Introduced by Cor-Bon CEO, Peter Pi, in 1997, the 400 Cor-Bon uses a necked-down, 40-caliber, version of the 45 Automatic case to duplicate 10mm Automatic ballistics using less pressure and with a cartridge design that encourages dependable action cycling. Having shot several of the original pistols extensively, I can attest to just how pleasant and dependable those guns are. As a left-handed shooter, I can make most semi-automatic pistols jam without trying too hard! The day I got to shoot those pistols, I managed to force jams in half-a-dozen high-end custom pistols built by world-renowned pistol-smiths, guns the owners swore never had jammed and never would jam. By jamming one custom Browning Highpower eight times while trying to empty one magazine, I brought tears to the owner’s eyes. So, noting I could not make the 400 pistols malfunction is no faint praise. This cartridge does exactly what the designer set out to do. It is a great option for those who insist on maximum dependability and who will appreciate 10mm performance with significantly less muzzle blast. As with any bottlenecked pistol round, best practice is to apply a roll-crimp after seating the bullet. This helps to lock the bullet in place against chambering forces that might otherwise drive it into the case. I cannot too-strongly recommend getting a second seating-and-crimping die so you can have one adjusted to only seat the bullet and the second adjusted to only crimp the case mouth. Generally, attempting to do both operations in one step is a recipe for damaged and destroyed cases.