re: how to evaluate vintage braze joints. Magnetic Particle Inspection (MPI) can't test what the stuff can't get to.

This is a negative image radiograph of a Smith barrel (you can see the bulge just forward of the chamber) which would be of no help in evaluating the integrity of the braze joint. There is porosity in the top rib and bottom rib solder, and pits in the barrel bore which can not really be differentiated from defects within the barrel wall.



The dark area just forward of the breech is silver solder joining the barrels

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