RE: Best Cartridges that never became popular?
220 swift - Way too much of a good thing.
6mm Remington - Remington introduced this cartridge with too slow of a barrel twist and it would not stabilize 90 and 100 grain bullets. It was a failure before it ever got started. Where as the .243 was made with faster twist barrels right from the start. It is alsobased on the 308 cartridge and any offspring to a military cartridge are destinedfor excelence.
8mm Rem mag - Well maybe if they had called it a 323 Rem mag. Americans hate the metric system. It also requires the use of a true magnum length action. And the 338 Win mag already had a strong fan base and fit into a standard length action.
458 Lott - I agree 100%.
A few of mine are...
284 Winchester
257 Roberts
35 Whelen
And why is there no .277-08?
And we need a standardized 358 Remington Ultra Mag.