Most people say to silver solder a bolt handle on (except the ones that TIG them). Looking in Brownells, the have Silvaloy Silver Solder and they have the Hi Force 44, which has silver in it too.
The Hi Force has a lower temp requirement which I like, to keep the temp of the bolt down at the cocking ramp, but is it strong enough? What is the strength difference between the two?
I have the torch to do both.