IOWA303:
Neat choice of calibres. Mine are not too dissimilar. Other than ones already mentioned: .22 L.R., .223, 256 Fraser Flanged N.E. (aka .256 Swift Flanged, aka .256 Gibbs Flanged, aka .256 Mannlicher, aka 6.5x53R), .275 Bland (aka .275 Rigby Rimless H.V., .276 Rimless N.E. 2 1/4", aka 7x57), .298 Minex, .30 W.C.F. (aka .30-30), .300 Rimless N.E. (aka .30 U.S. 1906, aka .30-06), .330 Rimless Nitro Express 2 1/2" (aka .338-06, aka .338-06 A-Square), .350 Rimless N.E. 2 1/2" (aka .35 Whelen), .375 Flanged Nitro Express 2 1/2", .450 Belted Rimless N.E. 2 1/2" (aka .458 Winchester Magnum) & .50 muzzleloader, built on a #1 Mk. III receiver

Igorrock:
.256 Gibbs Magnum Rimless is 6.5x55 as loaded for George Gibbs Bristol, England. The base is larger than the 6.5x57, shoulder is different, &c. The Gibbs Rimless N.E. is 6.5x54 M.S., while the .256 Gibbs Flanged N.E. is also known as the 6.5x53R or .256 Mannlicher.

Ref:
The History & Development of Small Arms Ammunition, Vol. 3 British Sporting Rifle Cartridges, George Hoyem, 1985
British Sporting Rifle Cartridges, Bill Fleming, 1993
Cartridges for Collectors Fred Datig, Volume 1 British, 1961

.....Rimless NE 2 1/4".....should have a rimmed case...
Huh???

Ash
Which one? I've got 2 that I'm thinking of unsoldering & throwing away the ribs from (and then, of course, power polishing & hot bluing the rifles to make them all shiny & pretty)?

;-)