VA:
I see how you got a little confused. It isn't hard with British rifles. In Purdey's description, there are two references to the rifle being a .450 No. 2. "No. 2 Express .450 rifle" and "3 1/2" case". The only .450 Nitro that uses a 3 1/2" case is the .450 No. 2 Nitro Express. The .500/.450 uses a 3 1/4" case. The proof marks on the flats are standard for a .450 No. 2, not a .500/.450. The rifle was proved for the full 80 Cordite load (marked on the flats, and unique to the No. 2), but regulated with a reduced "Tropical" (75 Cordite) load, which was common practice.
The proof marks on the flats are definitive. The barreled action of this rifle was built up and proved in London before the 1904 rules went into effect. Since the .450 No. 2 was introduced about 1903, this rifle was proved in 1903 or 1904. It may very well have laid about "in the white" quite a while before being finished. When the problems with the .450 bores hit in India in 1906, the .450s got hard to move, so this wasn't unusual for .450s. White Hunter Philip Percival ordered a new pair of .450 No. 2s in 1927. His rifles were actually built up and proved in 1907.
The information from Woodward refers to a Black Powder Express. "Solid bottle case 3 1/4" refers to a modern drawn case, as opposed to coiled brass. "Cannelured copper point bullet - 230 grains" refers to the standard .400 BPE bullet, a metal base copper tubed 230 grain lead bullet. "No. 6 powder 105 grains" refers to Curtis & Harvey's No. 6 black. This load is a touch light, as the normal charge was 110 grains.
Hope this helps.
