Standard tin/lead should be fine. Don't use anything with a flux core.
I should add, I'm assuming you have a neckstrap ring from a replacement parts supplier or from a parts horn. The ring usually will already be mounted (silver-soldered) on a wide flange base (round, oval, or diamond-shaped).
Just a wire hook or ring alone with no flange will not provide enough surface area for the solder to withstand the weight of the horn if hanging from a neckstrap.
I should add, I'm assuming you have a neckstrap ring from a replacement parts supplier or from a parts horn. The ring usually will already be mounted (silver-soldered) on a wide flange base (round, oval, or diamond-shaped).
Just a wire hook or ring alone with no flange will not provide enough surface area for the solder to withstand the weight of the horn if hanging from a neckstrap.
