The silencer pictured above shouldn't ever wear out. Cheap silencers are filled with either brass or steel wool. The wool breaks down after a few shots and has to be replaced.
I have a Gemtech .45 suppressor sitting at Red Stick Firearms waiting on paperwork to clear. I've put 250 rounds through it and am very pleased. Shooting such a large caliber weapon without muzzle blast and a BANG sounds very bizarre. You can read my blog and pictures about it here: