Unfamiliar with an airgun part called "deposit." Amazon ad shows Hatsan Velox with factory installed male foster fitting, does your Velox use a fill probe instead? WM
Non-petroleum based lubricants, like heavyweight silicone oil, used for treadmill exercise machines, and plumber's silicone grease are non-degrading of "O" rings. Metal-to-metal lubrication is not recommended for silicone. WM
Haven't tried any big dollar scopes, just tried these at a member's suggestion. Impressed by side-to-side bright, clear picture, super sub-compact size and smooth function, all under $250. Just an ideal scope for bullpup airguns, IMHO. WM
Haven't had mine apart but most PCPs have a round groove in breech which holds an "O" ring to seal air from blowing rearward when sidelever/probe fully closed. Air pressure often ejects "O" ring if fired without sidelever fully closed. Hard abrasives and petroleum-based cleaning products can...
Upper right page corner is search function for archives. Recommend searching, "Avenge-X," "Air Venturi Avenger," "DAR Gen. 3," and "JTS Airacuda Standard," for airgun. Search, "Yong Heng," and "GX-CS Series," for compressor. Best of Luck, WM
Had no qualms buying first version of any new platform until JTS scared me straight with the Airacuda MAX, now I gladly step aside and let others roll the dice. WM