Ok if the perk was somewhat similar to commando but better against big zeds and worse against small ones it would be balanced, the question is how to accomplish that.
You're proposing limited ammo/fire-rate/damage, but I don't think that is possible.
1) Damage wise? If its damage was a limitation against small ZEDs how is it supposed to take out the small ones? A scrake has the life of easily 15 clots how would it be limited damage-wise to take out the clots or weaker zeds? You could add a weakness against them (or extra dmg on fp/scrake) for pistols, but I don't think it would make any sense since sharp weapons don't have that. Actually, that would be an awesome idea for nerfing sharp without turning it into ****: He fires more penetrating bullets that ignore the big guys resistance but don't provoke that much damage on small ones as hollow point rounds, but that's another thread there.
2)Limited ammo/fire-rate? I understood from your explanation that sharp would be butchered and only stay good against big ones. I honestly don't think it would go to the whole gunslinger aspect to run on low ammo, specially if there was already another perk specifically and only against few powerful enemies. Plus I don't think it's fair for the HC: It has low ammo just because it's intended as a secondary weapon, and should be changed if it became a primary one. About the fire-rate the handcannon shoots fast enough to sweep through crowds (it excels against crawlers), but if you don't like it gunslinger would still master the 9mm, arguably the best tool for quickly decaping small ZEDs. Shooting them with the revolver would of course be overkill but pistols are light so you can carry all the perks weapons, I don't see how ammo could become an issue without reducing each weapons' capacity to a crippling amount.
So other than with the damage resistance I don't see how the perk could be bad against small zeds and decent against big ones: 2 of 3 pistols have an ideal damage per round and fire-rate to sweep small/medium mobs without being overkill or wasting too much ammo. Plus precision is not an issue with KFs pistol, at least with the already existing ones.
Again, with that versatility I don't know how you can make it bad against crowd but better than commando against big ones (keep in mind TW has yet to come up with a perk straight bad against crowds, the closest ones being arguably sharp and support, but they still rock due to EBR spam and shotgun penetration).
You make good points; it's good to see arguments. Thanks. (yes, I've already thanked before for posting actual arguments. The thing is, if you reward someone for doing something, then they're bound to do it again)
1) The damage part.
I'll explain in detail:
The 9mm deals 25-35 damage (approx.). The Bullpup deals 16-26. The bullpup fires much faster than the 9mm, which is semi-auto and has its fire rate capped at 5 bullets per second. The bullpup fires twice as fast, has a bigger mag, and more spare ammo.
All in all, the 9mm deals tops 125-175 per second, requires an insanely fast finger and nearly empties its mag, while the bullpup deals 160-360 with 1/4 of its mag, and is consistent (firerate-wise). Oh, the BP reloads faster too.
I wouldn't mind a small reduction in 9mm damage, to 22-32. Makes a lot of difference.
The Handcannon deals 95-115 damage, but can't fire more than 4 rounds per second, has a 8-round mag, high recoil, slow reload times, and a pathetically small ammo stash with only 10 extra mags. The AK, on the other hand, has lower recoil, fires roughly as fast as the BP, but deals 35-45.
The handcannon is, IMO, close to overkill on small specs. It shouldn't be your weapon of choice against them. Though if you do want to use them, save your ammo, kinda like with the M32, but without the smoke and suicide-capabilities.
Keep in mind that two HC shots won't kill a clot on suicidal, and a third will be complete overkill (he'll have ~18 hp left), so it'll be a waste. An AK user doesn't need to worry about such ammo waste, because it deals damage with several bullets. One extra bullet won't make a difference.
That said, I wouldn't mind a small nerf on the HC too. 90-110 seems good.
This makes the HC worse at killing small specs, and the 9mm is severely weaker than the Bullpup at such task. Hence why I say it has more of a hard time against those zeds.
The second part... I'll have to post it later. I must get some sleep (it's 3AM as I post this D: )