Repressing the barrel is your 2nd to last last resort. The last resort is a new trunion, also called a barrel extension.Sweet. Even I get it now. Seems like a number of different variables can affect - of adjust - bolt gap. I'm assuming it's easier to do the oversize rollers or a new bolt head rather than adjust the barrel ..... it's not as easy as tapping it with a hammer, right?
Normally, either a new locking piece or oversized rollers will do the trick.