.257 Baker wildcat

[BCL]

My brother has a rifle that belonged to a gunsmith chambered in .257 baker. Apparently this cartridge is formed by necking down .264 magnum brass. How is this done? Is there a die for this wildcat? Having trouble finding info on this cartridge. Any info is appreciated. Thanks

[p246]

You will probably have to go to a company like Larry Willis or others that make custom dies.

[Tuna]

The .257 Baker Magnum was made from.264 Winchester brass necked down by full length sizing in a .257 Baker sizing die. Ackley listed one load for it. 120 Gr. Spire point and 81.5 Grs of H570 for 3480 fps. Dies for it will have to be custom made ones as p246 said.

[Jax]

Thank you brother for your help with this .257 wildcat. This rifle has an unmarked custom barrel on which I had to do a chamber casting. I was also given 6 rounds of ammo after I did casting, which were identical to the casting.
The cartridges are necked/sized down from the .264 Winchester Magnum to a .257. I've done a lot of research and have found reloading data, but what I'm really looking for is case dimensions for the.257 Baker.
Any help with this will be much appreciated!

[Tuna]

If you have the 6 rounds of ammo and the chamber casting then you should be able to get all the information you need from those. Measure each case and the casting in the neck, shoulder, case body, head and length. Then average each dimension for the 6 rounds and see how close to the casting the average is. Should be a bit smaller all the way around.