In my 20" USGI profile, 4150, chrome lined, 5.56 chamber, 1/7 twist barrel made by BCM - I finally got a stuck case with Wolf.
Wolf polymer. Approx 650-700 rounds no cleaning. Now, I've gone much longer and had reliability, but I would give the chamber a light brushing when I'd clean the bore. That reflects more on the bolt/carrier just needing lube to keep on running.
Anyway, one got stuck. Rim was like WEG's pictures, partially ripped.
Chamber was nasty. Completely filthy. No chrome was visible at all. Carbon fouling, grime and a heavy layer of burnt case coatings (polymer from Wolf) on it. Chamber literally had a texture to it. Very nasty.
Used Hoppes #9, a short pistol rod and a 9mm pistol brush and scrubbed the hell out of the chamber, going around in a circle like a clock. After a good 5 full minutes, there was a nasty thick "soup" of sludge in the barrel extension. Blasted it out with brake cleaner. Like brand new again. Chrome bright shiny and slick. Looks like the day I bought it.
I do not believe this reflects poorly on the reliability of the AR. About 700 rounds of Wolf (over a few shooting sessions) with ZERO chamber cleaning could be considered abuse.
Even minor maintenance every 300 would have easily prevented this with Wolf.
Filth in the chamber and in the bolt/carrier is significantly less with brass cased USGI surlus ammo such as XM193 and M855. I've had zero problems with those. Then again, this is my first problem with Wolf ever. You get what you pay for.