The half cock position on that "Mountie" is a good safety.....here's where the bad part comes in.....when you go to full cock and then decide not to shoot you must pull back on the hammer, pull the trigger, and slowly let the hammer down to half cock again. Occasionally people let the hammer slip out from under their thumb and they have an accidental firing.

Most hammer guns today have an additional crossbolt or tang safety to protect from that.....they are simplyu not needed as long as you're careful about muzzle control when letting the hammer return to half cock.

My first gun was a Marlin 39A and I litterly wore it out. Every dime I made went to feeding that gun. Not once did the hammer ever slip away from me.......My father forewarned me and I always respected the issue.

BTW there's a hammer spur available for guns with scopes and the spur provides a very large area to hold on to. I recommend the spur even if you don't have a scope...one more thing...that gun will take the eye out of a squirrel in the tallest tree in the county.....they're very fine and reliable guns.