CMMG .22 upper problems with light strikes

[kokopelli]

ok...some time ago I complained about the Remington SubSonics not being worth a poo in this thing-
it's a full CMMG .22 dedicated upper assembly. It's on my Zombie Defense lower that has a DoubleStar LPK in it.
The Remington SS would not cycle more than 2 rounds at a time -firing with a crap Thompson Machine suppressor. I have to shoot SS through this piece of crap suppressor because it is a piece of garbage that is not hearing safe with full velocity loads.

The consensus was that the Rem. SS's were not giving enough 'umph' to knock the hammer back all the way.

Today I tried Federal bulk pack .22 in it. Same problem- I can get 1 shot off half the time, the most I can get is 2 shots off, then 'click'. When I eject the unfired round, there is a light primer strike visible on the case, so I know the hammer is hitting the firing pin and the firing pin is hitting the primer. So the ammo is normal velocity, and when it does fire, the upper functions as it should, ejects and chambers a new round, the hammer has to be all the way back held by the sear, so rigger pulled, then 'click'. I took the bolt carrier group out, wiped it down and re oiled it...same thing.

SO.....what's causing a light primer hit on a CMMG .22 upper?

[Ian]

I've never owned or shot one and hopefully a expert will chime in on this.

Can you drop the lower on a 5.56 upper and see if runs properly?

What about a worn down firing pin?

[JustShootIt]

Sounds silly but I had same issues a few years ago with a 15/22....turned out to be the trigger wasnt installed properly....its easy to overlook and everything will seem to function fine and it will even fire a few rounds fine, then click......maybe check and mak sure the spring for the hammer is installed correctly.....

May not be your issue, but sounds exactly like probs I had

[WLJ]

Check the trigger pins and make sure they're both still seated properly. Someone here was having light strikes on their AR and one of the pins had walked out.

[Wyldman]

There has been some discussion that certain hammers don't work well with certain rimfire uppers. Something about the hammer being notched? It seems that PlumCrazy lowers may be involved. I'll see if I can find the reference.

[shelbygoat]

I have a CMMG 22 upper on my polymer lower and it works with SS and regular ammo without issue. Got the lower from joebobs

[Wyldman]

It has nothing to do with the lower, it's the hammer that is used in some of the kits. It rubs on something & prevents the action from cycling properly. I haven't personally had this problem on any of mine, but it well documented in a thread on ArfCom in the rimfire section of the AR15 sub-forum. I'm still trying to find the specific thead/post(s).

[kokopelli]

I'm going to deconstruct the lower tonight and see if I can find the culprit.

[guncrank1]

Your hammer has interference or your hammer spring is FUBAR

[kokopelli]

Your hammer has interference or your hammer spring is FUBAR

cranky for the win!!

the $#%^*!! Hammer spring was installed backward!!

fixed it, ran a mag through it w/out a hiccup!

[guncrank1]

Actually
JustShootIt said so first
But I know what is the problem with my powerful physic gunsmith mind

[kokopelli]

Sounds silly but I had same issues a few years ago with a 15/22....turned out to be the trigger wasnt installed properly....its easy to overlook and everything will seem to function fine and it will even fire a few rounds fine, then click......maybe check and make sure the spring for the hammer is installed correctly.....

May not be your issue, but sounds exactly like probs I had

oh yeah! You gots it right, yo!

[JustShootIt]

Awesome.....

Glad it's up and running again.....

Good to know something I posted was useful, lol