New MRP - stuck casings

[Barron1]

Sorry to bother with two questions in as many days, but here goes. Fired the new LMT today and it is very very tight. At first could not eject a live round using the CH. Gun fired and extracted for about 10 rounds then had one stick in chamber. Most of the time the bolt stayed in battery. Once the case alone was stuck. Ripped out a couple of primers, one of which was stuck in the lower causing trigger to fail to reset at all. I lightly cleaned the chamber and bore and BCG before range trip. Ammo was xm193 and PMC brass - both had the issues. Got about 50 rounds out before calling it quits. 4 stuck casings or so total.
- Does it just need to break in? Should I ream the chamber? Any help greatly appreciated.

[tpelle]

Ripped out a couple primers? How does that happen?

[Paulo_Santos]

It sounds like an over pressure issue. You could have a tight chamber or bad ammo. I'd try new ammo or if you have a reamer, you can just drop in the chamber and ream it out.

[Eric]

Normally I would blame the ammo, but it sounds like you tried a couple different factory loads already. If it is blowing primers and fired brass is getting hung up in the chamber, I would have the chamber gauged. It's unusual for an LMT to be out of spec (not a true 5.56 chamber) but stuff happens. If you don't have access to the gauges, get LMT on the horn and get it squared away.

[Barron1]

I have not been able to speak to LMT yet; a google search found a posting where a guy with and MWS had the same problem and LMT told him to run 100 rounds through and it should be good. I found a couple of postings from MWS owners that were similar. As tight as this thing is I don't know that 100 rounds is going to get the chamber ok. The PMC was .223 and it was sticking as well. That makes me think it might be a break in issue? I can't imagine the chamber is so out of spec that low power .223 would exhibit these problems. I'm also not sure if the primers came loose during firing or during my efforts to clear the chamber. Thanks all for the help.

[mtdawg169]

Sounds like the chamber wasn't reamed properly. I would contact LMT and send it in for warranty work. If it's popping primers and getting stuck cases, the chamber is too tight.

[Barron1]

update: going with the "fire 100 rounds through it and it will be fine" advice, I ran 80 rounds through it after a hunt yesterday and had no issues. Using the CH to clear a live round is still more difficult than I would like, but much easier than before the gun had been fired at all. I'll get on the phone with LMT this week and see what they say. I used 80 rounds of xm193. I also did a good chamber cleaning before those rounds were fired.