Was looking at .223 case dimensions

[wreckhog]

.376 od, .358 id and 1.76 long. I imagine that if you blew the case out to a straight wall, it would be a rimless .357 super max. Change the shellholder and use .357 dies. Maybe swap extractors on a .357 barrel,  ream some more, and have yet another bigger .35 caliber option. Has this been tried?

[quickdtoo]

It's probably been done as most everything has before by someone!! I just tried expanding a 223 neck, annealed it, then went up in steps 6mm, 6.5, 270, 280, 308, 338 and 358, the neck split at 358, may take an additional annealing, but I think it could be done, then ream a chamber using a reamer without a rim cutter, perhaps a cylinder reamer. It should work with a 223 ejector/extractor. 

Tim

[wreckhog]

Split necks might not even be a problem initially. I have a Max barrel. Could I just trim the necks til the thing headspaces right? Doesn't gain any performance, but it is an easy start. Then ream it out further in phase X. Time to strip a .223 barrel for an extractor.

[mike@nds]

I've thought about the same thing for AR's, and I think you might have some trouble with headspacing on the case mouth.

[wreckhog]

I've thought about the same thing for AR's, and I think you might have some trouble with headspacing on the case mouth.

Isn't that sort of what an AR in .45ACP (Olympic or maybe custom Cav Arms) does? If you drop .357 Max brass into a stock handi .357 Mag chamber, I think that it headspaces off something other than the rim; ie it sticks out.

[quickdtoo]

You can always set it up to allow the extractor to hold the case to zero headspace, there's a work around for most anything.  Of course the purpose of making this round would be to allow the use of the shorter .357 rounds also, that would require the extractor to be swapped out. If you just want more umph, rechamber to 35 Rem.   

Tim

[wreckhog]

The 35 Wreckhog, I like the sound of that.

[gcrank1]

Check with the major (site sponsor?) reamer suppliers with your notion. You will probably find they already have something so you dont have to pay to make a new design at all. Of, course, it will already have a name too.
Quite some years back, In GunDigest, was a write up on a .223 necked to .308. It was called the .30 Apache, I think, and was a stellar performer. In our 'bigger is better' culture we have all these monster capacity cases that just duplicate each others performance while not being particularly efficient and definately not economical.

[bikerbeans]

I think the 7MM TCU is based on the 223 Case.  World must need more 7MM hunting cartridges.