Thought I'd attempt improving the factory P12 barrel.... Didn't want to waste more than 20 minutes of my life on this POS.
Don't know what Chinesium it's made off....old rebar?
Very hard steel that's difficult to machine with HSS cutters.
Rifling was very rough, severe chatter marks ... Pushing a pellet through felt like there was sand in the barrel.
I lapped the barrel with 110 micron aluminium oxide... 20 strokes... Then another 200 strokes with a very fine metal polish.
It's a lot smoother now... Still some chatter marks, but I can't polish it further because the bore is very close to being over sized.
I don't know if this will improve accuracy... Will test later.
Re-crowned the barrel.
Barrel twist rate is about 1in 22.