Question regarding .38/.357 dies

[Heatseeker]

I probably should have asked this previously, but here goes:

With a .38/.357 combo set of dies, which die(s) do you use the supplied spacer for?

Being a machinist (sometimes to my own detriment), I set out to modify my set of .357 dies for use with both .38 and .357. Using info from the reloading manuals that I have, I've found that the case length difference between the two to be .136". I assumed that the was the thickness of the supplied spacer in the combo sets. After careful inspection of the dies' bores, it appeared that for them to work for both rounds, I'd need to shorten both the sizer and seating dies. I came to this conclusion after noting that there were size changes in the bores at the bullet seating areas of the dies. It seemed to me that the bullet seating dimensions were critical and should remain the same relative to the case mouth on both rounds.

So, I removed .136" from the sizer and seating dies in my set and made a spacer to the same dimension. I've tested the dies for operation on a couple of sacrificial cases and they still seem to function properly as far as receiving the cases. But will they be effective at their task? Or did I ruin a perfectly good set of dies and need to find replacements?

Sorry for the windy inquiry. All comments appreciated.

[kurac]

um, for full length re-sizing one normally does not use the supplied spacer. The spaces is required for case belling and seating operations.

[sza]

You ruined the dies. Well, at least the sizing die.

You don't need to modify or change the adjustment of the sizing die for switching between .38spl and .357mag. It should be in contact with the shell holder for either caliber. With it spaced up off the shell holder you won't be sizing the full length of the case.

The spacer is designed so that if you set your expander and seat/crimp dies for .38spl, you can then install the spacer and use the dies with .357mag. The thickness of the spacer depends on whether the manufacturer expects you to use cases at the maximum case length (1.155/1.290) or at the trim-to-length (1.145/1.270). If it's around .125" thick, they were probably expecting you to trim all your brass to the minimum length.

[Heatseeker]

... It should be in contact with the shell holder for either caliber. With it spaced up off the shell holder you won't be sizing the full length of the case....

After further thought and running a few cases through the die, that's what I was thinking. Thanks for confirming what I already knew, I'm an Idiot!!!

Anyone have an extra .357 sizer die laying around...

[sargenv]

You can usually pick up a Lee Carbide sizer for $15 and the whole die set is usually around $30. Call it an inexpensive mistake that you learned from

[Heatseeker]

I'm glad I've already resized all of my spent .357 cases. That'll buy me some time until I replace the sizing die.

I should be ok using the modified die to resize my .38 cases for the time being, right?

[kurac]

I'm glad I've already resized all of my spent .357 cases. That'll buy me some time until I replace the sizing die.

I should be ok using the modified die to resize my .38 cases for the time being, right?

Nope, you are going to been a new die. They are kind of tapered on the inside and you screwed that up when you shortened it. My guess is that if you try to size a case it will be real tight in the die and maybe even get stuck. The only way you could use it would be to back it off the case holder the same amount that you trimmed it. As long as you are only using the ammo in one gun it shouldn't be a problem, with multiple guns the variations in chamber dimensions will cause chambering problems.