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.17 HMR
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20-grain (Bad rounding hereScript error g) A Sellier and Bellot .17 HMR round with a light green plastic tip.
Type Rifle
Place of origin United States
Production history
Designer Hornady
Designed 2002
Manufacturer CCI, Federal, Hornady, PMC,[1] Remington, Winchester
Produced 2002–Present
Specifications
Parent case .22 WMR
Bullet diameter .172 in (Bad rounding hereScript error mm)
Neck diameter .190 in (Bad rounding hereScript error mm)
Shoulder diameter .238 in (Bad rounding hereScript error mm)
Base diameter .238 in (Bad rounding hereScript error mm)
Rim diameter .286 in (Bad rounding hereScript error mm)
Case length 1.058 in (Bad rounding hereScript error mm)
Overall length 1.349 in (Bad rounding hereScript error mm)
Primer type Rimfire
Ballistic performance
Bullet weight/type Velocity Energy
17 gr (Bad rounding hereScript error g) 2,550 ft/s (Bad rounding hereScript error m/s)245 ft·lbf (Bad rounding hereScript error J)
20 gr (Bad rounding hereScript error g) 2,350 ft/s (Bad rounding hereScript error m/s)250 ft·lbf (Bad rounding hereScript error J)
Source(s): Hornady [2]

.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by the ammunition company Hornady in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber (4.5 mm) bullet, and it is more costly to shoot than traditional .22 caliber rimfire cartridges. Commonly loaded with a 17 grain (1.1 g) bullet, it can deliver muzzle velocities in excess of 2550 ft/s (775 m/s).[3]

DevelopmentEdit

File:Rimfire 17HMR 22Mag.jpg

The .17 HMR round is similar to rounds developed by dedicated rimfire wildcatters who worked to create a rimfire cartridge with an exceptionally flat trajectory. These wildcatters were seeking to match the ballistics of the obsolete 5mm Remington Magnum Rimfire, which was made from 1970 to 1974, and was to that point the fastest rimfire cartridge ever produced.[4] With 5mm (.20 caliber) diameter barrels and bullets being virtually unavailable at the time (the 5mm RMR was the last commercial 5mm round until the 2004 release of the centerfire .204 Ruger), the commercially available .17 caliber became their bullet of choice. The .22 Winchester Magnum Rimfire was the logical parent case, rather than 5mm RMR (with its unique case head size, which requires a significantly different bolt and magazine), because it was commonly available, and it is a far larger and stronger case than the next largest .22 Long Rifle. The .17 caliber wildcats not only met, but far exceeded the 5 mm RMR's velocities and flat trajectory. The accuracy of these cartridges was also quite good. However, the downrange energy of the 5mm RMR is superior to both .22 WMR and .17 HMR, so there is still potential in the 5mm rimfire for wildcatters.[5]

Hornady, in conjunction with Marlin Firearms and Sturm, Ruger (manufacturers in the rimfire rifle market), followed much the same path. With the .22 WMR case as the starting point, a simple barrel change was sufficient for most .22 WMR firearms to chamber the new cartridge. In 2002 the first rifles and ammunition began appearing on the market. While the ammunition was relatively expensive due to the high-performance .17 caliber bullets used, it was still cheaper than most centerfire ammunition. By 2004 CCI, Federal Cartridge and Remington had each introduced .17 HMR ammunition offerings.[3]

AvailabilityEdit

File:17HMR and 22LR B.jpg

Cartridges for .17 HMR come with bullets that weigh 15.5-grain (Bad rounding hereScript error g), 17-grain (Bad rounding hereScript error g), and 20-grain (Bad rounding hereScript error g), and come in designs such as polymer (ballistic) tipped, hollow points, soft points, and FMJ. The terminal ballistics of the lightweight expanding bullets limit the .17 HMR to small game animals and varmints. .17 HMR ammunition is less common and more expensive than the .22 caliber rimfire rounds, but this is changing as the popularity of .17 HMR rifles gathers momentum.[6] 17 HMR rifles and ammo have continued to sell briskly. It may be interesting to note that large retailer Wal-Mart sells CCI .17 HMR in some of their suburban locations.

Following the success of the .17 HMR, the .17 Hornady Mach 2 (.17 HM2), was introduced in early 2004. The .17 HM2 is based on the .22 LR (slightly longer in case dimensions) case necked down to .17 caliber using the same bullet as the HMR but at a velocity of approximately 2,100 feet per second (Bad rounding hereScript error m/s) in the 17-grain (Bad rounding hereScript error g) polymer tip loading.

File:17HMR rounds2.jpg

A growing number of companies offer .17 HMR ammunition. CCI Ammunition loads all of the .17 HMR ammunition for the CCI, Federal Cartridge, Hornady, and Remington brands. However, the ammunition is loaded with different bullets to different specifications.[7] Ammunition is also available from Winchester, PMC and Sellier & Bellot.

Citing safety concerns about the round's use in semi-automatic firearms, Remington issued a product safety warning and recall notice.[8][9]

Comparison with .22 LR AmmunitionEdit

AdvantagesEdit

  • Higher velocity: 2350-2550fps compared to the popular ≈1255fps .22LR High Velocity. (.22LR Hyper Velocity can reach ≈1700fps)
  • Flatter trajectory
  • Longer range
  • As the round is faster there is less chance of ricochet due to bullet 'break up' at shorter ranges

DisadvantagesEdit

  • Much more expensive
  • Overly destructive at close range for small game.
  • The cartridge is appreciably louder.

Comparison with .22 WMR AmmunitionEdit

AdvantagesEdit

  • Faster flight: 2350-2550fps compared to the Hornady 2200fps 22Wmr 30gr rounds
  • Flatter trajectory
  • Longer range. Bullets expand better especially at 'long' range e.g. 150 yards
  • As the round is faster there is less chance of ricochet due to bullet 'break up' at shorter ranges

DisadvantagesEdit

  • Less kinetic energy
  • Slightly more expensive

See alsoEdit

ReferencesEdit

  1. PMC ammunition site
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  5. Centurion resumed manufacture of 5 mm RMR in 2007.
  6. The Borchardt Rifle Corp. sells parts to convert Ruger revolvers to .17 HMR.
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External linksEdit

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