Setting Lyman M dies

[J. D. R]

So I am a long time Lee die user until recently when I bought a former commercial loading company's remaining inventory in Florida and walked away with dies of every make and dillon reloading presses galore.

In the mix is a M die for 30 cal, 223, 38/357, 44 mag, 45 acp, 9mm.

I sat down and screwed the m die body until it almost touched the shell plate of my dillon rl1000 and proceeded to screw the stem in until it stopped on the case mouth. I proceeded to gradually turn the stem until I was able to set a bullet on top of the case and it slide into the case squarely with minimal force.

How does this set up compare to yours as users of such dies?

I am very pleased as this die let's me seat a bullet and not worry about if I set it on straight.

[sigep1764]

You got it just right. Set it deep enough that it doesn't swage the base of the boolit down and load thousands.

[ReloaderFred]

That's the correct way to set up the Lyman M Die. I really like them.

Hope this helps.

Fred

[avogunner]

As others have replied, yep that's the correct way to set up the 'M' die. One more hint though, I use a fired case for the initial adjustment of the stem. With the fired (non-sized) case, you can quickly qet to, and easily feel, the expansion step. Then I just fine tune with the intended cases to be expanded.
Semper Fi

[Three44s]

avogunner,

That “fired case” technique is interesting and should save a bunch of time!

I will try that next time.

Thanks

Three44s

[cwlongshot]

Know that the M-Die is NOT a regular flair die. It creates a "pocket" for the bullet. This allows proper a d square bullet seating.

First of all very important that the cases are trimmed to same length. Then do what you have done BUT keep turning the stem in until you do get a flair but EVER SO SLIGHT flair.

The site wont allow my pics to show/explain better..

CW

[J. D. R]

I loaded 100ish 38 specials to start out with and all chambered properly in my Smith and wesson 36.

The brass I used was mixed and was as old as 1964 military surplus to gfl I picked up at our local range last year, so case length was certain to vary.

I did not notice any issues setting the bullets, do I have to trim pistol brass in order to use a m die?

[ReloaderFred]

I NEVER trim pistol/handgun brass. Life is way too short for that. I currently load between 8,000 and 10,000 rounds of .38 Special per year for our SASS matches, and the thought of trimming even one of them gives me chills. Of the 35 calibers I currently load, 15 of them are handgun calibers, and they don't get trimmed.

Rifle brass gets trimmed every time (except for the .38 Special for the Marlins), since they stretch, and we don't shoot nearly as much in rifle calibers.

Hope this helps.

Fred

[Three44s]

I NEVER trim pistol/handgun brass. Life is way too short for that. I currently load between 8,000 and 10,000 rounds of .38 Special per year for our SASS matches, and the thought of trimming even one of them gives me chills. Of the 35 calibers I currently load, 15 of them are handgun calibers, and they don't get trimmed.

Rifle brass gets trimmed every time (except for the .38 Special for the Marlins), since they stretch, and we don't shoot nearly as much in rifle calibers.

Hope this helps.

Fred

I respectfully disagree

I trim, everything ...... once right at the beginning ..... except for auto loading guns with straight walled cases. Those get measured and sorted to a maybe trim of over spec cases, which is rare. Crimping those involves a taper crimp and small length variations is not much of an issue.

But back to rimmed revolver brass (subject here). I trim those once and mainly forget about them for quite a while as growth is very slow. Typically you roll crimp these rounds and between belling and crimping I want consistency.

Straight walled rifle ..... same.

The premise here is not a specific length but that they are growing together, I watch for max length exceedance but in those straight walled cases, it’s more like watching paint dry and that’s good.

Bottle necked rifle and pistol, once and done for quite a while, generally. Hotter rounds and more full length sizing demands closer attention but I have never needed to trim every firing with anything so worst case scenario, monitor the case growth.

Most of my rifle rounds are fired out of bolt guns and are also varmint cartridges, thus I generally use a Lee collet die or other neck sizer and case growth is minimal there as well.

It’s the boomers like my 25-06, 7 mm Rem Mag and 300 RUM where growth stacks up more and that are more typically FL sized regularly.

Three44s

[cwlongshot]

Your "accept" is what Fred is referring to Three4's

While I do agree trimming straight wall pistol brass is almost a futile affair... My point was for the M-Die to function as intended it needs uniform case lengths.

I added a LEE hand trimmer to my case prep station making this step quick and easy. While not used for bottle neck rifle (altho would work fine) I use this for my pistol cases, That need prep. (No not all)

To answer your question J.D.R. NO, but it makes it work better. The die cannot make the same "flair" when case lengths differ.

CW

[Walks]

I agree that trimming handgun brass is generally a waste of time.
For light loads. I loaded .38Spl, .44Spl, .45Colt and .44WCF for 20+yes of Cowboy Shooting.
Upwards of 20,000rds a year. Starting out with all new or once-fired brass I never worried about it. A Taper Crimp doesn't require a same case length.
But the .44WCF did require case trimming for 2 reasons; it's a "semi-bottleneck" case and you need a proper Roll Crimp to lock the bullet into the case for use in a Lever Action rifle.

The other reason to trim straight handgun brass; Hot Loads, Really HOT Loads.
As in the .454Casull, I learned Very early on that Freedom Arms Revolvers are made with Extremely tight tolerances. All brass had to be trimmed to minimum and bullets crimped at the Very Top of the crimping groove. There was not enough room in the cylinder for a cartridge to exceed minimum O.A.L. it would stick out the chamber mouth and tie up on the forcing cone.

And it can help in accuracy testing. Same case length means same crimp tension, and neck tension too. That neck tension is something the Lyman M-Die really Shines at.

[MostlyLeverGuns]

I set the 'M' die so that the the bullet base/gas check seats into the case neck enough to stay upright in the loading block, this also works in the progressive to assist straight bullet seating. For cartridges that do not require a crimp to function, light handgun loads, single shot/box magazine rifle I may just touch the case mouth with the crimp die to eliminate the little 'flare' that may exist. TO ME using the 'M' die and NOT crimping reduces any need for case trimming as the bullet pull will be same regardless of case length, with the actual bullet contact surface the same length for all. I am talking about case lengths that are reasonably uniform +/- .006. Like many have said I don't usually trim handgun cases

[Three44s]

My point is trimming straight walled revolver brass is far from a waste of time and that the slow growth upon subsequent firings is an advantage to a once and done trim, not a reason to not trim.

While one can get away with various length brass with light loads, I find that belling (Lyman M die included) for cast boolits and decent roll crimping both demand consistent case length.

One trim and many subsequent firings yielding good belling and better crimps is worth it, IMO.

Three44s

[cwlongshot]

Agreed!!

[PhilC]

As others have replied, yep that's the correct way to set up the 'M' die. One more hint though, I use a fired case for the initial adjustment of the stem. With the fired (non-sized) case, you can quickly qet to, and easily feel, the expansion step. Then I just fine tune with the intended cases to be expanded.

Nice tip!