It isn't just the lack of ready made brass that's odd, it's also odd that a 300 grain RN .366" bullet isn't available for the .400/.360 Purdey. Woodleigh even makes a 320 grain for the .360 No. 2, but no 300 grain for the Purdey, which is vastly more common. Only the Swift A-Frame is available in that weight, and I won't use that bullet in a double rifle. It isn't really appropriate for a .400/.360 anyway.

Dieter Horneber makes the brass. Several of us got together an order through Huntington's, and it looks to be good brass. I'll admit that I bought mine just to have properly headstamped brass on hand in the event I ever needed it, but otherwise never use it. The RWS 9.3 brass is just too easy and indestructable.

Between good friends and myself, there are four .400/.360 Purdey doubles - three Evans and one Lang - all of which are Webley products. We're all loading IMR 4350. I've had mine a long time, and have tried most appropriate powders, but found IMR 4350 the clear winner. I usually use custom 300 grain bullets over 51.5 to 56.5 grains. I always work up over a chronograph, and yes, lot to lot density of that powder DOES vary that much, so I can't be any more precise than that. I've always used Federal 210 primers and still do, but am running low and can't find any more.

I've used 270 grain Speer, 285 and 286 grain RWS, Woodleigh, and others, 293 grain TUG, 300 grain Barnes Original spitzers, and 300 grain Hawk RN. I'm currently using the Hawk. In my rifle, the 270, 285, 286 and 293 grain bullets have always shot acceptably well over the same charge I use for the 300 grain.