Thread: .17 Mach IV Barrel

Right time for another one..
This time a little fast mover for the CZ 527 switch barrel.
This is another great condition but used S/S 1-9" twist barrel that also came with some Redding dies, 150 brass and 3 boxes of 25gr projectiles.



There was a gap in my arsenal, I was also considering a .20 Vartarg but I have never owned a .17 centerfire and I guess its time.
I can see a real neich for this cartridge with some of my 200 yard + hare shooting jobs over newly planted maize crops they destroy in a few short nights.
With all the larger dairy farms shrinking to lots of lifestyle blocks and housing the .223 can be a little too unsafe but with projectiles half the weight and 1000fps faster there is less chance of projectiles not exploding completely on impact.

The .17 Mach IV

Students of history are quick to point out that while the .17 Remington is considered the most popular .17-caliber cartridge, the .17 Mach IV beat it to market by about 8 years.

Introduced by the O’Brien Rifle Company in 1963, it wasn’t very far behind the introduction of Remington’s aggressive little .221 Fireball.
This in fact was the basic case for the Mach IV, all you have to do is neck down the .221 Fireball to .17 caliber and voila, you have the .17 Mach IV!
After its first fire form the overall length stays the same (1.400"), but the shoulder angle changes from 23 degrees to a more traditional bench rest short-cased 30 degrees.

Although printed load data for this is some what on the snow flake side the Mk 4's claim to fame was 4000fps with 25gr projectiles.

Much later to the party in 2007 Remmington released the .17 Remington Fireball as a response to the .17 Mach IV wildcat that had gained popularity in the states with varmint hunters.

Although both the .17 mach IV and the .17 Fireball were both based on the .221 Fireball cartridge they are not identical.
For liability and various other reasons Remington made the .17 Fireball cartridge a fraction longer in the body with a shorter neck and thicker at the base and shoulder diameters than the .17 Mach IV.
Intentionally this means the .17 Mach IV cartridge will fit in a factory chambered .17 fireball but the .17 fireball factory rounds will not fit in the .17 Mach IV wildcat chamber.

While this factory clambering enabled many non hand loaders dabble in this little varminting hotrod most hand loaders still preferred the .17 Mach IV with its longer neck and the availability of quality Lapua .221 fireball brass over the very underwhelming Remington brass that was fast getting a bad name for stretched primer pockets after only a couple of moderately charged loadings.

Factory loads drive a 20 grain bullet around 4,000 ft/s. Velocity is close to the .17 Remington but with significantly less powder, and therefore less heat and fouling. There are also many more published hand loading options for the .17 Remington Fireball that push the variation of .17 bullet weights now available.