Yeah four guns would have been the sweet spot I believe. Make the pistol undroppable and double your ammo capacity for it and that would give you one slot for a mid/long range weapon (probably the machine gun), one slot for a close quarters weapon (probably a shotgun) and one slot for a fun experimental weapon.

But to those that have played the game if I continue using the dice to randomly choose what I upgrade will that place me in a possibly unwinnable position later? That is how important are upgraded weapons compared to non-upgraded weapons?