Most if not all of your good scopes will have brass mechanicals inside. I know my swfa scopes do. They are resistant to moisture and temp. My old vari x II leupolds that I dialed had some nylon mechanical parts in them. They were not as precise in adjustment as my scopes with brass internals.
The only thing nylon in the Leupold is the little toothed "gear" that provides the little ball bearing with detents to click in. It aint got a goddam thing else to do but to provide "clicks" that's it and that's all. The old friction adjustment scopes didn't have the little gear so had no "clicks". The clicks don't really have anything at all to do with whether the scope adjusts correctly or holds zero.
