from what i understand, the difference between shooting steel and brass is that you will get more life out of the gun using brass generally, but its a difference realized after thousands of rounds, not hundreds. also steel case damages the extractor more than the firing pin. i guess it would be...
X2 for the bad extractor
For whatever reasons these go fast (i think cause its held by cotter pin)
Order a new one for like 18 bucks and swap it out, prolly wouldnt hurt either way
Your best bet is finding someone who knows HKs
DO NOT TAKE IT TO ADVENTURE OUTDOORS!!!!!
Sounds like the receiver is tight on the bolt, another century issue
My two worked great. But some has issues
Also, visit robertrtg.com for parts
you can try a few other places to
http://centerfiresystems.com/AK-PSRB-2.aspx
http://centerfiresystems.com/ak-47siderailscopemountpartmntaka16.aspx
http://www.cdnninvestments.com/ak.html