| .17 Mach IV | ||
|---|---|---|
Left to right: .17 HMR, .17 Mach IV, .243 Win |
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| Type | Rifle | |
| Place of origin | United States | |
| Production history | ||
| Designer | Vern O Brien | |
| Designed | 1962 | |
| Specifications | ||
| Parent case | .221 Remington Fireball | |
| Bullet diameter | .172 in (4.4 mm) | |
| Neck diameter | .206 in (5.2 mm) | |
| Shoulder diameter | .361 in (9.2 mm) | |
| Base diameter | .378 in (9.6 mm) | |
| Case length | 1.400 in (35.6 mm) | |
| Primer type | Small Rifle | |
| Ballistic performance | ||
| Bullet weight/type | Velocity | Energy |
| 25 gr (1.6 g) HP | 3,680 ft/s (1,120 m/s) | 797 ft·lbf (1,081 J) |
| 25 gr (1.6 g) HP | 3,890 ft/s (1,190 m/s) | 849 ft·lbf (1,151 J) |
| Source(s): 6mmBR [1]
Hodgdon [1] |
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The .17 Mach IV is a wildcat centerfire rifle cartridge, based on the .221 Remington Fireball case, necked down to fire a .172 bullet. The cartridge was introduced in 1962 by Vern O’Brien[2] it offered an easy case conversion and good ballistics but could not compete against the .17 Remington[3].
The name Mach IV comes from the claim that bullets can reach 4000 ft/s[4], despite this being only about Mach 3.5. Due to in case capacity, even small variations in powder of 0.5 gr (0.032 g) can lead to a difference of 100 ft/s (30 m/s).
The .17 Mach IV became very popular with varmint hunters, so much so that in 2007 Remington introduced its own very similar version, the .17 Remington Fireball[5].