I've only used HC to gold the SVU, and a few random games with the M1216 and S12 Shotguns. Never took a pistol into until today...
Holy god are these things good. Especially since they're semi-auto you can land the shots much easier IMHO. Went 40-4 with the damn Five-Seven w/ suppressor and fast mags, with no perks, had a shield on my back, 2 EMP nades, and 2 concussion nades.
Pistols are ridiculous... In core modes I thought they were pretty damn powerful, but in HC even silenced they're wicked...
I'd have gone Extended Mags for the pistol. The reload time is already ridiculously fast.
I put on Fast Mags since I got caught a few times the previous game reloading the thing.
Got the Five-Seven gold that game, which gave me the Diamond Camo for Pistols too <3.
I wear the Shield on my back so when you get shot, the flinch from it usually pulls you right onto the person shooting at you. I usually aim towards the feet too so if I'm firing fast enough/enough bullets it'll bring the recoil to the upper body, rather than over the head if I aimed at the chest.