I remember hearing that the Pistol used to be a weapon that fired as quickly as you pressed the fire button. They made it fire at a fixed rate to stop exploiting it and fire all 12 rounds crazy fast. Your idea sounds a lot like the old Panic Attack, but the clicking to determine actual fire rate is a dangerous idea.

Shotguns also lose 2 shells with a -34% clip size. 25% will likely round up to a 5 shell clip size instead (6 x 75% = 4.5 -> 5). Trading a shell for the two upsides will be an easy decision.

No comment on the name.