Changing the desert eagle and sniper damage values to 50 would make it a two-shot kill which I think is unfair as the victim has no chance to react and defend themselves. I believe it is currently set to 48 to require 3 shots.
As for the spas-12 it has a very high fire-rate for a shotgun so high damage would make it overpowered. It is on-par with the other shotguns relative to their fire rates.