i had this problem with my 700. have never had a problem with a higher end rifle such as the remington 700. when i went to the range i shot it twice and the second casing stuck. we (me and the range master) had to use a rod to knock it out. i noticed there were rings on the casing. i took it to my buddy who is a fine gunsmith and we ordered a new barrel because the there were a few tiny spots that were cut to big in the chamber. the only way to figure this is that the barrel was unstable during the chambering process. but what happens is the casing expands into the grooves and locks into place. now you can be thankful brass is soft because otherwise the casings would not come out. good luck i hope its just a bur that can be removed because barrels arent a dime a dozen.