Im thinking about:

on hit: builds pressure, when pressure bar is full, activate it with middle mouse to get increased projectile speed(by 20%), and makes a noticible amount of damage to foes(say a...110% boost, and take in mind that the boost negates the dmg penalty too before u say its op), but with a noticable decrease in rof and reload speed(so u can't spam it) also the jarate-like effect duration is halved, so the effect lasts 2.5 seconds(cuz the projectile is under a higher
velocity, therefore the liquid often misses)
pressure lasts for 6 seconds

regular stats:

(hidden) fires beer/whiskey bottles.

-70% damage penalty

bottles shatter on surfaces

if u hit an enemy directly, he takes an effect similar to jarate(takes mini-crits) for 5 seconds

+1 clip


btw 'pressure' is the weapon's boasting ability, thats what makes it powerful, k? thats why there isnt impressive upsides.