That's been a huge subject of discussion on the AR15.com ammo board, the observations are that the real haters of Wolf ammo have never shot it, and there is a standing invitation for someone who has actually had a firearm of any kind, damaged in any way by Wolf ammo, this offer has been standing for several years, guess what? NOT ONE SINGLE INCIDENT, while there has been the occasional broken extractor, the occurrence rate is about the same as with regular brass cased ammo.
The chamber does get dirty, the theory is the steel cases not expanding enough to seal the chamber, but that's about it.
Like I said, I shoot Wolf in my "beater" AR for plinking, the good guns get the good ammo, naturally that includes my MP40.