Lyman rifle neck expanding M die -- is it also an FL die?

[22_boomer]

I have several rifles that I use with lead and one is a 45-70. I was just told that Lyman has a neck expander die with a little extra piece at the top of the expander that will bell the case mouth so I don't have any problems seating my bullets. What I wanted to know is the Lyman RIFLE NECK EXPANDING M DIE also a full length sizing die or do I have to full length size the fired brass then use this to make the neck perfect and also expand the case mouth? Right now I FL size all my brass then use a Lee case mouth expander to bell the mouth so the bullets are seated easy. A friend is also interested since he wants to use Hornady FTX bullets that requires the 45-70 brass to be shortened.







ftx

[earlmck]

No. It just does a really nice job of neck-expanding/belling the case after you have sized.

[1hole]

M expanders are single function tools; they expand.

[ReloaderFred]

A case mouth expansion die can't also be a full length sizing die, as the sizing operation would iron back down any case mouth expansion imparted at the top of the stroke when the brass is extracted from the die. It's a two step operation, sizing, then case mouth expanding. The Lyman M Die is perfect for what the OP wants to accomplish.

Hope this helps.

Fred

[LouB]

Reloaderfred hit the nail on the head. You resize with the sizing die, then use the expander die to widen the mouth to accept the bullet w/o shaving it. So how could the sizing die narrow the case, then internally open the mouth, followed by withdrawing the case from the die, which would send the brass back thru the sizing die mouth, resizing the case again.

LouB

[ukrifleman]

As previously stated, full length size first then use the M die to expand and flare the case neck.
ukrifleman

[Taterhead]

Very good info above, and here is a bit more info to expand on it (pun completely intended).

Regular FL and neck sizing dies necessarily size the outside of the neck diameter a little too small. That is because the die maker does not know the thickness of the brass in the necks and must size sufficiently to cover the full spectrum of variation.

Unless the thickness of the neck is uniform, that means that the sizer also makes the outside diameter round, but the interior is out of round. The expander then does two things, whether an M style or expander button ins the sizing die.

1) makes the interior diameter of the neck round, and
2) sets the interior diameter to a uniform size that is designed to provide appropriate neck tension (this is variable depending on bullet diameter). Most expanders in die sets are configured for nominal jacketed diameters.

The M expanders optionally will give a touch of case mouth flair to facilitate bullet seating.

[uscra112]

Generally speaking, M dies expand to the correct internal diameter for cast bullets, which may be too loose for jacketed unless they are going to be crimped into an appropriate cannelure.

If the O.P.'s friend is loading jacketed bullets, he's already doing it correctly - size, then slightly bell the case mouth to ease seating of the bullet.

Finally, Lyman only makes expander plugs for their M dies in a few diameters, which may not be correct for your cast bullet if it is for any reason larger or smaller than nominal. Look to some of the aftermarket suppliers for non-standard plugs if your application needs one. Or make your own of you have a lathe.