Com-Block steel cased ammo was specifically designed to work with their firearms, and their firearms were specifically designed to work with their steel cased ammo.
Com-block weapons have more tapered chambers to allow the steel cases to both feed and extract easier.
Steel cases do tend to extract with more difficulty and so the chambers are tapered to increase reliable extraction.
This sacrifices at least some potential accuracy, which they're willing to give up to get more reliable operation.
Most western firearms are designed with absolutely no thought given to use with steel cased ammo.
Western ammunition was expressly designed to be made of brass. When it's made of steel, some problems may appear.
Most western ammo has straighter case walls, which makes a more potentially accurate round, and still allows reliable feed and extraction with brass cased ammo.
Since the AR-M16 was never designed for use with steel cased ammo, and they use straighter walled chambers for the .223/5.56 round, extraction may be more difficult with steel cased ammo.
It's the difficulty with extraction that may cause damaged extractors.
Steel cases simply don't expand then contract as much as brass cases do, so when a steel cased round is fired, it doesn't contract as much and you may get sticky extraction, which stresses the extractor.