Witness Marks--Evidence in Plain Sight

[Luke]

G.v V -

Under category 1 above, I wonder if the torque applied to the barrel by the bullet's drive through the rifling could account for some of the cases where the mark was clearly made by one tool but is slightly offset.

Depending upon how firmly the barrel was screwed into the receiver, it seems possible that over the course of many rounds the barrel might rotate slightly in the receiver.