You can nip that story in the bud now Jona. There were no Armourers in the Royal Engineers either. And if REAL Armourers weren't even allowed to stamp the bodyside, (that part of the rifle could only be marked with an engraving cutter) you can be rest assured that nobody would tell us to grind a part of it away. We have very probably the most comprehensive archive of permissable modifications to Service rifles here at the Small Arms School, and grinding out he US Property mark isn't included in it.
Thunderbox has hit the nail on the head - albeit a bit more diplomatically than me!