The .17 Hornady Mach 2, commonly known as the .17 HM2, is a
rimfire cartridge introduced in 2004 by the
ammunition
Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of oth ...
manufacturer
Hornady
Hornady Manufacturing Company is an American manufacturer of ammunition cartridges, components and handloading equipments, based in Grand Island, Nebraska.
History
Joyce W. Hornady began manufacturing bullets in the spring of 1949 with a .30 cal ...
, 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
In guns, particularly firearms, but not #As a measurement of length, artillery, where a different definition may apply, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge ( ...
(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 a very high velocity for a rimfire round. It weighs only 17 grains (1.10 g) vs 30-40 grains (1.94-2.59 g) of a typical .22 LR bullet. The .17 HM2 may or may not live up to its "Mach 2" name, depending on geographic location and conditions, with velocities out of a rifle of 2,100 ft/s (640 m/s). The velocity is nearly double that of a standard .22 LR, which results in a much flatter trajectory out to its 175-yard (160 m) 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 firearm
A semi-automatic firearm, also called a self-loading or autoloading firearm ( fully automatic and selective fire firearms are also variations on self-loading firearms), is a repeating firearm whose action mechanism automatically loads a follo ...
s 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 PMC/Aguila
*
List of handgun cartridges
This is a list of handgun Cartridge (weaponry), cartridges, approximately in order of increasing caliber.
Table of handgun cartridges
Other cartridges used in handguns
Although not originally designed for handguns, several rifle and shotgun ...
*
List of rifle cartridges
List of rifle cartridges, by primer type, Caliber, calibre and name.
File:Cartridge Sample 2.jpg, 350px, From left to right: 1 .17 Hornady Mach 2, 2 .17 Hornady Magnum Rimfire, 3 .22 Long Rifle, 4 .22 Winchester Magnum Rimfire, 5 .17/23 SMc, 6 5mm ...
*
List of rimfire cartridges
*
Table of handgun and rifle cartridges
This is a table of selected pistol/submachine gun and rifle/machine gun cartridges by common name. Data values are the highest found for the cartridge, and might not occur in the same load (e.g. the highest muzzle energy might not be in the same ...
*
4 mm caliber
References
Further reading
*
External links
EleyCCI
{{DEFAULTSORT:17 HM2
Pistol and rifle cartridges
Rimfire cartridges
Weapons and ammunition introduced in 2004