Interesting .243 wildcat

[AlNyhus]

Here's an interesting .243 wildcat called the 6MM Jet that I'm currently working with. It's the 307W case necked to .243. The 307W is the 308W but with a .506 diameter rim like the 30-30 case. After f-forming, it basically ends up being a .065 short 243W Ackley Improved.

307W(left), f-formed 6MM Jet (center) 243W Ackley Improved (right)

 

[jackson1]

Looks like a fun project. Is it an answer with no question or does it have a purpose? To bad Mr. Ackley has left the planet or your could be in his latest edition. Are you using existing dies? Good luck and hope it is a shooter.

 

[AlNyhus]

Looks like a fun project. Is it an answer with no question or does it have a purpose? To bad Mr. Ackley has left the planet or your could be in his latest edition. Are you using existing dies? Good luck and hope it is a shooter.

I came into this wildcat via the backdoor. I bought a Browning B78 that was chambered for this cartridge so it was up to me to figure out exactly what it was. Initially, I thought it was going to be basically a rimmed 243W. Fire forming proved that to not be the case!

For dies, I'm going to start with some 243 A.I. 40 degree dies. I'll face off a shell holder .050 to start and keep facing it off until it just bumps the shoulder .0015-.002.

Necking the 307W cases to .243 was interesting.....

 

[jackson1]

Very cool. Got a B-78 with a heavy barrel in 22-250, that I bought ne just after the Browning centennial. My great uncles were Colorado custom gunsmiths and friends with PO Ackley, they gave me set of RCBS forming dies for 30-06 to 243, along with a couple of old wildcat chambered rifles. Have experimented making 22-250 and made 35 Brown Whelen, along with a couple of other AI cartridges. Always liked the look of high walled Winchesters, but was never satisfied with the accuracy of my rifle. Have excepted the rifle's limitations, but enjoy shooting it. Did you turn the necks or ream them?

 

[AlNyhus]

The case necks are surprisingly decent on the 307W brass. After necking down (used 5 different bushings with a shortened 308W bushing die), the necks/shoulder were stress relieved before f-forming.

Went to the range with 30 cases to f-form. With four rounds left, it rapped off this group at 100 yds. No flags, gusty winds from 2 o'clock and 37.0 of Re17 (just because I had some on hand).

 

[Zero333]

I really dig the propane wand/tip !

I might make one myself next time I feel like annealing.

 

[Rube Shooter]

Nice to see someone else shooting the B78.