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XCR-L Won't Load Rounds from Magazine....

3K views 11 replies 3 participants last post by  Sean K. 
#1 ·
So, bought a used 5.56 pistol with a 10" bbl from a member here...finally took it out and it has some serious problems loading a round from the mag into the chamber.

Mags were known to be good (and worked in other XCRs with no issues today) Pmags, Hex Mags, GI aluminum mags. Ammo was all IMI 55 grain mil surp....had Brown Bear steel case 55 grain too, but didn't try to load any of it. Didn't think of it until now.

Basically, the round is fed partially into the chamber but won't close....and can't be extracted/ejected without pogoing the pistol most of the time. When it comes out, the case itself is bent about midway down the case..sometimes severely. I can hand feed one round into the chamber at a time....no issues firing or ejecting. Lower is a 84XX SN. Type 1 bolt & lower, Type 3 gas.

I reseated the bbl multiple times..thinking it might not be aligned right or not deep enough into the upper receiver. That didn't change anything.

While I had it out, it *appeared* that the allen screw for the gas block hole is not in line with the divot for the bbl retention bolt. IIRC, the XCR uses a screw on bbl extension....but I can't see any parting line between the bbl and the extension that would indicate that to be the case. In short, it looks as if the extension and therefore, the feed ramps may not be aligned properly with their center at 6 o'clock.

Am I remembering right?....the XCR bbl extension threads on?

Any ideas what might be causing this other than an alignment issue of the extension?
 
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#4 ·
Can anyone confirm that the extensions are screwed on?

Did confirm the bolt has a broken firing pin. Haven't tried chambering with a new bolt yet. Hopefully tonight if I have time.
 
#7 ·
Yep...that was it. Changed to a spare bolt and it's loading/chambering from a mag no issues.

Now I gotta change the broken pin in the bolt itself.

Never done that before.

Do I need to check for the correct chamfer on the bolt face hole? IIRC, that's a really old problem and shouldn't be an issue for a SN in the 84XX range.

Thanks for the help guys. Had a feeling that was going to be it but your confirmation helped me dial in the diagnosis. Much appreciated. :)
 
#8 ·
Glad that worked for ya, hopefully a snap to swap pins, but still, disconcerning. Your first broken pin? if that is true then thats a little comfort at least because i know you push some rounds through and don't baby them.
 
#9 ·
Yeah...I'm guessing the pin was broken before I got it.

That begs the question: Was the switch to the Type 2 bolt really a fix for broken firing pins? The official reason was to help negate slam fire potential (which with the break I and Carp had could definitely happen)...and lighten the BCG to reduce weight and recoil mass.

That leads me to believe the problem isn't necessarily the pins, but more potentially the channel in the bolt itself...as in if the tapered pin binds on the channel or exit hole at the end, it could break.

This could well be a problem with a specific type 1 bolt...as in, it's out of tolerance from a QC perspective. Could also be the diameter or rate of taper on the pin itself or a combination of the two.

I think I'll try and keep a round count on the bolt and new firing pin I put in and get a feel for when (if) it breaks. Might also occasionally tear it down to look for wear points.
 
#10 ·
Anyone have pics of the Type 2 firing pin separated from the carrier?

After looking over the Type 1 firing pin....there is just a poorly engineered stress riser in them. Wondering if the Type 2 redesign was really more about this issue than anything else.

Mine broke right where the step is built in to go from the smaller diameter pin that then tapers to the much larger diameter where the roll pin goes through the firing pin itself.
 
#11 ·
Also, not sure of the internal bore depth, but could it be possible the firing pin spring is going to block height and causing the break? Not sure if the spring fully compresses during firing

Did everyone who broke a pin replace the firing pin spring at the same time with a new one? I didn't in this case, but may now just in case the spring may be part of the problem.
 
#12 ·
Just an update....gun runs like a raped ape on brass cased M193 from IMI, 55 gr. I did NOT need to open the port sizes in the Type 3 dial. Can't remember what I opened positions 5-7 to (specs are in the gas port stickied thread) but I was flinging brass on setting zero....setting 2 is throwing it between 4 and 5 o'clock (really odd) about 30' with authority.
 
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