Also, the guns used were modified, to keep the round from falling out when he "spun cocked" the gun.
Regular 92s (and most other guns) will not work right when you spin them around, the ammo tends to get mis aligned and jam.
There was a pretty good article about the guns, the show and Conners a while back in the Rifleman (couple years ago, I think...)
One of the other things that made the dramatic spin cocking work was Conner's height. Being tall, the short carbine didn't hit the ground like it could when spun by someone shorter...
All else being equal (and it almost never is) bigger bullets tend to work better.