[Ape_Factory]

Good to know on the Mk10 springs. I was actually up in Columbia, MO prior to receiving this upper and was going to drive over and purchase a bag full of springs from CMMG (somewhat kidding). I wasn't aware of the ejector issues prior to the purchase of the upper and I should have done more research prior to hitting the "buy now" button. 20/20 hindsight, I would have bought the barrel, hand guard and SD adapter from Broad River and then gotten the CMMG external ejector upper/BCG from CMMG. CMMG won't deal on the external ejector setups so BR's still using the bolt face ejector setup. But for now, that's the least of my problems.

If you push forward on the bolt, the BCG and the bullet doesn't go anywhere. It's basically jamming at the very top of the upper receiver prior to entering the extension. It doesn't do this every time, it's very inconsistent. I might get three or even five rounds in a row where it works and the sixth will FTF or I might get one round before another FTF. No rhyme or reason. All in normal semi-auto mode.

I'm hoping I can get back to the range this weekend and try out different buffer weights and springs. I'd think if it were the spring or buffer, I wouldnt' get a failure to feed by dropping the bolt. Maybe it's not moving fast enough and the bullet is jumping or springing up once it's free of the feed lips? I do get serious bullet set back so each round that gets jammed like that gets thrown into the pull pile. I have a mil-spec trigger in there now but I may try going back to say a Geissele SSA without the super safety. I've tried full and not full mags. I have five of them, same result and the endomag conversion on the way.

Yes, you can shoot and cycle subs with it as well. Looking at the data, it removes about 100fps from the bullet's velocity. It's a 5" barrel. I've already started my load development with NAS3 cases and running supersonic 147 grain pills and have a solid load using BE-86 and I'm working on another load with Vihtavouri N350 which was too slow my last outing but super clean burning. Both are very low flash but the Alliant seems to have a bit more gas to cycle the action at a lower charge weight. But even with standard NATO 124 grain cartridges, FMJ, it'll still get feed errors just as consistently as any other round. I may try shooting some slow motion video.

As to why, well it's really really quiet with no recoil even at FRT speeds using a flow through suppressor. Like half the volume, seemingly, of my 300 Blackout gas gun with a 9" barrel and optimized 300 Blackout suppressor shooting subs. The recoil impulse is minimal in comparison so I think my wife will like shooting it more. And it's a whole lot less expensive to shoot (especially in FRT mode!).

I did check the bolt face for rough edges and found nothing that cases may get hung up on while sliding onto the bolt face.

The other variable I'm considering is that it needs a higher back pressure can to cycle. I currently use a Hux Flow 9Ti. The SD adapter is a HUB mount version so it won't work with my high back pressure 9mm can. I have a 3oz buffer in there now but I have an adjustable Odin buffer and can go lower in weight. I have enough different springs to try a bunch of stuff. I will say it didn't run with either version of the Unrivaled dead blow captured buffer system OR the JP SCS either, with the latter likely having too much buffer weight. I'd get two rounds and then it would not cycle and pick up the next round on all three of those captured buffer systems.

I'll solve it. I know they run, there are a bunch of these out there that are all working just fine so there's something with my combo that's just not allowing it to function like it should.

 

[hlee]

If you push forward on the bolt, the BCG and the bullet doesn't go anywhere. It's basically jamming at the very top of the upper receiver prior to entering the extension. It doesn't do this every time, it's very inconsistent. I might get three or even five rounds in a row where it works and the sixth will FTF or I might get one round before another FTF. No rhyme or reason. All in normal semi-auto mode.

Somewhat off topic… have this EXACT same FTF on a Tisas 2011. I assume it’s a mag issue, but I haven’t yet identified which in my collection causes the issue. Too inconsistent. It will run run 5 mags straight without a hiccup before a match, then FTF every mag during a match. Anyway, I’m going to start by marking mags that FTF and see if I can find some correlation.

 

[Ape_Factory]

You're using the Checkmate mags too, correct? I have it's cousin, the MAC 9DS comp and it's been 100% reliable but I'm not shooting matches with it so you've probably run 10X the ammo I have through mine. I also went with +3 extensions which did NOT come with a new spring which I thought was odd but thus far, they work.