That is a gorgeous rifle CC! Simply stunning and the condition! A good weight for that cartridge too!

With respect to pressures, I have found a low enough velocity, with some powders, to correspond to regulation means the primers protrude, from I am reliably told, the case gripping the chamber walls but the pressure being too low to drive the case back. Increasing the powder charge by a couple of grains fixes this problem. All NE loads in Tropical load proofed doubles, with the 500/450 31/4" Magnum IIRC (or perhaps the 500 3 1/4", I could check my notes). This was with H4350 (AR2209 here). No issues with RE15 and a Kynoch wad.

From Graeme Wright's work modern load pressures using the correct powders are quite under the old factory loads listed, as 93x64mm states above.