Just a quick question---My boss has a Marlin 75C, .22, tubular feed semi-auto----it works fine, in pretty good shape and I wanted to clean it for him. Iv'e never owned one and can not figure out how to lock the action open to clean the bore. It has the horizontal sliding safety in the back of the trigger guard and that's it. Does one of you know how this action can be safely locked open?-------------John R