Most wildcats already exist, so reamers and dies are available to rent or buy.

If yours is truly unique, then you need to have a reamer made $$.  They form fire a case and send it to RCBS and they will make a custom die $$$.  then you are set to develop your loads.

I'd suggest you first check to see what others have done in wildcat cartridges of the same bore diameter.  You might find an existing wildcat that "is" your case or a close version.

What are you design thoughts to date???

You might invest in the RCBS disc with ballistics and a "Cartridge design program" that lets you design anything and it will give you a nice drawing and spec including case capacity.  then try a Powerly computer to get velocity and loads points.

BEAR

Crazy;

Get the current edition of "Cartridges Of The World", & go over the wildcat section.  As Bear says, you'll almost certainly find something there that will fill your bill.  And, it'll have the added advantage of providing at least minimal reloading data.  You'll also get a history & development blurb, which will go a long way to starting you on the correct course for any given wildcat you want to adopt.

900F

thoughts.

The 50 bmg has a case head of .804.  Most commercial actions will not accept this large a case head; so you are into expensive action/stock.  The 50 has one heck of a lot of case capacity.  My guess is to beat the 340 Weatherby, Lapua, and the 338 Rum in velocity you will need a barrel at least 30+ inches long.  Which is fine, if it fits your desired rifle.  The 50 holds at least 225 grains of most powder.

If you are looking for a long range boomer (the 50 bmg is that already) you might look at the 416 Barrett.  I've got no hands on experience with shooting or loading such round but it is available with actions to fit also.

The 378 weatherby is another great round, and you can fine some if you look hard.  they were not popular as they just kicked too much to shoot from the shoulder often.  But they do fit the Mark V action.

Just some thoughts.  If you let us know "what "your wants are we could give some more suggestions.

If you want a 338/50 bmg; the 338/50 Talbot is available it is a 50 bmg necked to 338.  It shoots 250 grains behind a 250 grain bullet to give you about 3700 fps.  As I mentioned you get 250 rounds before the overbore will destroy the throat and accuracy is gone???  Interesting to note is that the full case capacity can not be used and the max vel/pressure is a 77 percent full case capacity.  Just too much volume.  This is obviously a dead wildcat cartridge.  But Skip Talbot was the case designer Talbot Custom Equipment, Fallon Nevada.  Skip was a competitive shooter, and past away 2 years ago, his son may be running his shop but I’ve not hear that.  At a price, RCBS has custom dies for this.

BEAR

thanks for the info I'll look into the talbot cartridge, and the others you mentioned, the Idea is to push a .338 cal bullet to 4000 fps

before use ask, because I want to!

The Talbot (338-50bmg) could only hit 3700 fps allegedly.  There are just to many diminishing returns in cartridge design.  but good luck.

I'd start with extra long barrels, 40".  the longer the pressure (even if reduced) is in contact with the base of the bullet the more it accelerates.

Let us know what you decide.  and post some pics if you build it.

BEAR