Sometimes, a good loading just can’t get a break. The 10mm was introduced in 1983, based on suggestions from Jeff Cooper. He’d imagined a cartridge that could match the speed and flat trajectory of the 9×19mm with the heavier projectile of a .45 ACP, basically splitting the small/fast vs. large/slow debate down the middle.
This had been tried before, of course. The .41 Magnum was an earlier attempt to reconcile the .357 and .44 Magnum loadings. Based on the .400 Eimer wildcat cartridge, it could propel a 210gr bullet at 1520 ft/s, dumping a biblical 1080 ft/lbs of energy (1). Sadly, the .41 never caught on, and it faded into a sort of semi-obscurity, kept afloat by reloaders and aficionados who saw its potential in a wide range of loadings.
I wonder if it might have succeeded given a catchier name…something like .400 Lightning. Or the Four Bore Groin Punch. Continued...