Originally developed in 1994 by John Rigby & Co., the .450 Rigby Rimless Magnum is based on the .416 Rigby cartridge, necked up to accept a .458 bullet. This cartridge is intended for use in magazine rifles for dangerous game hunting, differing from the .450 Nitro Express which is a rimmed cartridge intended for use in double rifles. The grouping contains five 50-count cases of cartridges, each case containing ten packages of five cartridges. Four of the five cases are factory sealed, containing the full compliment of cartridges, while one case is open with one cartridge absent, making for a total cartridge count of 249. Three of the cases are marked as having 480gr. soft nose bullets, while the other two are marked with 480gr. solid bullets. All of the packages and cases have the typical Kynoch labels. Two extra packaged of spent casings are included along with four loose casings.

Excellent overall, the cases and packages show some light handling/storage wear and almost no fading of the labels. The cartridges themselves that are not factory sealed and available for viewing are also excellent with only the slightest wear.