.17 Winchester Super Magnum

.17 Winchester Super Magnum, is a rimfire rifle cartridge developed by the ammunition company Winchester in 2012. It descended from the .27 caliber nail-gun blank by necking down the blank case to take a .17 caliber bullet. Initial loadings were with a 20-grain bullet, delivering muzzle velocities around 3,000 ft/s. Wikipedia
Bullet diameter.172 in (4.4 mm)
Case length1.200 in (30.5 mm)
Parent case.27 caliber nail gun blank
Overall length1.440 in (36.58 mm) to 1.590 in (40.39 mm)

Hornady 17 Win Super Mag 20 gr V-MAX® Varmint Express® Rimfire

Hornady, Varmint Express, 17WSM, 20 Grain, V-Max, 50 Round Box