I received a reply from Vincenzo Forgione. He uses a 45% AG rod from Fontargen designated AF 320. This is a flux coated rod. The 45% Ag aligns with a post from Fred Parr recalling; "When I was testing oversized handmade tubes that were reeled very thin I used a similar alloy to make the "Whats holding it together" look but the oversized tubes were not accepted, they in fact were rejected and almost a decade went by before anyone made anything with bigger dia tubes,and of course that was Masi. Masi in Italy joined with brazing methods but when it came to California A45C quickly was adopted and most if not all were made with Cad 45 Silver." Fontargen AF320 ISO 176272 designation Ag 145. Ag 45%, Cu 27%, Zn 25.5%, Sn 2.5%. UTS 420 MPa. The equivalent Harris material is Safety Silv 45T. I have procured the same material in Australia supplied by Johnson Matthey (Sliver-flo 452). Flowability of 2, same as Safety-Silv 38T, so I suspect welding up slope and down slope will not be possible but figuring porosity will be low with the reduced zinc content. I am going to trial a flux coated rod alongside a bare rod with silver flux paste. Cheers.