204-308 Wildcat

[1970gmc]

Has anyone heard of a .204-308 wildcat cartridge before? I have a coworker who is a big tinkerer of guns and told me about a wildcat cartridge that he and some friends came up with that essentially takes a 308 case and necks it down to accept a 32gr bullet from a 204 Ruger and chambered in a Savage model 10. I don't know much about it other than he moved the shoulder angle by about 5 degrees and loads it with about 32gr of powder. He also said that his chrono fails to read the velocity of the bullet because it makes out at 4600fps. I'm just trying to establish the validity of his claim. Opinions? Sound legit?

[JMP]

Has anyone heard of a .204-308 wildcat cartridge before? I have a coworker who is a big tinkerer of guns and told me about a wildcat cartridge that he and some friends came up with that essentially takes a 308 case and necks it down to accept a 32gr bullet from a 204 Ruger and chambered in a Savage model 10. I don't know much about it other than he moved the shoulder angle by about 5 degrees and loads it with about 32gr of powder. He also said that his chrono fails to read the velocity of the bullet because it makes out at 4600fps. I'm just trying to establish the validity of his claim. Opinions? Sound legit?

Completely legit. See here as he has similar results.

http://www.calguns.net/calgunforum/showthread.php?t=1218279

The .308 is the most common case for wildcats. With wildcats, you can pretty much do whatever you want with respect to shoulder angle, height, caliber, etc., then you just need a reamer and dies made for it. Finally, you need the right components to load it. The very necked down wildcats are going to need, often, a much slower powder.

I don't recommend wildcats for inexperienced reloaders.

[mjmagee67]

Probably legit.

4600fps should be no problem for most chrono's.

I bet it's a real barrel burner. I would bet the throat is torched before 1000 rounds.

But if he loads with 32grs of powder, that seems light for a .308 case volume. I have loaded my 204 Ruger with 27grs of powder and it has a much smaller case volume.

[Bill Steele]

Sounds like the definition of Overbore.

[Divernhunter]

That is what I was thinking. I use 27 grs in my 204Ruger and get 4000FPS.
A case so much larger and only 32grs? With that much extra space I wonder if the ES is large?
At least it is less overbore than on a 30-06 case

[Wrangler John]

My opinion is that such a cartridge is a waste of money, time, effort and barrel steel.

The lowly .204 Ruger will easily attain 4,000 to 4,200 fps with the 26 grain Barnes Varmint Grenade, or the Hornady 24 grain NTX. Another accurate .204 bullet is the Nosler 32 grain BT Lead free, which does better at a slightly lower velocity, around 3,900 +/- fps. My standard .204 Ruger load is a 26 grain Varmint Grenade driven at 4,085 to 4,110 fps with Reloader 10x. This load in a Pac-Nor 1:8.5" twist, or Shilen 1:12" twist, or Hart 1:9" twist barrel, all these shoot under .5" and some into 10 shot bugholes.

Use of a lead free compressed powdered metal core jacketed bullet is recommended at these velocities to prevent bullet failure.

(P.S.: I guarantee that even the 6mm 62 grain Varmint Grenade will shred just ahead of the muzzle at 5,400 to 5,700 fps - don't ask how I know, but replacement Sky Screens are cheap.)

I like to experiment with wildcat and improved cartridges, but the hassle of making cases, in some instances requiring forming and shortening, inside neck reaming in a die to maintain concentricity when the new neck is reamed from the old shoulder, then full length sizing and trimming, and finally fireforming, is just way out of proportion to the benefit gained. Even just necking down as in the .25-06 from .30-06 is much work done right. So for just hunting buck-toothed rodents, and other little fur bombs, the standard cartridges are adequate.

[Bill Steele]

That is what I was thinking. I use 27 grs in my 204Ruger and get 4000FPS.
A case so much larger and only 32grs? With that much extra space I wonder if the ES is large?
At least it is less overbore than on a 30-06 case

Yeah, the load density is off (it isn't 32grs), unless he is trimming 30% off the length of the case. Mismatch of burn rate and free space. It s spooky enough when you are loading in that zone with magnum burn rates and nearly full cases. Kind of like flying a U2, not a big margin for error. 😉

[1970gmc]

[QUOTE=Wrangler John;18509915]My opinion is that such a cartridge is a waste of money, time, effort and barrel steel.

I appreciate the feedback from everyone. I'm definitely not trying to argue the merits of what he is doing just trying to see if he is feeding me a line. He said that the cartridge was a pain to put together and not worth the effort but that he did it for the challenge and for the hell qof it.

I had a typo in my first post when describing his chrono and the MV of the round. I meant to say that hid chrono maxes out at 4600fps and that his round is going faster than that because it will not register on his chrono.