i just did the math and figured out the kill times. im not sure about the shotgun but im willing to bet a lot that its easily the slowest killing gun in the game unless it stacks.

Starter- 8 seconds
44 colt- 6.3 sec
pearl- 5.6 sec
machine gun- 2.88 sec

i really don't care what the walk speed is. But lets go into theory here. So no moving, fire at same time, all shots hit no matter what. Machine gun will beat any gun by a longshot. All of the guns need to be buffed up to the machine gun when it comes to damage, the whole freeze and crap can wait until kill times are done. These are more important than anything, no arguing. Also the time to kill gap is easily as bad than era. The gap is about 5.12 seconds between high time to low time. Eras is 5.8 and zones is 1.635. What the **** ol west? Here is how tedious this is in theory if we were to try to get everything to keep their ROF stats and what not but increase the damage to be on par with machine gun

Starter- BUff it up to 10, 4 seconds
Colt 44- Buff it up to 13, 3.2 seconds
Pearl revolver- buff it up to 15, 2.8 sec
Machine Gun- 2.88 sec.

With the edits i made, i closed the gap to 1.12 seconds. All guns would be able to defend themselves and stand a chance against a top teir weapon. Now in theory the pearl is the best gun. However while it may be the fastest kill, it could suffer from horrible manuverability. The guns should be rebalanced around the damages i posted.