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Discussion Starter · #1 ·
This mourning is my first time using a Lyman M die on some new 444 brass. They look really weird coming out of that die really bulged out but .432 dia. bullets seem to fit into case pretty good. Just putting them in with fingers. With oversize bullets are they just going to look that way. I would hate to screw up some 444 brass as its now made of unobtainium. This question may sound dumb but the only dumb question is the one you don't ask. I have only loaded jacketed bullets before and didn't use M die. And I have several M dies now 30-30 .32 .35 .444.
 

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There should be some resistance to inserting the bullet. And you still need to crimp them unless you're shooting them one at a time. And just enough bell to the case to get the bullet started.

If you think it's expanding the case too much, measure the expander. I use the M die for 45 70 and I like it.
 

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If it bells the case mouth to much adjust your die, the case only needs a very slight bell, at best!
 

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I haven't tried the .444 "M" die yet but have both long and short 30 cal and they work great.
 

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Discussion Starter · #5 ·
Its not the very end bell adjustment that worries me its where the leading part of expander plug expands interior of brass before it hits the bell adjustment part of M die.
 

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Its not the very end bell adjustment that worries me its where the leading part of expander plug expands interior of brass before it hits the bell adjustment part of M die.
I guess I'm at a loss as to what is wrong, the job of the "M" is to keep a straighter, larger, longer form inside the case and put a slight bell on the case. If you have the die adjusted right, you will not feel the belling part on the stroke of the press.
 

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Discussion Starter · #7 ·
M die

I guess I was having a senior moment that lasted a while. After taking apart M die I could see how the thing works. Just have to have die set shallow on press and have brass enter slightly into die. Instructions were pretty much useless. Thanks Starbow for setting me on the right path.
 

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Unlike traditional expander dies, the M die is only designed to expand to bullet diameter (or just under). It isn't supposed to put a 'bell' on the case mouth.
Although Mike G has offered some advice on "improvements" to the M dies, on the Beartooth Bullets website, the first image in his article is useful for understanding how they work.
"M"-Provements On Lyman's "M" Die.
Unless you modify your expander plug to have a tapered profile after the full diameter step, the case should never go past that second step (.430-.432"). Doing so causes a 'hard stop' that bulges brass, until you apply enough pressure for the mouth to radically expand, or crack and tear.

I don't know if it's even mentioned in the article I linked, but you should also make sure you have the correct die body. The full length M die body is marked "M1", and the shorter body is marked "M2".
With a .44 caliber expander plug (standard plugs are marked "44MP"), the M1 body is preferable for .444 Marlin, while the M2 body is preferable for .44 Mag. (The adjustment stem is the same, for both bodies.)
 

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Unlike traditional expander dies, the M die is only designed to expand to bullet diameter (or just under). It isn't supposed to put a 'bell' on the case mouth.
Although Mike G has offered some advice on "improvements" to the M dies, on the Beartooth Bullets website, the first image in his article is useful for understanding how they work.
"M"-Provements On Lyman's "M" Die.
Unless you modify your expander plug to have a tapered profile after the full diameter step, the case should never go past that second step (.430-.432"). Doing so causes a 'hard stop' that bulges brass, until you apply enough pressure for the mouth to radically expand, or crack and tear.

I don't know if it's even mentioned in the article I linked, but you should also make sure you have the correct die body. The full length M die body is marked "M1", and the shorter body is marked "M2".
With a .44 caliber expander plug (standard plugs are marked "44MP"), the M1 body is preferable for .444 Marlin, while the M2 body is preferable for .44 Mag. (The adjustment stem is the same, for both bodies.)
Good to know! Thanks for the information.
 
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If it bells the case mouth to much adjust your die, the case only needs a very slight bell, at best!
The M die is in my experience very touchy on the depth and it will bell the mouth so bad as to make it useless.
As a matter of fact the standard "plug" that expands the case is factory spec to .430. To get it to expand to cast diameter you need to buy a custom die insert.
There's a guy on CastBoolits that can make you one for a very reasonable price.
Honestly I've gone to *not* sizing my cases and using the standard Lee neck expander as it has a better adjustment.

PS: Hadn't got to FrankenMausers post yet - he got it 'zactly right.
 
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