.17 HM2

Infobox Firearm Cartridge
name= .17 Hornady Mach 2


caption= Left: .17 HM2, Right: .17 HMR
origin= United States
type= Rimfire
service=
used_by=
wars=
designer= Hornady
design_date=2004
manufacturer=CCI / Hornady / Eley
production_date= 2004-Present
number=
variants=
is_SI_specs=
parent= .22 Long Rifle Stinger
case type=Rimmed, bottleneck
bullet=.172
neck=.180
shoulder=.226
base=.226
rim_dia=.275
rim_thick=
case_length=.714
length=1.00
rifling=
primer=Rimfire
is_SI_ballistics=
bw1=17
btype1=V-Max
vel1=2100
en1=166
bw2=
btype2=
vel2=
en2=
bw3=
btype3=
vel3=
en3=
bw4=
btype4=
vel4=
en4=
bw5=
btype5=
vel5=
en5=
test_barrel_length=
balsrc= Hornady [ [http://www.hornady.com/shop/?page=ballistics/popup&product_sku=83177 Hornady] ] 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 case, slightly lengthened and necked down to .17 caliber (4.5 mm) and using a bullet weighing less than half what typical .22 Long Rifle bullets weigh.

Performance

The ultralight bullet is a key part of achieving the very-high velocity for a rimfire round. It weighs only 17 grains (1.10 g) vs 30-40 grains (1.94-2.59 g) for typical .22 LR bullets. The .17 HM2 may or may not live up to its "Mach 2" name, depending on your geographic location and conditions, with velocities out of a rifle of 2100 ft/s (640 m/s). The velocity is double that of a standard .22 LR, which results in a much flatter trajectory out to the 150 yards (140 m) effective range of the cartridge.

Costs

The tiny .17 caliber jacketed bullet is much more difficult to manufacture than the copper-coated lead .22 LR bullets, and that is reflected in the cost--typically 5 times that of inexpensive .22 Long Rifle ammunition. The price is still less than any but surplus centerfire ammunition, and less than the more powerful .17 HMR. The high priced bullet used in the .17 HM2 does have its advantages, and accuracy is one of them.

Converting rifles

Since the .17 HM2 is based on the .22 Long Rifle Stinger, converting most firearms chambered in .22 Long Rifle to .17 HM2 requires only a barrel change. The higher pressures makes conversion of semi-automatic firearms more difficult, as virtually all are blowback designs that are sensitive to pressure changes. Kits for the Ruger 10/22 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. Since the .22 Long Rifle is arguably the most popular cartridge in the world, the .17 HM2 has a large pool of potential firearms that could chamber it, and a huge infrastructure to manufacture the rimfire case it is based on.

Market acceptance

The .17 HMR was an instant success when it came out, but the .17 HM2 hasn't been out long enough for its success to be judged. Part of the .17 HMR's success may have been due simply to the uniqueness of the first mass manufactured .17 caliber rimfire (.17 Aguila was first, but never mass manufactured), an advantage the .17 HM2 doesn't have. However, the .22 Long Rifle outsells the .22 WMR by a huge margin, and if the .17 HM2 can build on that success, it has the potential to go far.

ee also

*List of handgun cartridges
*List of rifle cartridges
*4 mm caliber

References

*" [http://www.chuckhawks.com/17_M2.htm The .17 HM2] " by Chuck Hawks

External links

* [http://www.eley.co.uk/home.htm Eley]
* [http://www.hornady.com/ Hornady]
* [http://www.cci-ammunition.com CCI]