That weapon is the only reason I dont enjoy playing paintball. it's easy to use, easy to tag with and can be coupled with a shield to make someone practically immortal (only dying to grenades which they often camp/trigger to prevent such an outcome.)
I'd personally nerf it by requiring it to be pumped manually after each shot and reducing it's range, mainly to make shotty shielding harder to do and overall reducing the weapon's power. The same reload mechanic could apply to the sniper with it's bolt if you wanted to go that far.
I'm only really saying this because I avoid paintball due to that one gun being the meta. LT is much better because any gun can outplay a shotgun if you have the hands to match it and overall, LT just feels like it's more balanced and open compared to the '1 gun fits all' meta of paintball.