Alan Moon, You seem to have very strong opinions on this subject, based on what experience I don't know. Here's a brief explanation for MY opinions. Those manufacturers to whom you refer, are using oven-brazing equipment, not a hand-held torch. They are able to control temperatures precisely, control the cool-down period precisely, and heat-treat later as required. Same applies to brazing chopper-lumps together, These jobs aren't done by some ordinary Joe with a torch and some brazing rod, They're done with metal/flux pastes, a jig to hold everything in place, and into the oven. There have been hundreds of thousands of guns built on the monobloc system, using nothing but tin/lead solder. All that the solder does is to hold the barrels into the mono-bloc, it contributes zero to the ability of the assembly to retain and withstand pressure. THINK ABOUT IT!