38 W.C.F. Dimensions ?

[August]

I'm trying to get a "starting point" for sizing 38-40 brass so that it will run well in my '73.

I got a set of Lee dies.  It looked to me like the sizer die just put a constriction on the neck -- really about half of the neck -- and left the rest of the cartridge unaffected.  Many pards mention that the 38-40 dies need a little shave on the bottom, so I got out the grinder and polisher at took some material off the bottom of the die.

The result is that the resized brass still looks like the die hasn't touched the shoulder and the area of the neck that is being resized seems to be the same as before.  In other words, lowering the die didn't seem to affect the dimensions of the cases at all.  I will say that lowering the die seems to have created rounds that run quite a bit more smoothly in the '73 than those that were made-up before adjusting (grinding) the die.

At this point, I'm wondering what my goal should be for resizing the 38-40 in order to get best reliability.  Prior to "adjusting" the sizing die, I noted a slight, yet distinct resistance at the end of the lever cycle.  This resistance, of course, is very distracting while operating the rifle in 'go-fast' mode.

I am aware that factory round dimensions and actual chamber dimensions are only loosely related in this round.

What should I be paying attention to?  I've already found that O.A.L. has to be =< 1.560 in order for the rifle to cycle at all.  Thanks for any insight you can give me that gives me a starting point.

[Flint]

This is from Jerry Kuhnhausen's shop manual on the Colt SAA

[Sir Charles deMouton-Black]

Actual chambers differ from factory ammo!  I have RCBS cowboy dies, and they leave a very short neck.  BUT, resized cases fit my 1896 vintage SAA just fine.

Don't ask me why. 

Try your resized cases in the rifle.  If they fit, don't worry about it.

[Col. Cornelius Gilliam]

Howdy,

I might not be your brass thats causing the resistance.

Check a sized case with no bullet and put it in the chamber.  With your finger, push it in as far as it will go.  Does it go all the way in to the rim?  If it doesn't, then its most likely the shoulder is not pushed back enough.

If it goes all the way in, make up a dummy round and try it in the chamber.  If there is resistance, it could be the crimp or the bullet is interfering.  If you pull the action closed with the lever, and then extract the loaded round, you should see a shiny area on the case if its the crimp, or the bullet will show rifling engraving.

I have found that every 38-40 1873 (Uberti) that I have seen engraves the Magma bullet design.  They come from the factory with a little to no throat (the transition from the chamber to the rifling).  I believe the original Winchesters were throated this way and the Itallians just copied the design.  They work great with the Lyman (Ideal) bullet because it has no crimp groove and no shoulder above the crimp.  This is a black powder only bullet design since you crimp over the radius of the nose, the powder keeps it from going deeper in the case.

The Uberti 73's can be throated to work with the Magma bullet design (I've done my three rifles, and helped several local shooters do theirs).  It requires a throating reamer and T-handle wrench of a small diameter to fit through the firing pin extension hole.  After thoating, my rifles work good with all bullet designs.

[w44wcf]

August,
I don't have any experience with a Lee .38-40 sizing die, but I do with one of RCBS manufacture.  Your die should at least size the case neck back to the fired case neck length.  The best way to check this, is to apply smoke (use a match) to the neck, then size. The line left on the case neck will show you for sure where the case neck sizing stops.

If you have a pair of calipers, another way to check would be to close the calipers on the start of the case neck then slide them down the neck until you notice the dimension increasing.   

My  RCBS .38-40 die would size the case neck back to the fired case neck length which was just fine for bullets with a crimping groove, but I wanted to use the Lyman 180gr clone of the original .38-40 b.p. bullet that has no crimping groove with both smokeless and b.p.  The problem with using this bullet with smokeless, is that since it is seated deeper into the case, the case neck needs to be longer to keep it from telescoping into the case under spring pressure from the magazine. 

To accomplish this, I used a lathe to remove .10" from the bottom of the die and it works great. I've done the same with my .44-40 die with the same result. I can now size the case to the neck length that I want....either the fired dimension or longer.

Good luck,
w44wcf