Thread: upper receiver stuck to lower...

I've shot my new LMT MRP twice now. Total of about 250 rounds. I did take the upper and lower apart after getting the gun and did a standard inspection and cleaning prior to shooting. One thing I noticed is the release pins for the upper connecting the lower were very very tight I had to pound the crap out of it to get those pins to release. Finally got them release, put some lube in there and did some shooting. Long story short now the upper seems to be "stuck" to the lower. I can't get the front pin to budge at all and the back one is completely pulled out as far as it will go, but the back end won't release from the bottom. They seem to be stuck even though the back pin isn't connecting them any more.

Thoughts? Ideas?

Is the bolt in battery? If it is locked back that would hold the rear together.

Look through the ejection port or drop the mag and look up through the mag well. Is the bolt forward, or is it backed out of sight some? The only thing I can think that would prevent the upper rotating away is if the bolt is back in the buffer part way.

Or more likely, the buffer retaining pin busted or came out and now the buffer is extended into the upper. You may have ot take off the stock and remove the buffer extension tube.

I have four LMT uppers on DPMS, CMT and RRA lowers and never had a problem.

Thanks for the responses. Before I could check your ideas, I finally got the front pin to release then the upper almost shot away from the lower like a rubber band. Something wasn't right that's for sure. I'll have to check the bolt next to to see the position.

Sounds like the buffer spring was compressed and the BCG was all the way back. When it released, all the tension pushed back.

It used to happen often with the L85A1 with new recruits, except there, the entire recoil spring/rod assembly goes flying about 20 feet, which at night can be quite comical - for us training staff - not for the recruit.