Steel case ammo is not dirtier. What happens is the neck of a steel cased cartridge doesn't expand like that of a brass one, thus not creating as tight of a seal in the chamber. Since the seal isn't as tight, **** blows back into your rifle.
The steel in your extractor is much harder than the mild steel used in a round, so damage shouldn't occur.
I've ran thousands of steel cased rounds through AR's without any issue. If your rifle will run with it, shoot the hell out of it.
I do plan to shoot the hell out of it, just gotta wait for those that thought they where buying gold dump at the new market price of .25 around because so much was bought by "entrepreneurs" who didn't even own a 223 firearm
I've heard the thing about extractors breaking too, but never from anyone who actually had it happen to them. I shot 1000s of rounds of the steel cased ammo and never had a problem... other than being really dirty. I agree with the previous post about weighing the cost of replacing the extractor against all the money saved by shooting significantly cheaper ammo... that is when prices are "normal."