Argon would be better than Nitrogen when filling scopes - it is a much larger atom and is NOBLE - and is readily available in most TIG shops. Nitrogen can attack some metals.
The idea of large atom - a larger flaw can still keep in the gas.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder
Joseph Gw> >