Can someone explain the Lyman M die to me and how to use it with this setup

[TheGerman]

I have a Dillon 650 that I put a Mr BulletFeeder on. After setting everything up like I have a million times before, I start running the loading toolhead consisting of:

- Neck die (already FL size on the prep/trim toolhead)
- Powder
- Mr BulletFeeder dropper
- Seating Die
- Crimp

Almost right away I saw the bullets (55g FMJ, boat tails) rocking their way off the cases when they were dropped. A good 1/3 just flew off. I've done the whole smoothing the indexing 'upgrade' as well as got the springs and washers that help smooth the rotation of the plate; its not that, as I never have this issue otherwise.

Googling this, it seems to be a common thing with 223 and MrBulletFeeder. They even address it on their site and say you probably need a Lyman M die to open up the neck area for the bullet to sit itself inside the neck instead of riding on top of it and getting knocked off. I did a quick look at the M die and it seems like its just a 'one size fits all' mandrel for a single caliber; is this correct?

I'm assuming that you can use it to set the desired neck tension like I am doing with the neck sizing die in Station 1 just like with a mandrel, but here is where I get confused. How would you set the actual tension you want, and how does it do this in conjunction with flaring out the neck a little; wouldn't this cause run out, or how is this designed to work?

The directions I saw for the M die were very brief. It was basically screw it in until you get the amount of flare on the neck you want - well, its a rifle case, I dont wany ANY flare because again, doesn't this cause all sorts of neck tension inconsistencies and run out?

 

[Juma]

Great if you are using monolithic bullets to prevent shaving. Bells the case to let the projectile slide in. Use it with Barnes etc and ssm cleaning because you have no carbon. It prevents the galling between the inside of the neck and the projectile.

 

[MarinePMI]

Especially helpful on thin walled cases too (like 22 Hornet, 30-30, 32-40 etc.).

 

[TheGerman]

Ok, so how is it used/set up, primarily for 55g FMJ boat tails and how am I setting neck tension with it (there's no mandrel measurement like on individual expander mandrels you normally use) as well as is it supposed to flare the neck a bit, and does this cause runout?

 

[MarinePMI]

Just set it up similar to a pistol belling die. Just flare the lip of the case mouth to ease seating the bullet. Assuming you have enough bullet seated in the neck, concentricity issues shouldn't arise, since that will guide the bullet seating. Again, this assumes your FL or neck sizing die is not causing excessive run out (i.e the case neck is already straight before flaring it for bullet seating). Just adjust the die down until the case mouth is slightly flared (doesn't take much).

 

[Silverjay]

NOE makes a series of expander plugs that fit the lee version of the M die that are precision ground. I use the .226 x .222 one for 223. It gives a .226 bell with .002 neck tension.

 

[TheGerman]

NOE makes a series of expander plugs that fit the lee version of the M die that are precision ground. I use the .226 x .222 one for 223. It gives a .226 bell with .002 neck tension.

They dont happen to fit the Lyman do they

 

[Silverjay]

They do not, I switched from the M die to them because I have more diameter options.