Wildcat brass (necking down)

[D.ID]

In the initial wildcating of a cartridge how do I take a small 30 cal case down to 243 without compromising the shoulder and taper of the base cartridge? Assuming I need a custom die in a caliber that has apparently never bean done, Where do I go to get one and is this the normal rout in developing such a cartridge? I have never considered wildcating until now. Any help or direction may be useful, Thanks.

[406pat]

I'd think the best way, as long as you weren't playing too much with overall length, would be to get a neck sizing die that uses bushings and get a few in between .30 and .243. I'd think a step with a 7mm then 6.5 mm equivalent bushing before finally going down to .243 should be easily doable. Make sure you anneal your cases first and use a good lubricant.

Another consideration in going down that far is that the case may form a "doughnut" of brass right where the neck meets the shoulder. You may have to do a round or two of neck turning in between one or all sizing steps as well.

I'd consider getting a custom set of dies made to your dimensions. This I haven't done but I would assume there's someone out there who can cut them from a dimension drawing.

Good luck!

[ROBSTER]

Contac Lonnie Hummel at Hornday he is a great wealth of knowledge.
robster

[Mikecr]

I agree with 406pat. Use a neck bushing die or forming die(with bushings).
And you should, and will likely need to turn the necks to account for the thickening with downsizing.
I don't agree about doughnuts from downsizing though. They form from upsizing.

You might also leave a false shoulder for fireforming.

[406pat]

I stand corrected on the doughnut. Someday I'll get all my facts straight

[D.ID]

Thanks, for all the help so far. A quick search regarding the false shoulder left me with the impression that it would only be used to bring the shoulder out, right? I am dealing with a tapered case and while I wish to bring the neck in to the smaller diameter I want to minimize impact to the shoulder and taper as much as possible to maintain feed characteristics from a magazine. Is my head still on straight? Thanks

[Mikecr]

A false shoulder is a portion of neck which is left to or expanded to a point the case can headspace from initially. Some folks jam bullets(headspacing off the bullet nose) as an alternate. With enough tension you might get away with this.

This is done combined with annealing to provide solid fireforming.