Seriously, I think reading the FAQs here should be required before most folks buy an AR15.
I was at the local gun shop Monday when a guy brought in a Colt AR15A2 post ban. He had locked it up with a spent case and a section of GI cleaning rod in it. After another "expert" had given up, one of th eowners and I tried to get it squared away. We removed the buttstock and buffer tube. ook out the buffer and spring, then tapped the charging handle and freed up the bolt. I held the bolt and the owner of the rifle held the upper while the store owner sed a hammer and punch to drive the cleaning rod section and a bent over cleaning mop out of the case. Got that done and the rifle reassembled after assessing the parts for damage.
Why the hassle?? The guy had been shooting Wolf ammo for a couple of weeks and only running a rod through the bore from muzzle to breech once a week. When it FTE'd, he pulled the bolt back and put the rod (with cleaning mop) into the case and hit it with a hammer (hard enough to break the rod) and to release the bolt which tried to ram the now oversized case mouth into the chamber.