Ok I tried out a couple of things. I remembered that at work there were some left over cans of something called Plasti-Kote spray paint. When i looked in the flammables store there was just this Glass frosting spray left. Still the description made it worth a try. I also found a can of something called Clear Gard which is intended for coating electrical items. Again the description sounded promising as a bullet coating.
I coated ten bullets, RCBS 245 gr. SWC, with each.
Application was quick and easy. Both were touch dry in ten minutes. Both sets of bullets had a slick waxy feel to them afterward.
I used the usual load I use with these bullets of 10 grains Vectan AO for 1260 fps. with my usual floor polish lube this is a consistent one hole grouper at 50 meters from my M94.
Here is the fifty meter (55 yd) group with the clear gard coating. The highest shot was a called flyer.
Afterwards the barrel appeared dirty and the crown was considerably greyer than usual.
Things improved with the Plasti-Kote glass frosting.
Also the barrel appeared cleaner and the crown went back to being black. So I think we can call this a success.
Bear in mind this is shooting prone, unsupported, with the 'scope set on 3.5x at an aiming point not really suitable for 'scope use.
The Plasi-Kote products are sold over here in most DIY and hardware stores, so no doubt you will find them, or something similar elsewhere.