Reading some conflicting information regarding whether or not to use any form of lubrication on o-rings and threads on fill adapters. Talking of miniscule smear of safe products to help o-rings seal/avoid tears, and avoid wear on threads.

The guidance from Bisely states NONE at all:

http://www.bisleycountryblog.co.uk/h...ng-a-cylinder/

Other sources advise occasional fractional amount of silicone grease on o-rings - but of course must avoid any contact with metal parts/threads.

Other sources advise use of 'Special Gun Grease' (e.g. Feinwerkbau) possibly on seals and threads.

Appreciate your views on best practice.