There are two answers for whether or not all AA hulls are compression formed. One yes and one no. I don't want to take a chance on messing up a barrel with a lodged base wad so I guess I will have to check every one I load the first time around to make sure it is a one pc hull.
I haven't seen them, but let's assume Hoss is right. (I'm still loading from garbage bags full of hulls from a commercial range several years ago)
First, get a WIN load pamphlet and determine if the variant AA indeed do load the same as the one piece. If so, not a problem.
Second, ALWAYS take a quick look down the hull to be sure a pebble or other piece of foreign material did not get in it. Fired hulls have been on the ground.
The screening of the fired hulls is important to determine if it it is the type you are loading, it is in good condition, and it is free of debris. After you have been loading awhile, a glance takes all this in, but at first it takes a longer look and a little thinking. I glance down each hull again just as I am putting it on the MEC.
A good shotgun loading manual will have pictures and descriptions of the types of components and how to identify them. You can't have too many loading manuals and manufacturers load pamphlets.
ADDED: It is important to remember that, in spite of the simplicity (and higher cost) of compression formed hulls, there is nothing poison about a quality Reifenhauser type shotgun hull, which does provide maximum room inside the hull for components, better for hunting loads, especially steel shot. I have loaded and fired many thousands of Federal Champion plastic hulls, using the specified Federal matching wads of course, with nary a problem.