Moe,
I did some testing on homemade 1/2A wire joiner-type horns. Different solders, different techniques. Data sheets for different solders. If you are interested, lemme know. I had Oatie Safe-Flo Silver Bearing Wire Solder (Sn-Cu-tin-Ag) in my table, but never found a data sheet with shear strength values. Perhaps not surprising for a plumbing solder used in joints with a ton of surface area in the lap joint and all they want beyond that is something that won't leak....
Just in general, the strength of "silver bearing" solder is roughly twice as high as electronic solders, which are very weak. (Harris Stay-Brite #8 with 5.5%Ag vs. Kester "44".) There is a slight advantage if you are doing sequential assembly, where you can do one area with one type, and then using a lower liquidus solder after that and with care, not cause the first area(s) to come undone. If you want the strength of the solder to go up, use "silver brazing" material. That is going to take a torch, not an iron, but is much stronger and not any harder to do.
A critical factor is the joint clearance. You want maybe .0015" gap for the solder to fill. As the gap gets larger, the joint strength goes down.
The easiest way to building in some strength margin using soft solders is to add surface area to the joint. Formost brass washers help and they have precision diameter fits.
The horn in the picture failed at a sustained static load of 11-12 lb. I don't recall the arm length.
I get all confused about particle physics. All I know is that I decay at the speed of light. With or without neutrinos....
The Divot