I recently bought a Sako L-461 chambered in 17 MACH 4 I am not sure what the case dimensions are without doing a chamber cast. If it is close to the 17 FB would I be able to load some available 17 FB virgin brass and safley fire them in the MACH 4 chamber. Do I need MACH 4 reloading dies or will 17 FB dies work as they are considerably priced less than the MACH 4 dies. I really don't want to form brass from 221 FB because of the forming die expence. If I can't easily do any of the above would there be enough metal to rechamber to an "easier to reload" 17 fireball dimensions. Also would some shortening of the barrel take place as the rifle is a fullstock.

Hello Hutt:

The 17 Rem Fireball is an industry-standardized version of the 17 Mach IV. Headspace .002" shorter and chamber neck diameter .005" larger on the Fireball are the primary differences between it and the "std" Mach IV. Todd Kindler did a good job of disseminating his specs, but it is a wildcat and chamber dimensions do vary.

Because of the differing chamber neck diameters, you can usually fire Mach IV in a Fireball chamber, but not factory Fireball in a Mach IV chamber. Even though it's a pain, I'd strongly recommend casting your Mach IV chamber and comparing its neck diameter to that of a loaded Fireball round--you need to determine if there is sufficient clearance for safe function.

Dave Manson

Re-chambering would be a shame......

Could you post some pics of the rifle?

Thanks,
Kevin

quote:

Originally posted by DManson:
Hello Hutt:

The 17 Rem Fireball is an industry-standardized version of the 17 Mach IV. Headspace .002" shorter and chamber neck diameter .005" larger on the Fireball are the primary differences between it and the "std" Mach IV. Todd Kindler did a good job of disseminating his specs, but it is a wildcat and chamber dimensions do vary.

Because of the differing chamber neck diameters, you can usually fire Mach IV in a Fireball chamber, but not factory Fireball in a Mach IV chamber. Even though it's a pain, I'd strongly recommend casting your Mach IV chamber and comparing its neck diameter to that of a loaded Fireball round--you need to determine if there is sufficient clearance for safe function.

Dave Manson

Dave, now I'm really confused!
http://sites.google.com/a/17re...reballcasedimensions

Hello Hutt:

After reviewing the link you provided, I understand your confusion. Without getting into a lengthy and detailed analysis of the dimensions of both calibers, let me re-state that the Mach IV is a wildcat. Even though its dimensions are generally agreed upon, it has never been an industry-standardized caliber. As such, chamber dimensions are always suspect until confirmed by measurement--this is why I suggested you cast the chamber and compare its dimensions to those of the ammo you intend to shoot in it. Knowledge is a good thing.

The 17 Fireball IS an industry-standardized caliber and, when encountered, can be relied upon to meet industry specs. Fireball ammo will fit Fireball chambers without any worry about thick necks, etc.

The comparison I made in my earlier post was between CHAMBER dimensions for the two calibers. The table given in your link mixes some cartridge and chamber dimensions, with a confusing result. For example, case length of the Mach IV was given as 1.432". Since the Mach IV is made by necking down 221 brass, and max case length for 221 is 1.400", it's unlikley we'd ever see Mach IV cases that measured 1.432". If you check SAAMI, 1.432" is the minimum CHAMBER length for the 221. Let me know if you'd like copies of the specs for both calibers and I'll e-mail them to you.

From what we've seen of Fireball ammo/brass, inadequate neck clearance is the most likely problem you'd run into if you shoot Fireball in a Mach IV chamber. Not saying you will, but the potential is there for high pressures if the neck of the cartridge binds in the chamber.

Hope this helps.

Dave Manson

Thanks Dave, a chamber cast as you suggested is definetly in order. ....Hutt

More than welcome.

Dave Manson