There are many AR mods to convert an AR to a PCC, and they are fine and dandy.
One of my favorite PCC's is the Marlin Camp Carbine in .45ACP. My friend Ben has one. It's fantastic.
Okay, my choice on this might have been a shock to some. Let's tour my train of thought on this.
I think a proper PCC should not be certain things... heavy, bulky, complicated, awkward, overly expensive... the best example of an ideal PCC would be the classic M1 Carbine, should that gun be in a common pistol caliber. If you pick up and shoulder the M1 Carbine, it's almost pure delight. Imagine if that was in a common caliber using common magazines. Imagine if it had a forward mount for a Red Dot and a mount for a clip on pistol light, such as an M3X. Done. That is pretty much the weapon I'd want as a PCC. The closest thing to that is the Sub-2000.
We have 1 Storm Lover... Cool. No, I'm not being sarcastic because I really dig the gun's looks, and share the same wish about the magazines.