CMMG Radial Delayed 9 mm - First trips

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

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.

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.

tekmann2377 said:

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.

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mattc51 said:

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.

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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.

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.

N_Turs said:

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.

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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.

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.

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

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.