Your Primary and Melee weapons can all be upgraded up to three times at the Pack-a-Punch machine, as well as any Wonder Weapon you may have to hand. The actual firepower enhancement varies depending on the gun or melee weapon you’re using, occasionally comes with surprising effects, but usually increases the potency, chambered ammo, and ammo reserves of the weapon.
Though you may elect to keep the current cosmetic look of the weapon you’re Pack-a-Punching by toggling PAP camos on or off in Settings, each of the three PAP tiers include an impressive, and usually glowing camouflage, as well as a change in audio, especially when firing the weapon.