It was done in a lathe, with a not very sharp, not very rigid tool.
The pattern in the lines in the pictures looks like the tool was chattering a fair bit. Could have been from not being sharp, could have been chipped, maybe a bad relief angle...Lots of ways to get a lousy finish with chatter. Unless you are trying to repeat it, in which case, never the same twice!
Cheers
Trev
I realize that I'm talking about something else here, but is the 11° crown still the standard?
It may be that the 11° crown is featured primarily on target barrels. I know that Anschutz uses this crown in their rimfire target rifles (but also on their M1770 .223 hunting model), and Lilja's drop-in rimfire barrels feature the 11° crown.I don't think so... I think the flat deep recessed crown is more favoured in custom jobs...