Mine have never done a thing other than shoot any 22 round I wish to shoot in them. Longevity....can't really say, but I have heard from other 317 owners that have reported as high as a 10,000 round count.

I ran across a spare 317 cylinder and barrel and picked it up, but I doubt I will ever need it. The general warning is not to get to aggressive with brass cleaning brushes and the finish is not that resilient. Other than that....I would not be concerned about it. Nobody that I know of has posted a picture of a blown-up aluminum 22 cylinder. If anybody has one....let me see it please.

You can always replace the cylinder and yoke in a 317 with a stainless one from a new-model 63....even the barrel as well.