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Discussion Starter · #1 ·
Just got back from shooting my new XCR 5.56.

Was using a mixture of USGI mags of various age and 2 PMAGs. Was shooting Federal XM193 with gas setting on 4.

I got thru about 200 rounds before I was getting problems.

What would happen is I would load up the rifle, let the bolt fly, shoulder the rifle and fire one round, then wanting to shoot another all I got was a click. I'd then have to cycle the action to reset the action and it would fire another round then the next wouldn't. I grabbed up one of the rounds not firing and saw it had a slight firing pin mark on it. This happened on all the mags I had.

I'm thinking it might either be a gas problem or firing pin problem. I also had a good bit of trigger slap as well but, I think that can be remedied myself.

Any ideas?
 

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Discussion Starter · #2 ·
Also noticed while cleaning it, that I can't get the gas system to move off of 4. Its stuck or something. I put a drop of oil around it, let it soak, and tried again to no avail. I didn't want to force anything so I didn't stick anything thru the hole in it.
 
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go thru it and check your bolts and pins are all tight and in position. field strip it and look for any damage or abnormalities.

then try again.

part 2 of the break in is going thru it and cleaning it and locktite and recheck bolts. try that at this point.
 

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If the firing pin was striking the primer and it wasn't being ignited as you suggested,then you may be getting light firing pin strikes.If your getting light strikes,have you had a trigger job done?...or replaced the hammer spring with a lighter one? Usually getting a new hammer pin spring or a heavier one will cure light strikes.Some trigger jobs consist of bending the legs on the hammer spring to reduce pull weight,but it also reduces hammer energy that in turn reduces firing pin velocity.
 

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As far as the gas valve not turning,make sure your depressing the button down all the way,they can be a little tight at first.
 

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How old is your rifle? I believe new XCR's are being shipped with the beefier hammer spring now, like the one that came with my 762x39 kit.
 

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Discussion Starter · #7 ·
I just got it a week or so ago, fresh from Robarm.

The rifle was shooting fine for 200 or so rounds and then out of no where it would light strike every other round. If I charged the gun, it would shoot then pick up another round and light strike, pull the charging handle back extract and eject the light strike round, chamber another round, it would then fire fine and the next one would light strike. It did it exactly like that for 2-3 mags. Every other round would light strike.
 

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Did you try firing the light primer struck rounds that didn't go off the first time? if they would go off the second time,then you either have old or faulty primers,or the firing pin isn't delivering sufficient energy to the primers.If there was an obstruction(piece of brass etc)somewhere causing the bolt not to go fully into battery you could cause a catastrophic failure if round did go off with the bolt not fully closed.Check inside your barrel extention just to make sure there isn't anything causing the bolt not to go into battery.If it is only partially closed the firing pin may not be reaching far enough to hit the primer because of it being farther away than normal.
 

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firstly, it sounds like your trigger is failing to reset. This can be remedied by lightly filing the hammer sear surfaces.

as for the light strikes - check your bolt and make sure the tip of the firing pin is protruding as it should. If debris or something somehow got caught in there it could be interfering with the pin coming forward.

Also, is it a 7.62 or a 5.56 you are shooting?

And the gas block - sometimes the dials fit in there pretty snug. This isn't a bad thing. Just use a safety flag or something similar to put in the hole and turn the dial with.
 

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As far as the gas setting...

Do you have a new or old system?

The old system required that you unscrew the nut, lock the bolt to the rear, and push the nipple in before rotating. I don't know about the new system.
 

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Discussion Starter · #13 ·
Its a 5.56. And has the new gas system.

I did lightly touch up that corner/ledge with a dremel wheel when I cleaned the gun after I got home. I'll try shooting it again soon and see whats up.
 

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I had this same problem with an AR I was playing around with. Turned out the bolt wasn't coming forward all the way. I lubed her up real good and kept cycling the action to help break it in. It eventually broke in enough that it ran fine. The only reason I can think of for yours to start out good then get bad is something is caught in the bolt area, probably brass shavings.
 

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Discussion Starter · #15 ·
Did everything everyone recommended and yesterday took it out again. The first 30rd mag went off without a hitch but, as I loaded the second mag I kept getting the problems I listed. I even got a double feed which resulted in a round getting completely smashed up and unshootable.

Any other tips?
 

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What ammo are you using and have you tried different magazines?
 

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Discussion Starter · #18 ·
I don't remember the double feed very well. I just remember looking into the ejection port and seeing a fired cartridge partially extracted and the top most round in the magazine was crushed along the neck and case.

I've been shooting newly manufactured PMC 55gr and XM193. I started my first session with only the XM193 which is normally hotter than most other rounds out there.

Magazines range from an old Thermold, aluminum USGI by many different manufacturers and 2 brand new PMags without the window. I tried shooting the gun with a total of about 15-17 different types of mags and the problem occurred with all of them. I haven't tried my 20rd mags yet but, have a feeling they wouldn't help either.
 
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