How much belling of case mouth is too much?

[prs]

General consensus has it that our cast lead boolits need to fit not only the gun, but also the cases into which we press them. So the wise use an internal sizer correctly proportioned to open the case just enough more than common dies designed for J-words so as to avoid compressing the properly sized lead projectile. Lyman's M die and RCBS's Cowboy expander dies are popular examples and these also make a little "Dutchman's seat" right at the case mouth that is at full boolit diameter for about a mm or less in depth. For a bevel based boolit design, that seems to be plenty enough for me to start the boolit squarely; but for a flat based I still find that a little traditional flare helps.

Then, I noticed that when doing so, I not only did I avoid any scraping of lead from the boolit when seating, but I also eliminated scraping a little traditional NRA or other softer boolit lubes from the boolits' lube grooves. Even with bevel based boolits, lack of the flare would have me scraping just a tiny bit of lube from each round during seating resulting in eventual seating die lube packing. So, I just keep the dies set to do both, expand and create the Dutchman's seat at station 2, then set the powder through die to make a very small flare or bell at station 3. Cleaned my dies yesterday after quite a long time of neglect and thousands upon thousands of rounds loaded -- the seating die was absolutely CLEAN.

Then, to the point, I get to thinking; how much flare at case mouth is too much? At some point I would think the depth of the flare would be beyond that which the crimp die would correct. With 45 Colt and roll crimp or 45ACP and taper crimp, the Lee crimping dies I use seem to take care of my degree of flare and the M die's or Cowboy expansion die's extra seat. Have any of you run into the limitations of the crimp die to return a flare back to the desired case diameter?

prs

[462]

Doesn't using Lee's flaring die, after Lyman's M-die has created that very useful parallel seat, eliminate that seat and not allow the boolit to sit squarely in the case mouth?

Anyway, to answer your question. I use 11 different M-dies, both factory stock and custom made. The first step expands the case neck to no more than .002" under boolit diameter, and the second step is no more than .001" over boolit diameter. That gives the neck tension that I want and allows the boolit to enter the case without shaving lead or lube. Many years ago, the Lee flaring die started its appropriate role as a dust collector.

If you need custom M-die expander plugs, contact forum member Buckshot.

[jcwit]

I make my own, with sizes similar to what 462 suggests, maybe just a scooch bigger on the 2nd step, .0015. But that 2nd step only goes just below the case mouth by a few thousands, like .005.

[prs]

462, it would if you set the die too low, but if set so the expander just makes firm contact at end of stroke with the M die modified case mouths the operating tension of the powder dispenser is enough to make a slight flare just above what I call the Dutchman's seat. My M dies make that upper seat a slight friction fit to the sized boolit. The Buckshot powder through expanders tubes certainly sound like the bees' knees.

prs

[prs]

I make my own, with sizes similar to what 462 suggests, maybe just a scooch bigger on the 2nd step, .0015. But that 2nd step only goes just below the case mouth by a few thousands, like .005.

Your depth may be closer to reality; I said about 1mm, but prolly more on the order of .5mm or even a little less. "Just enough" is about right ;-)

prs

[bangerjim]

All my Lee 3-piece loading dies do the expanding with the powder-thru 2nd die. Where's the problem? (I know....people hate Lee stuff!) It is adjustable from no flare to HUGE!
Easy and simple to use.

For rifles I use the Lee universal expander which works for all cals and does a perfect job every time.

Using the above standard Lee inexpensive dies, I have NEVER shaved off any PC from ANY boolit!

banger

[pworley1]

I have been using the Lee universal expander ever since it came out. I have never had a problem with any cartridge loaded using it. I open the case just enough to start the bullet without shaving any lead.

[EDG]

No
The internal design of the dies I have used will crimp anything that you can run into the seating dies.
I have actually had over length cases flare larger than the internal diameter of the seater die.
The cases were just sized down slightly by the seater when forced in by the press.

"""Have any of you run into the limitations of the crimp die to return a flare back to the desired case diameter?"""

[Le Loup Solitaire]

Flaring is cold working he case mouth and he less of it you do the better. Of course it has to be minimally done to eliminate shaving, but it still cumulatively adds to shortening the case life...the same as crimping. LLS