Help! Need expander die advice.

[Andy45]

I'm trying to reload new .444 Marlin cases with jacketed bullets. I run the cases up into my expander die high enough to get plenty of belling for the bullets to fit. But when I seat the bullets, the cases do not expand concentrically / uniformly. Instead the cases stay flat on one side, and pooch out on the other. I also have this issue with new .38-55 brass. Suffice it to say, load accuracy could be better.

Should I carefully anneal the cases? Or should I buy some other type of expanders?

[Gtrubicon]

I’d look for a Lyman M die. They sure have made life easier for me.

[Chuck Perry]

Did you size the cases, or using them as new?

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[sparky45]

Haven't had a single problem with neck expansion on my 38-55 new brass. I ALWAYS use a Graphite lube on the case mouth/neck prior to using the 38-55 expander. I use Imperial Dry Neck Graphite Lube.

[popper]

RN bullet and improper seating stem. Standard 9mm problem too. Bullet doesn't go in straight.

[farmbif]

ive had same problem with 375 win, tried several things including different seating dies. the sliding feature of hornady seating die helps some.

[Three44s]

In my opinion a Lyman M die or the NOE version that installs in the Lee Universal expander die body would be my next move.

If that s not enough, a sliding seater stem such as farmbif just described would be the next try but keep the M type expansion/belling along with a slider seater.

Three44s

[skeettx]

Check your shell holder for dirt in the rim recess

[Taterhead]

You might want to look at whether the shank on the expander is sufficiently long so that it plunges to a depth into the neck that is deep enough to cover the length of the bearing surface.

Secondly, the diameter of the shank itself might be too narrow relative to the actual bullet diameter.

M profiles are irrelevant because they only affect the type of flair, and your issue is the neck interior diameter.

Here is an example to illustrate. Note that the standard plug is short so the bullet heel would seat into the part of the neck that hasn't been expanded. It is also too narrow for the bullet diameter.

The one on the left expands to the depth of the bullet bearing surface and leaves an interior diameter 1-2 thousands less than bullet diameter for perfect neck tension. These are RCBS M style plugs, but NOE might have a plug that will better fit your bullet.

https://i.postimg.cc/fyKWZxkZ/20180125-212015.jpg

[Andy45]

Thank you guys!

I liked the M did idea, but I think I'll try the NOE expander plugs first. Might be a more flexible option.

[Taterhead]

Thank you guys!

I liked the M did idea, but I think I'll try the NOE expander plugs first. Might be a more flexible option.

To clarify, NOE expanders are M style expanders. The defining characteristic being thr shape of the case mouth flair imparted. Ms make a cup instead of a bell.