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Custom wildcat cartridge

AbitNutz

Sergeant of the Hide
Full Member
Minuteman
Feb 19, 2021
376
451
SW Ohio
So I have this waste of time/money idea of making my own wildcat cartridge. The base cartridge is a 45 Win Mag pistol case necked down to .308. It's essentially a .308 Winchester short. I want to work up loads using my LAR Grizzly MKI. I have a barrel maker that will make the barrel and I can get the reamer made for the chamber and sizing die. What I'm wondering about is, how do I about getting the forming dies? I don't believe there is any way I can go from 45 to 30 cal in one pass. I would bet I have to have at least two forming dies, maybe three. I have a lot of experience in making wildcat cartridges, but not designing them.

I just thought I would throw this out there in case anyone else has ever traveled down this path.
 
It would be best to go with at least 3 passes to get that reduction. 4 would be better. Why not start with 308 case and shorten it?
You could get better brass quality and availability.
 
I've placed my order and paid for the barrel and reamer and gotten in line for the custom dies I'll need. It's going to take the better part of 6 months to make this happen.
I have a Sprinco setup in my Grizzly now that lets me tune things up pretty well. But going from 230-grain bullets down to 110 grain will require drastic changes in the recoil spring, hammer spring, and firing pin stop to make it function reliably.
 
I think that’s it!
The case on the .308 Barnes is 1-1/2". The max case length I can use is 1.2. actually, 1.198, which is the length of the 45 in Mag case. I didn't use a 308 case cut down to 1.2 inches. Can you imagine how much you would have to ream a 308 case to get it thin enough to case form into a .308 neck at that length? You could certainly do that but it would be a lot of work.