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?