When I shoot IHMSA matches with a revolver, out of the Creedmoor position, I use a blast shield made of several layers of glued leather to protect my legs from the blast and potential unburned powder, bullet shavings, etc. I have no doubt that if my fingers ever get alongside the barrel/cylinder gap of any of my magnum revolvers, it will result in serious injury. One more reason for the traditional thumbs-locked grip.