Bob - why shouldn't the tumbler strike the bridle? Maybe I'm misunderstanding what your saying. My opinion is that as a lock goes through the firing motion, the flint striking the frizzen should of course absorb a great deal of the force, but as the frizzen kicks open, the shoulder on the cock should 'stop' against the top of the plate at the same time as the rear of the tumbler strikes the stop on the bridle. To my mind the idea is that there is a sharing of stop forces and they should be balanced, inside and out. I've sure seen a lot of locks with a gap between the tumbler and the bridle stop, or older locks with no internal bridle, and inevitably not only does the tumbler hole in the plate wallow out but also the shoulder on the cock and the upper edge of the plate get bashed up. Old Silers with a big gap between the tumbler and bridle stop are notorious for a severely smashed up upper lockplate - I've sure rebuilt a lot of them. There must be enough residual force following the flint strike to do some damage and I think those old pegs on old bridles sure served a valuable purpose in conjunction with the bridle screw to add a lot of reinforcement to the shock absorbed by the bridle.
Of course a percussion lock is a different story but I'm talking flintlocks here.