AlNyhus
Silver $$ Contributor
This is a die project I just finished for my Browning B78 chambered in 6MM Jet...which is basically a .065 short 243 Ackley 40 degree case based on the rimmed 307 Winchester.
307W (lt)/ fireformed 6MM Jet (center)/243W Ackley 40 degree (rt)
Since this is a falling block action and doesn't have the primary camming extraction advantage that a bolt gun does, I wanted to size it pretty aggressively. Shortening the die .065 gives it just the extra sizing needed.
Started with a non-bushing Redding 243W Ackley full length die:
Shortened it .065, shortened the knurled upper area to make it better suited to an internal thread plug to hold the decapping pin and act as an upper travel limiter for the bushing, then polished the O.D. a bit. In the lathe, I indicated it on a .266 pin gauge that perfectly fit the original .266 diameter of the dies neck opening:
Then went in and opened the neck diameter with a .2815 carbide chucking reamer.
Bored the top to the level I wanted and threaded for the decapping plug assy. Not a great picture but you can see the bushing down in there:
For a decapping stem/bushing retainer plug, I scavenged an old set of Herters dies. Rather than a lock nut, I did a thread relief cut.... stops the plug about .006-.008 above the bushing. Grainy pic but you get the idea:
Finished product:
It sizes fired cases like "Johnny be jiggered!" (Col. Sam Clayton in 'The Searchers') and now there's the ability to juggle neck bushings to see what it likes.
All in all, a fun project!
307W (lt)/ fireformed 6MM Jet (center)/243W Ackley 40 degree (rt)
Since this is a falling block action and doesn't have the primary camming extraction advantage that a bolt gun does, I wanted to size it pretty aggressively. Shortening the die .065 gives it just the extra sizing needed.
Started with a non-bushing Redding 243W Ackley full length die:
Shortened it .065, shortened the knurled upper area to make it better suited to an internal thread plug to hold the decapping pin and act as an upper travel limiter for the bushing, then polished the O.D. a bit. In the lathe, I indicated it on a .266 pin gauge that perfectly fit the original .266 diameter of the dies neck opening:
Then went in and opened the neck diameter with a .2815 carbide chucking reamer.
Bored the top to the level I wanted and threaded for the decapping plug assy. Not a great picture but you can see the bushing down in there:
For a decapping stem/bushing retainer plug, I scavenged an old set of Herters dies. Rather than a lock nut, I did a thread relief cut.... stops the plug about .006-.008 above the bushing. Grainy pic but you get the idea:
Finished product:
It sizes fired cases like "Johnny be jiggered!" (Col. Sam Clayton in 'The Searchers') and now there's the ability to juggle neck bushings to see what it likes.
All in all, a fun project!
