Wait there is silver SOLDERING and silver BRAZING.

Silver Solder is a silver bearing solder that melts around 450f

Silver Braze has a lot more silver and some brass and melts over 1200f.

Braze is stronger than solder, butt, solder is strong enough for sights etc as long as you don't use the barrel for a pry bar. Braze is often used to attach things like carbide to the end of a tool. If you silver braze on a barrel the heat can cause problems and you had better but a protective coating on rifleing. Anything tempered will lose its temper if you silver solder on it. Be better off tig welding. Temp is higher, but more localized because you can heat sink the piece and the tig torch gives instant very localized heat, where any kind of gas torch heats up the part slower and the heat has time to travel farther.

Soft silver solder is fine for sights, every thing must fit tight, no gaps, Plus, it helps immensely to increase strength. Something like just a flat bottomed blade on top of a ramp has little strength soldered. Fitted into a groove and properly soldered you would probably bent the blade before it came out. Even a curved bottom ramp that fits the curve of the top of a barrel will be pretty strong properly silver soldered. When I solder a ramp I fit it to a double groove first a wide shallow groove then a narrow slightly deeper one. Make ramp base to fit. Kind of like tongue and groove. The fit needs to be very tight. NO GAPS. Then, flux and tin (heat up and give them a thin coat of solder) both pieces. Then position parts, heat back up press into place firmly, let cool. Very small amounts of solder should come out of joint. This can be removed using sharp brass scrapers. But, if you coat an area with graphite from say a lead pencil, the flux won't remove it, solder will not stick to it.