Attrition....replace them if or when they break.
I've heard of folks getting 60K through their Kimbers before replacing anything.
I'm at just over 2K in my Cust II...not worrying.
"You need a shotgun, man, it's got a good spread.
It's easy to load, doesn't have a lot of working parts...ya ain't gotta be that accurate, the further away you are the more **** you hit."