Floorit;
Yeah, that's the general consensus - if it's loaded in to a pistol, it's illegal (in some jurisdictions; the state of IL being one of them.)
I always wondered how this applied to stuff like Carbon 15 and other .223 pistols though. Mine blew up on me years ago, and all I have in .223 / 5.56 is rifles now, so I don't mind keeping AP on hand in that caliber.
Usually, constructive possession is enough to get you at least arrested & charged (with all crimes, in general, not just firearms). Then it's left up to the states attorney to decide if it's worth prosecuting, then arraignment, and later a judge & jury to convict.
Personally, I don't want to even get to the "arrest" part of that chain.