It will help determine where and what the problem will be. Personally, I don't think that removing metal is a great idea unless you know exactly what the cause is and if that will in fact fix the problem.
The first thing I would do is use your hand and touch every surface on the bolt and see if you have any rough areas. You may need to polish it. If so, start with 1000 grit sandpaper and then use a cloth buffing wheel. Only polish really rough/jagged feeling edges, and it really only takes a few light strokes in most cases.
Repeat the process inside the chamber and anywhere inside the receiver the bolt slides. For this you will need a brass brush for cleaning a 12ga shotgun. Put the brush on a cleaning rod, and the rod inside a drill. Run the brush/drill inside the receiver and into the chamber, but not so far as to go inside the barrel. This will help get rid of any rough edges inside the chamber and receiver. Make sure you lube the everloving mess out of the brush and chamber. Then repeat the process with the shotgun mop with cleaner on it, then lube it back up, reassemble and then function test. Repeat if necessary.
I've had to do this a few times with other firearms for the same reason.