is an Impact M3 barrel indexed at the factory?

There was a mark ( black marker ) on my Maverick barrel at the top in the muzzle end, so when messing about i have put the barrel in the same way

In my last job i also used a black marker straitening out hardened gear input axles out before grinding them, using a bit heavier means than i have seen FX use on barrels, but also more heavy stuff i was working on.