It just looks so bad a** as is I wouldn't worry about BUIS. I'd add an optic and a lightweight bipod and call it a day. Just a short bipod to keep the mag off a shooting bench, but that's me. Except I would get the 22 Charger Lite (Limited Availability) with a factory-installed Picatinny-style rail brace mount with integrated QD cup instead of the original Charger Takedown. Then I'd slap a stock on it and turn it into a rifle. That way it would be an integrally-suppressed or non-suppressed pistol, or a suppressed rifle as my mood dictated. It's still legal to turn a pistol into a rifle and back into a pistol. Just don't have a short pistol barrel and stock on it at the same time.