I have observed Pristine Mosins shooting left, and Pristine Mosins shooting centered. It seems to be random, and gun-specific. If you drop a left-shooting Mosin for another, it may shoot left or it may not, and it will stay that way regardless of quality.
I don't know if it's a hidden stat causing some Mosins to shoot left or if it's an unintended bug.
Either way, it would be nice to have a windage adjustment to go along with the already-implimented elevation adjustment. This way we can correct for an individual gun/scope/bipod combo.