.327 Federal Magnum

The .327 Federal Magnum is a cartridge introduced by Federal Cartridge but also sold by Sturm, Ruger, intended to provide the power of a .357 Magnum in six shot, compact revolvers, whose cylinders would otherwise only hold 5 rounds. Wikipedia
 
Bullet diameter.312 in (7.9 mm)
Case length1.20 in (30 mm)
Parent case.32 H&R Magnum
Neck diameter.337 in (8.6 mm)
Rim diameter.375 in (9.5 mm)
Base diameter.337 in (8.6 mm)
Overall length1.47 in (37 mm)