.41 Swiss die question

[Battis]

I formed .41 Swiss from .348 brass and all works well. What is the role or purpose of the mandrel in the FL resizing die in a fired case other than to deprime the case? Neck tension? Is a fired case sized without the mandrel/decapping stem sized properly? I'm thinking that the answer is very basic but Brain is on brown-out.

[elk hunter]

If I understand your question correctly the button on the decapping stem is to expand/size the case neck to the proper inside dimension when withdrawing the case from the die. The neck portion of the sizing die must size the thinnest case neck enough that it will grip the bullet when seated so must make them a slight bit under size then uses the expander button to expand them back for a proper fit.

Too loose and the bullet will slip, with too tight a fit, for a cast bullet, the case neck can size the bullet down enough to cause problems with accuracy.

Hope this makes sense.

[Battis]

The problem I'm having is trying to position the decapping pin/mandrel in the right spot. If you don't crank it down tight enough when it's in place, the pin just pushes up out of the die, which causes the button to be in the wrong place and ruins the brass. When I run the brass through the FL die without the pin in place (after depriming on a universal deprimer), the die still sizes the neck down but it's unsupported by the button/mandrel. The resulting dimensions of the case mouth are the same as if the button/mandrel was I place. The case mouth then has to be expanded slightly (I use a .44 mag expander or a Lee universal expander). I was wondering if this is still sizing the brass properly.

[texassako]

How you are doing it works fine. I don't know why your pin is slipping, but expanding as a separate step is accomplishing the same thing as what the expander button does. It may even be working the brass less if you have to flare the mouth after FL sizing with the expander in. I leave the expander/decapper out in several cartridges that need to be a different neck size than my FL dies happen to make them.

[Battis]

It seems to work fine without the decapper/expander pin but I just wanted to make sure I wasn't missing something.

[bosterr]

I had a problem with the decapping rod/pin slipping in a Hornady size die just like you describe. The cure was to order the new style assembly from Midway.

[dakotashooter2]

Lee Dies ??????? I have 2 sets with the "friction" type mandrels and both of them slips despite torquing them down as hard as I can. Particularly if you are sizing some of the thicker brass or doing a bit of case forming like you are doing. You could try a little dry lube inside the case mouths. I know that mandrel for the 41 Swiss doesn't seem to have near enough taper to it (going in). Its like trying to push a TOP through a tube top first. I usually stepped my way to get close to the proper neck size using some of my pistol expanders before running through the 41 Swiss sizer die.

[Battis]

I took the mandrel out and from what I can see and measure, it doesn't make much difference to the case sizing. Either way, the case mouth has to be expanded slightly for the cast bullets. I'll put it back when I form new cases from .348 brass.