One difference between a Colt SAA and a shotgun is that when carried in the "field", the Colt is quite likely to be in a holster; the shotgun between one's hands. Thus, in a stumble, unless you land on your holster leg, the Colt itself won't actually contact the ground. And unless you're also carring a long gun in your hands, you have your hands to break the fall. The best you can do with a shotgun, unless you toss it out of the way as you fall, is to let go with one hand (preferably your trigger hand) and use it to break your fall.
Most of my stumbles with shotguns take place in the grouse woods, and in those circumstances, I'm doing my best to protect the gun. In one case, I did a great job of protecting the gun but ended up with a broken rib as a result. However, insurance covered the rib . . .
