The .17 Hornady Mach 2, or .17 HM2, is a
rimfire cartridge introduced in 2004 by the
ammunition manufacturer
Hornady
Hornady Manufacturing Company is an American manufacturer of ammunition cartridges, components and handloading equipments, based in Grand Island, Nebraska.
History
The company is currently run by Joyce Hornady's son, Steve Hornady, who took o ...
, following the successful launch in 2002 of the
.17 HMR
.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by Hornady in 2002. It was developed by necking down a .22 Magnum case to take a .17 caliber (4.5 mm) projectile. Commonly loaded with a 1 ...
. The .17 HM2 is based on the
.22 Long Rifle
The .22 Long Rifle or simply .22 LR or 22 (metric designation: 5.6×15mmR) is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of rifles, pistols, revolvers, smo ...
"Stinger" case, necked down to .17
caliber
In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore matc ...
(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 foll ...
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
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.17 PMC/Aguila
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List of handgun cartridges
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List of rifle cartridges
List of rifle cartridges, by primer type, calibre and name.
File:Cartridge Sample 2.jpg, 350px, From left to right: 1 .17 HM2,2 .17 HMR, 2.5 .17 wsm, 3 .22LR, 4 .22 WMR, 5 .17/23 SMc, 6 5mm/35 SMc, 7 .22 Hornet, 8 .223 Remington, 9 .223 ...
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List of rimfire cartridges
Below is a list of rimfire cartridges, ordered by caliber, small to large. Rimfire ammunition is a type of metallic cartridge whose primer is located within a hollow circumferential rim protruding from the base of its casing.
Among the most com ...
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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 sam ...
*
4 mm caliber
This is a list of firearm cartridges which have bullets in the to caliber
In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – rega ...
References
Further reading
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External links
EleyCCI
{{DEFAULTSORT:17 HM2
Pistol and rifle cartridges
Rimfire cartridges
Weapons and ammunition introduced in 2004