.17 HM2

The .17 Hornady Mach 2, or .17 HM2, is a rimfire cartridge introduced in 2004 by the ammunition manufacturer Hornady, following the successful launch in 2002 of the .17 HMR. Wikipedia
 
Bullet diameter.172 in (4.4 mm)
Neck diameter.180 in (4.6 mm)
Rim diameter.275 in (7.0 mm)
Base diameter.226 in (5.7 mm)
Case length.714 in (18.1 mm)

Hornady 17 Mach 2® 17 gr V-MAX® Varmint Express® Rimfire

Hornady, Varmint Express, 17 Hornady Mach 2, 17 Grain, V-Max, 50 Round Box

$11.17 $8.68