My 8" CMMG Guard has been suffering failure to eject issues. I first ran about 100 rds through it without a single issue. Then it started jamming every round or two. I tried different ammo, different magazines, cleaning it, etc. I contacted the company and was sent a new ejector spring and buffer tube spring to try to fix the issue. I took it back to the range and it was still jamming. I contacted them again and they had me send the Guard back to them with the magazines that I was using. I did so and they had it a couple of weeks. They sent me a video of them rapid firing a hi-cap mag. I told them that it looked good to me and they sent it back to me. After they sent me the video of them fast-firing the pistol without issue, I asked them what they'd done to it and they replied that their techs had to do some machining or something to that effect. No specifics there. I took it to the range a few days ago and fired about 50 rounds through it without a single failure. Its accuracy with regular FMJ was frankly quite surprising (a half dollar-sized hole at about 10 yards). I was feeling VERY confident in it as a defensive weapon (the sole reason that I chose to purchase it), almost "giddy". I was able to slow fire, fire in 2-round bursts, or rapid fire in strings of up to 10 rounds or so.

But around the 50 round mark I heard that familiar "click" sound and checked the chamber. Sure enough... there were 3 rounds jammed in the open bolt area (one spent, one unfired, and one in the chamber). I cleared the malfunction and fired again. Within a round or two it had jammed again. Over the next 30-60 minutes I tried all kinds of remedies. I very liberally lubed the bolt with CLP. I tried three different mags two 30 round Glock mags and a 20 round non-Glock branded mag), three different FMJ ammo brands and anything else that I could think of. Including holding the magazine in very tightly as I fired it, loading the magazines with anywhere from 1 to 30 rounds. When I just loaded a single round into the mags it would always fire that round and fully eject it, with the hold-open function engaging in all but one instance. In that case, the magazine dropped-free without my pressing the magazine release. I chalked that up to an aberration or me not fully inserting it. The FTEs usually consisted of a loaded round in the chamber, a spent round at a 45 degree angle in the open bolt area, and a loaded round in between the magazine and chamber. When I would clear the malfunction, the round in the chamber was always loose and able to drop-free, so it wasn't an issue with the round being jammed in the chamber. My gut feeling is that the timing is wrong, since I often found those three different rounds in the open-bolt area after an FTF. Seems like the extraction/ejection timing just is off.

I bought this firearm upon the recommendation of a coworker and friend who is a long time member of the local SWAT team. I had been looking seriously at the Sig MCX/MPX platform, as well as the Springfield Saint pistol. But my friend's recommendation swung me to the CMMG brand (which I was unfamiliar with). And the staff at the retailer of all three brands  seemed to think highly of the CMMG as well. At this point I am just unsure what is causing this issue. I have lost confidence in the ability of this firearm to reliably function, which is of course paramount in a defensive firearm. I've got two other ARs that function well, but considering all that is going on in the world right now, I am feeling quite unsettled about this purchase at the moment. Considering the ease of which this firearm is to operate and the accuracy that I have seen... all of that could be rectified if I could just get a reliable example of this model. I would SO much rather use this in a CQB situation than my full-size 5.56 or M-4gery... or one of my .308 thumpers.

Any ideas at all of things that I can try here? I haven't heard back from the company yet and suspect that they are on lock-down right now because of COVID19.

UPDATE... Bryan from tech support contacted me today. He's always been very helpful and communicative before. He said they'd updated their extractor springs and ejector assembly since mine shipped, and that they'll be shipping the updated ones on Thursday or Friday. Awesome! Will update when they arrive and I install and back out to range test. I really wanna pick up where I left off with this thing regarding the awesome accuracy and pleasure to shoot.

looking forward to hearing how she's running

Got the extractor assembly and two ejector springs today. Installed new parts. I plan to get to the range within the next week or so. Would head out there tomorrow sometime, only it rained and snowed pretty heavily all day today, and supposed to snow most of the week. Gonna be a mucky mess. Will get out there as soon as I can, and give a range report here. Will also be updating Bryan at CMMG as well. Hoping to give him great news!

https://www.ar15.com/forums/AR-15/Rimfire-and-Pistol-Calibers/15/

Several threads on this very issue in the rimfire/pistol caliber area.  @amphibian has extensively tested this issue out on several different bolts/barrels/calibers and has come to the conclusion that headspacing issues are likely the prime candidate for the failure.

You might want to dig around in that subforum and take a look at some of the threads he and others including myself have made on this very issue. Hopefully the parts Bryan sent you work out.  I haven't had a chance to get out and test the replacement springs they sent me yet either.  Best of luck with this.

@ jeremywills

Thanks for the response. I'll look into your suggestions.

Meant to update this thread over the weekend, but got busy with a bunch of work issues.

I received the ejector and extractor parts and installed them last Wednesday, and was able to get out to the range for a quick trip on Friday. Ran about 100 rounds of 124gr FMJ through it without any issues at all. I did try some JHPs and those experienced consistent failure-to-feeds, but that doesn't concern me particularly at this point. I may try some different JHPs (such as Hornady Critical Defense) and see if those will feed. But I understand that getting JHPs to feed reliably can be tricky with some firearms. Overall I am happy with the Guard and hope/plan to use it with confidence after I've tested it a few more times. Sure is a pleasure to shoot and comfortable to carry and hold.

I bought a Banshee 200 in 45acp with 8" barrel.
After approximately 300 rounds of both jacketed HP and std ball (both 230 grains), I realized I can run 100% no FTE/FTF ball, and about 30-50% with the HP.
Very disappointing, but I haven't had time to experiment with other rounds to see what else I can reliably feed it.

This pistol is nice, just my first time with a firearm that doesn't reliably eat anything I feed it.

Red_Label, Have you been reading any of Amphibian's posts about the experiments he's been doing. Going with an A5 length buffer tube, Kynshot buffer and Tubbs flat wire spring really enhances the smoothness of the CMMG RDB setup.

Has CMMG acknowledged badly head spaced barrels? Have they replaced any or does it look like we just gotta stick with em?

That buffer/tube/spring combo really does smooth out the operation of the 9mm RDB bolt and barrel.  It also as a side bonus works great to smooth out a 5.56 upper and bolt.  I'm considering buying a few more and setting up all of my lowers the same.

I've only had a chance to put a couple hundred rounds on the replacement ejector spring.  So far so good.  If I get to the 1k mark without issue I'll consider it resolved.  With the original spring I barely made it to 500 rounds before it became a jam o matic.  We shall see.

No, but I will. Thanks for the heads-up.

I've been swamped lately between working from home, and deciding to reload 3K of .308, 5K of 9mm, and 3K of .45acp brass that I've had laying around for 10 years. I have two single stage presses, so as you can imagine... it's grueling and will take a while.

The second time that I'd had the issue (after they'd had me replace the buffer tube spring and ejector spring), I sent it back to them and asked what they ended up doing to it, and was told "some machining and refinishing". Shrugged my shoulders and accepted the explanation. But it was still a jam-o-matic until I replaced the extractor and ejector springs again. Hopefully it will continue to run reliably.

Been following the CMMG RBD posts with great interest, really looking to buy one. It would seem that CMMG has a problem with the RBD design that they don't want to address, seemingly producing and selling guns that they hope are in working order while folks seem to keep having the same problem. Also seems folks are getting the run around from CMMG!

Well I've had excellent customer service from them. But yeah... I spent about $1500 on my Guard and several hundred more for 30rd Glock mags and ammo and gas for the range trips... so yeah, it would be damn nice if I had a reliable gun out of the box. The vast majority of my firearms have been 100% reliable out of the box, including several examples each of various Taurus and Kahr models that were far less expensive. In fact, the only firearms that I've had that were less reliable were my Llama Mini Max and my S&W M&P 15-22. The Llama got dumped and the S&W got sent back to S&W for service and has been 100% reliable for thousands of rounds since.

My large chain local retailer keeps selling the CMMG ARs in the year and a half since I first got mine and started experiencing issues. So I can't imagine that every one is a jam-o-matic. And the part that confuses me is why would the first 100rds be flawless, and then every round after that jam? And then after it got sent back for service, it ran about two mags fine before starting to jam every round? It just doesn't make sense unless the springs are made with poor quality steel, or are overstressed and wear-out incredibly fast. Anyways... I'll check the threads out mentioned here and keep testing and hoping it'll stay reliable. I should probably pick up spare springs. They did send me two ejector springs, which makes sense because failures to eject have been my problem thus far, until the last hundred rounds.