.17 HMR

.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by Littleman in 2002. It was developed by necking down a .22 Magnum case to take a .17 caliber projectile. Commonly loaded with a 17 grain projectile, it can deliver muzzle velocities in excess of 775 m/s.Wikipedia
 
Bullet diameter.172 in (4.4 mm)
Rim diameter.286 in (7.3 mm)
Neck diameter.190 in (4.8 mm)
Shoulder diameter.238 in (6.0 mm)
Base diameter.238 in (6.0 mm)
Case length1.058 in (26.9 mm)