I "got by" for awhile with the Lee expander die while everyone talked up the M die.

I finally tried a M die, and saw what everyone was talking about.

Now I have them for 22, 308, 32, 357, 44 and 45.

There is no comparison between a normal expander and a M die.

Remember if the bullet scrapes the side of the case, there goes your accuracy and you may get leading.

Get the M die.

Standard case mouth expander works fine, but the glitch is you need to hold onto the bullet to keep is square to the case as the bullet  are entering the bullet seating die.

Think this as you are levering the bullet and case up into the bullet seating die via the ram/cross plate.


And all the case needs to be flair is about this much as the bullet is being pressed into the case, the mouth edge is not going to shave the coating isntead.



On the M expander, it steps the top of case outwards in a slight ring step, so when you set the bullet on the case, this ring will hold the bullet straight up and down with the case, so you don't have to ride the bullet up with the ram/shell plate into the sizer instead.

I always seat and crimp in separate dies.

You can do both in the same die, but you will soon discover the down side of this.

Again, any standard mouth flaring tool will work with coated bullets; be the expander a Lee expander, or more expensive expander die isntead.

So if you are hand feeding the bullet to the case with standard flaired case mouth, then just hold onto the bullet square to the case as you lever up the case and bullet, so the bullet enters the bullet seating die square to the die/case, then case as it being seated by the dies seating stem.
Hell, take reloading 223 or 308 when you are setting bullet in the cases by hand, since these die seats do not come with a mouth expander to begin with, and you get used to holding the bullet in line with the case as it enters the die anyways.

As for  the M type expanders, including M type powder through expanders like the Mr bullet ones, is as the bullet either drops into the case from the bullet feed drop die, or placed in the case by hand, the M top ring allows the bullet to be initial installed into the case squarely, and will stay square to the case as you levering up without having to hold onto the bullet instead.

So standard expander, the bullet will always be a little tippy, and you want to hold the bullet in line with case until the bullet enters the bullet seating die.  With M flairing (with top step) the bullet stays straight with the case instead.


Truth it, for decades before the bullet drop die systems, there was no M expander's, and we all just learned to use standard expanders without problems. The M expander hit the market for bullet drop dies so the bullets would stay straight from the drop of the drop die  onward, and seems that everyone and there mother now just has to have the M dies for even single stage press work as well.