My Warthog had three big problems, right out of the box:
1. Would not reliably feed rounds (at least one malfunction every magazine
2. Grip safety would not disengage to allow the trigger press unless it was fully pressed into the frame (my hands don't normally DO that when I shoot)
3. That MSH did cut into my palm, unlike some others here (you lucky guys, you)
Hell-bent on making this my primary carry weapon, I poured a bunch of money into custom smithing. The MSH was replaced with a metal one and the sharp point was rounded. The grip safety was built up more and tuned, so now it works right in my hand. The feed ramp was worked, the extractor was tuned and the trigger was also set at a crisp 4.5 pounds.
I just got it back this past week. Despite the smith forgetting to re-insert the rear sight set screw, I still test fired the thing. It is sweet now. All the problems are gone, and I can shoot more than 20 rounds through it without bleeding from the palm.
I tried the following ammo in it:
Federal AE 230gr. hardball
Federal Hydrashoks 165gr. JHP
Remington Golden Sabres 185gr. JHP
Winchester SXT 230 gr. JHP
The ball worked flawlessly, which is more than it ever did before.
The Hydrashoks also worked well (but they worked well in it before I sent it out).
The Golden Sabres gave me three failures to extract with a spent case stuck in the chamber - caused type 3 malfunctions that were worrisome. I haven't seen enough yet to decide if it was only this ammo, or my gun. I'll watch this.
The SXT worked best of the JHPs. It's also most like ball in the weight and shape of the slug. I'd be interested to know how it performs in ballistic gelatin testing. It is right now the front runner for my carry ammo.
Hope this helps. I tried reading every thread on the internet about Warthogs before I bought mine, and I didn't ever find this kind of post. It seemed that people would either say, "It didn't feel right" or "I love it." Not very objective.
Well, okay, I now can say that I love mine. After a couple more range sessions, I expect it to take its place as my primary carry weapon.