New CMMG Upper... Much Better!!

[thunderbolt]

Last week I purchased a complete CMMG .22 upper w/ a phosphated bolt for my AR rifle along with three 10 rnd mags. After a good cleaning and buffing I took it out to the range this week but was frustrated by its performance. I wrestled through almost 400 rnds using three different brands of ammo. On average it would fail to fire at least 3 rnds out of the 10, regardless of magazine, and would almost always fail to extract that round. Once I did extract the round I could see that the firing pin had struck it. It would also stove pipe fairly regularly as well as failing to eject a spent round causing a jam. On a couple of occasions the spent shell would get lodged above the bolt against the charging handle and a complete disassembly was required. It never did fire a complete mag without some problem.

I have read that these uppers may require a "break-in period" and I was wondering if this kind of operation is normal. I gave it a super cleaning after I got back and I was planning to take it out again to see if I could get it to run smoother but I haven't had the chance. I'm actually kinda pissed about this. I expected some rough operation until I broke it in but this is ridiculous. Any help?

[97F1504RAD]

What kind of ammo are you using?

I would use nothing but CCI Mini Mags for break in and then after that see how things go.

[NorCalDustin]

1) The breakin period is the first 200rnds minimum..

2) What kind of ammo are you using?


I have one with the Stainless Steel bolt/Barrel Collar, Forward Assist Adapter, and Bolt Hold Open... I've put over THOUSANDS of rounds through it in the last 3-4 months... When using quality ammo, I only ever had 3 malfunctions. When using Remington GB's (CMMG DOES NOT recommend you run GB's) I get the occasional FTF (Bad round)...

Mine eat's everything.

[NorCalDustin]

Also do you have a notched hammer?

[thunderbolt]

I was using CCI mini mags (only had 50 of em though), Federal bulk 36gr HP copper and some 40gr lead "match grade" stuff that I can't seem to remember the brand right now (comes in a tan 350 rnd box). I never use Remington ammo...

My hammer is NOT notched.

This is gonna sound like a stupid question but if the break-in period is 200 rnds have I blown it?

I sold off my GSG-5 which ate everything for this and now I'm...grrr.

EDIT: The other ammo is Federal Target Grade 40gr lead.

[Carsgunsandchics]

How about kicking back in front of the tv and hand cycling the bold a few hundred times? It sounds like everything is still real tight and with new coatings in the wear areas causing binding. Throw some oil in it where the bolt rides and cycle the bejeeses till it marks its wear pattern, once you get that it will start to feel smoother.
On mine the phosphate finish on the rails was causing major problems, and once the wear pattern ate thru it, I have not had a single problem.

[NorCalDustin]

I was using CCI mini mags (only had 50 of em though), Federal bulk 36gr HP copper and some 40gr lead "match grade" stuff that I can't seem to remember the brand right now (comes in a tan 350 rnd box). I never use Remington ammo...

As far as I know my hammer isn't notched but I'll check again when I get home.

This is gonna sound like a stupid question but if the break-in period is 200 rnds have I blown it?

I sold off my GSG-5 which ate everything for this and now I'm...grrr.

Probably... I would contact CMMG... IIRC, Dude's name is Taz... He's a wiz with these upper's... They WILL take care of you.

It sounds like to me though that it just needs more break-in.

[shadow65]

This is certainly not normal. I do know a few bad extractors got through. I've only ran across two, and as luck would have it, I have one. Better me than a customer.

Some minor break in with the parkerized kits is necessary but you should not be having those problems. These kits are made to run out of the box. Plug and play.
Did you take it apart? I ask because if you do not have experience taking it apart, the rails can get out of spec, which will cause cycling problems.

Another thing to do is buzz the chamber.
Use a bronze .22 bore brush in a couple sections of G.I. cleaning rod. Chuck it in a drill. Put some oil on the brush and run it in and out of the chamber until warm. This gets the crud out and smooths the chamber.

If you continue to have problems, IM me or call CMMG. We will get you running.
Sorry for the problems.
Dave

[thunderbolt]

Did you take it apart? I ask because if you do not have experience taking it apart, the rails can get out of spec, which will cause cycling problems.

The farthest I took the bolt apart was removing the firing pin and cleaning the channel. Is it normal that the firing pin hits the round at an angle?

[shadow65]

What do you mean at an angle?
Are the rounds sticking in the chamber?
Dave

[thunderbolt]

The way the firing pin sits in the channel (with the groove that the retaining pin fits in I'm assuming that's how it sits in there) causes the firing pin to strike the round at an almost 40 degree angle. Basicly it's not squared with the bolt face. If it's suppose to be square I haven't found a way to make it so.

If I cycle a mag without firing none of the rounds stick but I've had to pry many rounds out with a small screwdriver (no damage to the rifle).

I'm headed to the range to try some different ammo and to see if I can get it to run.

[Arteel]

If you still can't get it figured out, let me know. I'd be more than happy to meet you at the range to see whats wrong with it. I've been through two of these uppers which both displayed similar issues you are having. I managed to get them working perfectly after some tweaking. If you haven't already, pick up some lightened hammer and trigger springs from JP.

[shadow65]

It's a great jesture for you to offer a hand getting him running. Good to see in the Firearms Community.

Again guys, there should be no lasting issues with these kits after break in.
I use my uppers and kits with no changes to the lowers.
I use my same lowers for 5.56.
That is what they were designed to do.

JP springs will make the trigger lighter but should not be needed for the kit to work. If they do, then there is friction some where slowing the cycling down.

We will be sending a call tag to thunderbolt and replacing the kit.


Dave

[Arteel]

It's a great jesture for you to offer a hand getting him running. Good to see in the Firearms Community.

I'm just trying to return the many hands I've been offered on here!

Again guys, there should be no lasting issues with these kits after break in.
I use my uppers and kits with no changes to the lowers.
I use my same lowers for 5.56.
That is what they were designed to do.

JP springs will make the trigger lighter but should not be needed for the kit to work. If they do, then there is friction some where slowing the cycling down.

We will be sending a call tag to thunderbolt and replacing the kit.

Dave

Very cool of you guys. Looks like he's in good hands.

[thunderbolt]

Got my upper back last night but wouldn't you know it's pouring rain. The frustration continues...

But the upper looks good. I had them upgrade the bolt and collar to stainless steel so we'll see how it runs. I have high hopes. Maybe I'll go out after all...