Is there any books or drawing anywhere on what is needed to make 38-50 Hepburn out of 30-40 Krag. I can build the expander if I know what or how many steps it will take. Thanks, Bob

If you have the rifle??? it is much much easier to anneal the Krag brass and fireform it. I have done close to 1000 of them and it is a piece of cake.

I can tell you how or someone else will if you want to try that.

I won't go through typing it out if your not interested.

I first anneal.
Then I expand the neck in steps with a .32, .35, 38 and .40 expander die.
Then I full length size down with my .38-50 Remington Hepburn FL die.
With the steps I get no wrinkles or splits or different thickness of the walls; and no misalignment of the neck.
I end up with perfect cases without fire forming them.

If you only expand with the .38 die there can be sections of the body that still need to be blown out by fire forming; or the neck could be slightly out of alignment.
Yes you can make them quicker with fewer steps, but you end up with cases that may not be the highest of quality.

I have not been able to find .30-40 Krag cases so I make mine from .303 British and they end up about .025 inches too short.

To fire form I have used shotgun powder; and half the load for a 12 ga., filled to the top with cream of wheat or corn meal - that is then plugged with a wad on the end.

Dave, the drawing you posted doesn't make any since to me. It should be a strait walled tapered case after forming. It also has a rim which I THINK needs to be slightly reduced. Does anyone have a drawing of the 38-50 case with all of the measurements? Or where I might find one? thanks again, Bob

This is the chamber reamer design to enable you to use modified .30-40 Krag cases or .303 British cases (not the original .38-50 case).

It is not a diagram of the case.

Yes this chamber reamer is for a modern .38 caliber barrel.
It cuts a leade .0017 wider than the .377" groove-to-groove barrel.

This is a Match chamber reamer so there is no need to size the cases - you use fire formed cases for reloading.

My Rolling Block had a 1:18 twist Atkinson and Marquette barrel and was chambered with this reamer.

I shot a .38 caliber Boomer Money bullet that was 310 grains in weight with .378" driving bands that had a nose with a maximum diameter of .368" and was 1.18" long using 50 grains of FFFg.

Harvey Trace's Rolling Block had a 1:14 twist RKS barrel and he shot 360 grain .38 caliber Boomer Mould bullets.

Both of us used .303 British cases since .30-40 Krag are very difficult to find in Canada.

The .38-50 design like most of the old BP rounds was never standardized through an organization like SAAMI. A drawing has limited value unless you are starting to work on a completely new barrel and chamber.
If you are going to reload for an existing rifle some drawing is just a drawing.
You are not making ammo to fit a drawing. Your ammo has to fit and function in your rifle. 
You need to cast the chamber, slug the bore and measure the rim recess if you have questions. There is no guarantee any drawing will match a rifle.

For example there is a SAAMI standard for the .38-55. 
But there is a problem with the drawing for the ammo vs the chamber.
At the max groove dia of your barrel you can load a .380 bullet in WW brass and the max chamber will not accept the loaded round. Switch to thin Starline brass and you can make it work.
If your .38-55 has a .382 groove dia and you want to use .383 bullets even Starline is too thick with the SAAMI chamber.

Yes in both my .40-60 Maynard and my .38-50 Remington Hepburn I was able to interchange .303 British and .30-40 Krag cases.

Both cases have a rim thickness of .064 but the .303 British case has a .005" narrower rim diameter but extractors have no problem with the slightly narrower head.

The .303 British cases were a bit too short but shot fine with some of the grease grooves not fully covered using 50 grains of powder compressed about .230".

Nagy purchased the rifle from me for his wife with 560 .38-50 Rem. cases I made from .303 British (mostly Hornady and Winchester).
The Rolling Block sports Les's old MVA B5 scope - good to see it will again be shooting at Heffley Creek.