The baffles all look good? End cap not getting hit?
What's it look like inside the attachment end? If it's not damaged, it might have lost some internal volume. Reach in there and try to feel if there's any build up of crud. I go in with an allen wrench and just try to feel/gauge the build up of crud there. I don't try to gouge or scrape it off.
The stock method for cleaning it from HK is to rap the base cap on a piece of wood. If you are going to ultrasonic clean it, don't use anything with ammonia in it or it will destroy the aluminum.