I have a number of half sodered German scope rings which have been removed from various scopes . The old solder remains on the rings.
When I want to resolder these rings on a scope tube do I have to remove all the old solder or do I have to tin the scope tube only ?
I would suppose the old solder is 50/50 tin and lead .
Do I have to tin in exactly the same soft solder for the two surfaces to alloy?
Thanks

Ive never soldered scope rings but Ive done a ton of soldering and braising. I suspect that if you use a good flux and match the melting temp of your new solder to the old 50/50 it'll flow nicely. I've mixed solders in the past and they'll flow into one another.