CMMG WASP dedicated .22 upper issues

[djleisure]

I recently traded a fellow Calgunner for this dedicated CMMG upper (basically new) and finally had a chance to take it out last weekend. Well, in a nutshell, it was TERRIBLE. I followed the very basic "troubleshooting" guide on CMMG's website, which basically means I oiled a few spots before shooting it. I only tried running a few mags through it before getting too frustrated to deal with it. By the way, this is on a lower with a rounded, DPMS-style hammer.

It couldn't make it through a single mag without non-firing light-strikes which I then could not extract without a knife (I know you can't hand cycle most .22's, but still this was annoying.) I'd say four out of ten shots on the first two mags did this. This was using Federal Bulk.

Thinking my problem might be the Federal Bulk I switched to some much higher end, "match grade" .22 ammo (it's slipping my mind right now, but something by Remington.) It would NOT even load a round into the chamber. It was like the round was too fat to go in the chamber OR the recoil spring did not have enough power to push the round in the chamber (or both!)

I have heard that some dedicated .22 uppers take some break-in time, but neither of these issues seem like a "break-in issue." I would cycle just fine when it actually loaded AND fired the round. I tried checking around here and ARF (and CMMG's website) but can't find anyone with similar issues. Anyone have any thoughts? Oh, I was using BDM 10/30's, but that doesn't really seem to matter here.

[sephy]

Wow I'm sorry. I know with my CMMG if I get a light strike I just drop the mag, pull the charge handle, and try again. I haven't had one not fire at all. When a round does get stuck in the chamber (subsonics mostly), if I just pull the handle a few times it flies out. I shot CCI standard and mini mag 100 rounds each and 400 rounds of SK standard in a weekend while camping without cleaning or oiling and it ran fine... I'd think about sending it in for repair. Then again, a new set of springs is $11 so you could try that too.

[dchang0]

OUCH.

If you were using Remington Golden Bullets, the fault is with the ammo and not the rifle. Golden Bullets are slightly larger than spec and have softer-than-usual brass cases AND have prominent driving bands that blunt easily upon feeding and fatten the bullet too much for the chamber. I had 100% failures to feed with them UNTIL I used a Dremel and file to polish the feedramp and widen the chamber mouth on my dedicated Spikes.

So that leads me to believe that you have a smaller than usual chamber. You should be able to hand-feed AND hand-extract (with a fingernail, not a knife) Federal bulk easily. And the light strikes idea supports this hypothesis: if your ammo isn't feeding all the way in but is pretty close, the hammer striking the bolt will finish driving the ammo into the chamber but won't have enough momentum left to drive the firing pin firmly into the rim.

So, I say you need to send that sucker back to CMMG under warranty to have them redo the feedramp and edges of the chamber.

[djleisure]

Thanks, dchang0! That is some very good info! I'll check the specific ammo when I get home, but Remington Golden Bullet actually sounds right! I do have a Dremel and if I have no other recourse, I will certainly go to town on the feedramp and chamber. BUT first I think I'll try contacting CMMG and see if I can send it back to them for a little TLC.

[djleisure]

Wow I'm sorry. I know with my CMMG if I get a light strike I just drop the mag, pull the charge handle, and try again. I haven't had one not fire at all. When a round does get stuck in the chamber (subsonics mostly), if I just pull the handle a few times it flies out. I shot CCI standard and mini mag 100 rounds each and 400 rounds of SK standard in a weekend while camping without cleaning or oiling and it ran fine... I'd think about sending it in for repair. Then again, a new set of springs is $11 so you could try that too.

Glad yours is working out for you, sephy! I hope I can get mine more reliable soon...

[Arteel]

Mine needed quite bit of tuning to run reliably. I had to cut about 9 coils off the recoil spring and dremeled the lip on the feedramp that the bullets kept getting caught on resulting in feeding problems.

Nevertheless, I did manage to get the upper to run flawlessly.

[dchang0]

Thanks, dchang0! That is some very good info! I'll check the specific ammo when I get home, but Remington Golden Bullet actually sounds right! I do have a Dremel and if I have no other recourse, I will certainly go to town on the feedramp and chamber. BUT first I think I'll try contacting CMMG and see if I can send it back to them for a little TLC.

Glad to help!

If you do decide to do it yourself...

Check the Spikes tuning guide at AR15.com. There is an excellent write-up with pictures on exactly how to use a Dremel to clean up your feedramps and chamber.

http://www.ar15.com/forums/topic.html?b=2&f=282&t=173040

BTW, I used Flitz metal polish which is much finer than jeweler's rouge and works great for this purpose. I didn't have to take the barrel out of the upper receiver either--just use the Dremel felt cone fully extended out of the chuck and it'll work fine. If you want to polish the inside of the chamber, a Q-tip with plastic shaft will work at flexing slightly to get inside the chamber.

Now, I can feed Golden Bullets 99% of the time, even re-feeding damaged/fattened rounds. I still have trouble when the chamber/ramp starts getting dirty, though, as Golden Bullets are very, very dirty ammo. But that's what spray gun-scrubber is for (not CLP, just the scrubber without lube)!

Also, try not to cut your recoil spring as that is a fix for stovepiping. A strong recoil spring helps with feeding problems. I cut only 1/4" off my recoil spring and went with the reduced-power hammer spring to reduce stovepiping.

[jrr]

Ok, is your upper the "old" model or the new one? The difference is that the new ones have a setscrew in the bolt carrier collar that screws into a machined groove on the barrel extension. If you have the new one make sure you are tightened down. I suspect they made that change because without the set screw the whole bolt group can be pushed away from the barrel when chambering a round causing an out of battery firing.

The reason I know this is that i had an old model, and being a DIY guy (AKA "Bubba" ) I thought I would ramp the barrel and smooth out the chamber on my original upper. I also thought I could fix the lack of extraction of unfired rounds. Well, after doing my work with the dremel I took it to the range. Managed to get one round to feed, which promptly ruptured upon firing because I had removed just a bit too much and the case wasn't evenly and adequately supported. Fortunately .22lr isnt that powerful and the bolt carrier collar, bolt, and barrel extension are super tough solid steel, so the rupture didnt do any damage, but it looked nasty and put the fear o' God in me.

So, I wrote off that barrel, ordered a new one and a new style bolt collar to go with it. Fitted that, and runs like a champ. BUT I still notice two things.. one is that the cases bulge at the rear if you don't lock the set screw. Most likely due to being slightly out of battery. Two, some ammo just will not work. I have Aguila, Remington gold bulk, and CCi stingers and match. The match will not feed at all, The bullet is just slightly longer than the others and will hang on the chamber walls.

So, my hard won advice is don't take a dremel to it to do anything more than a fluff and buff and buzz the chamber, and try different ammo to see what works and what doesn't. And if you have the later model upper, use the setscrew. If not, consider the $30 new style collar with the setscrew, it should still work even without the machined groove in the barrel. Having the whole thing snugged up tight takes any back and forth play out, so if your bolt were out of battery it should fix that. An out of battery bolt could cause not only bulged cases, but also could cause light strikes because the case head is too far away from the bolt, or maybe even from the round moving slightly forward when struck. And like the other poster said, when it does happen try removing the mag, rack the bolt, and hit it again.
Cheers!

[djleisure]

Some more great info! Thanks jrr, dchang0(again!) and Arteeel - this gives me a lot to work with and a little hope for a functioning dedicated upper!