expander diameter for 45acp

still working on better reloads for my 45 i want to try the zero swaged 185gr what would be the diameter of the expander die to use that would not squeeze or under size the soft lead? I am using a dillon square deal and my expander measured .447 and when I load one and then pull the bullet it has been sized down to .449 but dillon said they don't make a expander for soft lead bullets thinking about having one made.

Both my RCBS expanders measure .450"  My Dillon powder funnel is   oval shaped  and runs from .448" to .4495"  Dillon would not replace it.  

when I told them mine was .447 they told me that was the correct size, I think that guy was Just not up on his dimensions. I think .450 would be good for .451 jacketed and hard cast, but think for soft swaged lead .452 diameter bullets .451 would be better.

243winxb wrote:Both my RCBS expanders measure .450"  My Dillon powder funnel is   oval shaped  and runs from .448" to .4495"  Dillon would not replace it.  

If you have one made, consider having it made in the "stepped" fashion of the Lyman M-type expanders rather than a belled expander.  That way you can expand deeply enough to hand seat the bullet into the case mouth rather than just setting it on top of the "funnel" and hoping it starts straight.

+1  that's a great idea if you are going to all the trouble to make one.
Be sure you polish the expander well too.

Don't assume. Zero and many other swaged bullet companies don't use dead soft lead, they use 92/6/2—which is hard enough for magnum loads. Jus like cast bullets, they are using an alloy harder than needed—maybe due to shipping and handling damage of very soft bullets.
You and your cases determine the proper expander diameter. Your cases should have an ID that is 0.001-0.002" less than bullet diameter. More will NOT give you more bullet tension—it will either expand the case or swage the bullet down—just as your are concerned about.
Thus, an expander for lead bullets, ideally, should be 0.001-0.002" larger than an expander for jacketed bullets of nominal diameter.
Fresh cases should have a soft annealed case mouth that has almost no spring-back. Work hardened cases will have more spring-back. Thus, old cases will need a larger expander to have the case retain the proper expansion.
In most situations, it doesn't matter for jacketed. For lead, any swaging down of the bullet diameter will destroy accuracy and lead to barrel leading.
Measure the case ID prior to expansion, the expander itself, and the case ID after expansion and see what you are getting.
Never saw any advantage to the M-die myself, and I have several.