Hi Gene ... not sure what Mark's claims are ... but if one of them was that the Oswald rifle was not sighted in properly I would be cautious.Mark Lane made a huge deal of the claim that the rifle couldn’t have managed the feat.
YES , it is true that after the assassination the rifle was test fired and was off target.
But any hunter or marksman will tell you that if a rifle scope is bumped for whatever reason , it needs to be sighted in again to regain accuracy. Oswald tossed his rifle aside on the 6th floor .... it was handled and manhandled by many police .... transported by car to sheriff office ... and who knows what else it went through before it was tested.
Bump a scope a couple of thousanths of an inch and it will affect trajectory by several inches by the time it reaches the target