We never straightened barrels but there does seem to be a lot of press marks on that barrel. To be honest, I think the AX and numbers is the serial number of the rifle. We didn't number barrels to the rifle when we rebarreled. It was an academic exercise with no value to man nor beast simply because once we'd breeched-up, it was there for life - or until it needed a new barrel again! Just like L1A1's and L85's.