Winchester Model 1907 - Grandfather of semi-autos?

[DWalt]

The .401 WSL has about the same muzzle energy as the factory standard .45-70 loading.

T. C. Johnson was a prolific gun designer for Winchester, and he was pretty good at finding ways to circumvent Browning's patents. This is an article about him.
John Browning's Contemporaries: The Guns of T.C. Johnson -The Firearm Blog

The usual starting point for making .351 WSL brass used to be by modifying .357 Maximum brass by trimming to length and doing a little lathe work on the rim. But I imagine that finding .357 Max brass would be quite a challenge today. I have read that .223/5.56 cases can be converted to .351, and that is probably more feasible. I have not previously heard of converting 7.62x39 cases to .401. I would probably do that if I ever got my hands on a Model 1910 - which is highly doubtful.

 

[Mike SC Hunter]

I have almost a full box of .351 Remington brand ammo languishing in a drawer. I open to offers.

 

[2152hq]

The great thing about using 7.62x39 brass for .401 is that they don't need trimming to length after opening them up.
I guess I could take a skim off the mouth of each but I don't.

IIRC a .38spcl/357 shell holder works w/the case.

I use a converted 45acp expander die to open the x39mm case to 41 cal in one pass.
It's simply has the 45cal expander tapered from just under 30cal to 41cal.
One past into the die and the case is opened up.
Then right to the 41Mag dies.

The 41Mag expander opens the case further down so the bullet can be seated.

The initial formed case looks kind of strange as it is 'wasp waist' in shape from the expanders not being able to uniformly shape from the inside.
But that fireforms on the first shot and you get what you see in the previous posted pic.

The 41Mag bullets are a touch oversize at .410 for .401SLR which should use a bullet of .406/.407
That's why I use only lead 41Mag bullets.
When first seated in the case the 41Mag bullet can slighty bulge the case depending on which brass mfg you use.

But the last step is to run the loaded, bulged round back into the FL sizer 41Mag die. An educated depth, enough to resize the bullet and bulged end of the case back down together. I does so very easily.

I have a .400d LEE bullet sizer push thru die that some day I will polish out to .407 so I can size the 41Mag bullets for use. Just never seem to get around to it.
This method works just fine for lead bullets.
I wouldn't use jacketed bullets w/o sizing them down first.

Roll crimp the bullets firmly or recoil will dislodge them during firing. The rifle does kick.

The orig case headspaces on a semi-rim.
The x39 case does have a very slight semi rim,,only about .005. But it's more than enough to do it's job.
I have found Winchester brass the best for this use.
I have also used Sako, but that's too thick in the neck and will need neck reaming.
Something that can be done of course, but I'll save that work for when I run out of Winchester brass.