Thanks for all the replies.
Im polishing to 600 grit and smooth over with grey scotch brite to blend it all together. It gives a sort of burnished effect. Would this be an issue to get the first coat to bite I wonder? Ill try a 320 finish as you suggest with no scotch brite.
I had a look on lothar walther website and they use a Chrome-molybdenum type steel coded LW19. Im pretty sure my off cuts arent stainless steel as they are magnetic and accept the usual cold blue touch up paste which I use to check if the metals will most likely black. Itll be nice to see if I can solve this problem with these off cuts but I think the steel is completely different to the ultimate goal of blacking the William Powel barrels so Im going to source some new test pieces.
I know Johnsons barrel browners can rust blue the walther barrels with amazing results here in the UK so it must be possible but I guess theyve had generations to perfect the art and do it for a living.
Well Ive got a few more things to try now, might take some photos at the different stages, to upload here, and see if you guys can spot something obviously wrong.
JMH
