For those who don’t know the history of the 10mm (a few of you, no doubt), here’s a thumbnail: It began in the early 1970s as a 40-caliber project based on a Hi-Power. The performance peaked at a 180-grain bullet at 1,050 fps. Next, it was upgraded to go into the Bren Ten pistol, and Norma loaded the ammo, greatly exceeding the desired specifications in the process.
I shot one back then, and the result was a 200-grain bullet at 1,200 fps or a 180-grainer at 1,350 fps … or so. Adopted by the FBI, they found (to no great surprise) that you can’t get an office full of accountants to pass a handgun qualification course with such ammo.
The FBI kept asking for softer and softer ammo until they had essentially invented the .40 S&W, a 180-grainer at 950 fps. Then, they ditched the 10mm. The world shifted to the .40, and it was left to Colt,
