Long-winded wisdom on building double rifles is gold-dust, Ron. Keep it coming!

So I take it Force 44 solder is tin/cadmium? The stuff I use in Oz is tin/silver, and despite the presence of 5% silver it still melts in the normal soft-solder range. Not to be confused with silver-solder which, as you say, requires red-heat to flow.

The early literature refers to the process of 'tinning' rather than soldering. Do you know whether they used pure tin a century ago, or did it contain additional metals like the silver or cadmium alloys of today?

Apologies for the questions, always been curious about this.