Expansion Dies verses Lee Universal Expanders

[noylj]

Please note that the Lee Universal Expander does NOT expand the case. All it does it flare the case mouth. For proper fit and ease of bullet seating, you should use a "real" expander die that will open up the case ID from where the sizer put it (it has to size all case wall thicknesses, so it can't size case ID to ideal setting) to 0.001-0.002" less than bullet diameter. Trying to seat the bullet into a case with an ID that is more than 0.002" under bullet diameter is one cause of the bullet being seated crooked and putting a bulge in the case at the bullet's base.
The Universal Expander works great for bottleneck cases, since the expander plug is part of the sizing die, but not so great for straight wall cases.

[uscra112]

Outpost75 makes a good point about how the temper of the brass affects expanding. A good while ago I was loading .38 Spl for my Colt target revolver, and wound up making three M-die mandrels that differed by only .001", selected as necessary for various batches of brass. The difference on the targets was noticeable, even though I was never that good of a shot using the classical one-hand technique.

[crankycalico]

Precision reloading requires consistent case neck tension, the Lee die does not deliver that.

I find mine seems to stick in the die body, not exactly a way to get a consistent bell. However it HAS worked so far, but it seems to hurt the case mouth in the spots the case doesn't hit the plug correctly.