I work on quite a few AR's and see stuck steel Wolf cases frequently.

Greenscout is right on the money as far as cases sticking. If you are happy blasting away and are using Wolf it is a matter of time until you stick a case. The older varnished cases were awful. The polymer coated ones dont seem to stick quite as bad but they still will once in a while.
Cleaning with Acetone or Laquer thinner will usually get all of the residue along with a good scrubbing with a chamber brush.
The second culprit is the case material itself. Brass is a very elastic metal and when you are shooting brass cased ammo the case will fire-form to the chamber and then relax a bit. Steel on the other hand is not nearly as elastic and when it fire forms it will not relax so the odds of it sticking are higher. It gets worse the dirtier the chamber gets.
AK's will run Wolf all day long and never wimper about it. AK's are machined to looser tolerances plus the chamber is tapered on an AK so case sticking is minimized.
AR's are machined to tighter tolerances plus the chamber is straight walled so case sticking is almost inevetable.
Wolf will make your AR much dirtier also. It is a dirtier powder blend and with the gas impingment system really carboning up the rear of the bolt and carrier is common.