Quote Originally Posted by Benelli B76 View Post
Old type polyurethanes suffer from microbial degradation and basically disintegrate over a long period time. Some polyurethanes suffer from hydrolysis. Fortunately the new polyurethanes have additives to prevent this and will last far longer than the owner of the gun.

Baz

https://polymer-additives.specialche...n-polyurethane
How long have they been available in airguns?