[Telperion]

I am loading 357 SIG with Lee dies, and each time a case goes through the expander die, it takes a bit of brass from the case mouth. Over time the shavings migrate downstream to the other dies and make a mess. I've tried adjusting the expander die up and down to control the amount of case mouth belling, but I still see shavings. Is there anything I can do to reduce this?

[rcmodel]

Chamfer the case mouths inside & out with a chamfering tool before sizing them.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

[The Bushmaster]

Yup...That's it...Refer to rcmodel's post...

[brickeyee]

Your expander may also have machining marks on it.
Lathe cutting leaves spiral marks (if a power feed is used), especially with t roughing bit.
The lines are shallower with a finish cutter, but still there.
Look at the tapered portion of the expander and see if you see rings going around the plug.
They can be polished, just be sure not to take off too much.

[rcmodel]

I've never seen any Lee dies that rough, or even close too it.

He needs to chamfer the case mouths, just like any other caliber before reloading them. (especially the first time)

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

[trueblue1776]

My Lee .357 sig die does it too, but I'll be damned if I'm going to chamfer my pistol cases. 1200-1500 rounds later it still does it, and I still don't give a $#!% :D.

If they bother you, just clean the die every couple hundred rounds.

[brickeyee]

If the die was smooth nothing would be coming off...

[trueblue1776]

I disagree, the shavings are nearly concentric circles in my die, it is not an issue of a rough die.

[Harley Quinn]

http://www.exteriorballistics.com/reloadbasics/trimming.cfm

Above is some information.

Does'nt the expander ball go down prior through the tightening of the case slightly (resizing)

Then the ball is extracted from below to open it up to the size you are looking for...then place your champher on it to receive the bullet?
If you want to that is.

So how can the ball that is going through a hole bigger, then reduced and THEN as it comes up, making the size important.

It would seem the ball or expander is the culprite.:uhoh:

[Walkalong]

Your expander may also have machining marks on it.
Lathe cutting leaves spiral marks (if a power feed is used), especially with t roughing bit.
The lines are shallower with a finish cutter, but still there.
Look at the tapered portion of the expander and see if you see rings going around the plug.
They can be polished, just be sure not to take off too much.

Yep. Lee expander dies are like this. I polished all the ones I have. They did not shave brass from the case mouth though, unless, like rcmodel said, your case mouths are rough and you have not chamferred your case mouths. Especially after trimming without chamferring it will do what you are seeing.

[Harley Quinn]

True also is because it is turned into a bottle neck, brass will flow to the forward and get thicker and maybe longer.

So there are things to give you a thought and ponder and then fix it or like one guy mentioned just clean the bench up once in awhile ;)

[BigJakeJ1s]

I've had some pretty rough surfaces inside Lee dies, expanders included. I switched to a Lyman M-type expander, and really like it.

Most 357 sig dies have separate expanders, not part of the sizing die like a rifle cartridge die (I have an RCBS 30 mauser die that does have the expander in the sizing die though). Separate expander dies do not cause case length to grow as fast as a pull-through expander in the sizing die.

Andy

[KI.W.]

There is Lee universal expander die from .22 to 416.

[Harley Quinn]

You might run into a rough one occasionally. But the lee is a pretty good item.
You can lap it...
http://en.wikipedia.org/wiki/Lapping

Add the material to a cartridge that is correct and lap.:D
Or return it and go for a different manufacture, I'd try the lapping first.

;)