When doing the final sanding/polishing of the barrel before bluing; should it be done longitudinally or circumferentially? What grit size (400, 800, 1200) is adequate for the final pass? Any guidance would be greatly appreciated.

I blast longitudinally but what really matters is that the coverage is even. The grit that you finish with depends what you want the finished metel to look like. I like to sand blast the receiver then garnet blast the barrel. Nice contrast.

I think it should be done both ways. Circumferentialy first then longitudinally, or visa-versa, to remove and discover any marks left from the previous polish. Grit size determines the degree of shine, the shinier you want it the higher polish you will need.

Like Mr.Kobe stated I like to polish in both directions with each grit alternating directions. I plan it out so that my polishing is finished longitudinally with whichever grit I am finishing with.

So, 180C, 180L, 240C, 240L, 320C, 320L.

Same goes for X and Y on a flat part such as the extractor on a mauser

Great help, thanks.