Case mouth too narrow after resizing? Trim pilot too large?

[Rusty Shackleford]

New here and first post. I recently picked up a set of 3 die Lyman set for 5.7x28 (Lyman 7460486). After some messing around with Hornady one shot then switching to RCBS Case Lube-2, I managed to get them through the resizing process with minimal damage to the coating. After sizing I attempted to trim with an RCBS Trim Pro 2 however the .22 cal pilot would not fit in the case mouth. I took some measurements and think perhaps the resizing die is shrinking the case mouth too much. Would you contact Lyman about the dies?

Case mouth measured .213


Mandrel in die measures at .207


Pilot for the trimmer came in at just under .221 (no image)

[panzermk2]

I have never been impressed with the Lyman dies.

One shot should work just fine. You may have to polish the inside of your sizing die.

[Rusty Shackleford]

I don't think that will fix the case mouth sizing issue unfortunately. I put in an email to Lyman this morning.

[panzermk2]

For resizing CH4D is the best with Hornady coming in second.

You can also with CH4D you can order a custom sizer ball, but to the best of my memory I haven't seen an issue with the CH4D sizer ball.

All my Lyman for the 5.7x28mm was thrown into the scrap pile a long time ago.

[panzermk2]

Honestly I don't thing the sizer ball is the issue.

[panzermk2]

Something else is going on.

In that first pic, the shoulder of the case looks bumped out.

What brass is this?

[Rusty Shackleford]

Its FN brass. There isn't a "sizer ball" in the Lyman die I'm using just that knurled section which seems to be under sized at .207. My original photo didn't show it in the calipers just had the measurement shown with the part above.

[panzermk2]

In parlance it's referred to as a "Ball"

The knurled section is just there to aid in changing the de capper pin. It's NOT for resizing.

[Rusty Shackleford]

If you look at this photo above or read my previous post you would see that this die does not have a "sizing ball". This is a 3 die set and the only thing I can think is they intend you to use the neck expander die before trimming.

[panzermk2]

And it's supposed to, didn't you see my picture of the Lyman resizing die?

You are missing a part of your die.

[Buffman]

Lyman 5.7 dies are 3 die sets. The first die is for decapping and full lenth sizing only. The second die is for case mouth expansion, and the third is for seating. The decapping rod on the 5.7 does has no ability to expand the case mouth.

[panzermk2]

I have Lyman 2 die set that has the de cap and resize as the same die.

Hence the picture right from their website

If you are having issue with the mouth being to small, than why you relying on the de capper only and not using the second die>