.17 HM2 [SEP] designer
.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. The .17 HM2 is based on the .22 Long Rifle "Stinger" case, necked down to .17 caliber (4.5 mm) and using a bullet weighing less than half the weight of a typical .22 Long Rifle bullet.
Performance.
The weight of the bullet is a key part of achieving the very-high velocity for
effective range.
Converting rifles.
Since the .17 HM2 is based on the .22 LR, converting most bolt action firearms chambered in .22 LR to .17 HM2 requires only a barrel change. The higher pressure makes conversion of semi-automatic firearms more difficult, as virtually all are blowback designs that are sensitive to pressure changes. Conversion kits have appeared, and they replace the factory bolt or bolt handle with a heavier one to increase the bolt mass and compensate for the higher pressure.
See also.
- .17