Eightbore,
Thanks for the added information on the 97 'black diamond' trap guns. I'll have to dig mine out & take a look at the bolt marking again, I was going from memory on the 'engraving', a slanted block print, if I recall correctly. I'm sure you are correct about it being rolled, but its very crisp & sharp, how ever it was done. I always just assumed it was engraved .. that's the trouble with assumptions.