When I picked up my CMR, the seller cleared the rifle and emptied the mag. I ran the charging handle and pulled the trigger before I bought it. Got it home and the charging handle now pulls back, then the bolt sticks and the charging handle moves freely back and forth. To get the bolt closed, I have to pull the charging handle back all the way and pull down the bolt release, only then will the trigger work, then the next time I pull the charging handle back, the same thing happens. Something is catching the bolt and sticking it. Anyone else ever have this problem? Could just need cleaning, but wondering if there's an easy fix for it?