[Wavytone]

Hi Alex,

Once rust starts it never stops - best to cut the area out and apply a paint system that provide electrolytic (cathodic) protection. Wax or fish oil (sometimes applied on cars) won't stop it and it will look pretty daggy after a while as it will collect dust and dirt, which trap more moisture and ultimately it will probably corrode even faster.

The common one is "Galmet" used for "cold galvanising", looks like silver paint. There is another though, used for steel structures for roads - a dark grey, dull micaceous paint used on stuff beside roads. I've used this before and it worked well. Both won't look good on a scope, though.