Lyman M die question

1

1stmar

New member
For bolt action rifles i use the lee collet die for neck sizing and a redding body die. But for semi autos i use the standard sizing die with a plug. Question is, do you get enough neck tension w the am die that you can use it in a semi auto and not need to crimp? Also how does the runout compare to suzing w the lee?

Thanks
 
Question is, do you get enough neck tension w the am die that you can use it in a semi auto and not need to crimp? Also how does the runout compare to suzing w the lee?
Click to expand...
If you use a Lyman "M" die, you would likely want to "iron out" the flared portion of the case neck with the crimping feature of your dies. However, it begs the question, why are you using a Lyman "M" die in the first place? It is intended for cast lead bullets...is that what you are loading?

Also, as for runout, I have found that there is no way to predict how much runout you will have when using any brand of die. I had a set of RCBS .257 Roberts dies that would not produce a round with less than .017 of runout whereas none of my other RCBS dies produced anything near that far out of true.
 
I bought a Lyman "M" die a while back and was unhappy with the basic quality characteristics in it and used something else.
 
I ordered the Lyman M die for my 45ACP reloads , the bullet even with a flare wouldn't set on top perfectly straight and would sometimes create a bulge at the base of the bullet in the case on one side . Didn't cause a problem but wanted to stop it from happening . I'll see if he die corrects the problem .
I have been using the RCBS Carbide a set of 3 taper crimp dies , they worked well but didn't like the bulge . For rifle benchrest shooting I'm using the standard RCBS Full llength die with the comp. shellholder from Redding , works well for minimum sizing and the Comp. seating die from Redding .
 
1stMar,

With any expanded case you expect to use a taper crimp die on an auto-pistol cartridge to get the case mouth down to the tolerance range shown in the SAAMI drawing. What the M-die profile will do for you that a straight flare does not is let you set the bullets upright in the case so they seat straighter. You can see this by the bulge that mirrors the location of the base of the bullet being more uniform all around the case.


Dahermit,

The Lyman M die is being used by a lot of jacketed bullet loaders, too, but set to enter the case mouth far enough to form the small expanded step that precedes the flare-forming portion of the expander contour. No flare is made. The idea is to be able to set the bullet in the step so that it is straight upright as it enters the seating die. When you do that, the Lee and RCBS and Redding standard seating dies, among others, will usually produce significantly lower finished cartridge runout. With only the step impressed into the mouth, the step will fit a good many production chambers without being ironed out, and in those instances, it may be argued that it actually helps center the bullet in the chamber, you have to resize the case and check its fit in the chamber before relying on this to be true for you.
 
The Lyman "M" die is an open die body with an expander. It is made to flare the case mouth of bottle neck cases to allow seating cast bullets without shaving lead.

it does not seat or crimp bullets.

The amount of neck tension resulting from using the M die depends on user adjustment of the die. Given a normal relationship between your sizer die, expander ball, brass thickness, actual diameter of the bullet used, and expander AND seater die adjustments, the only way an M die affects neck tension (bullet pull) is that incorrect adjustment of the die can remove it.

In other words, if you flare the case mouth TOO MUCH, (and too deeply) it will reduce neck tension which you may not get back in the seater die.

Questions about M die's "runout" (concentricity of the loaded round) are irrelevant, the M die does not seat the bullet.
 
My bad shiuld have clarified this question is about rifle cartridges. A normal sizing die expander can impact concentricity. I use a lee collet die for bolts but it is not recommended for semis. Wondering if the m die is a viable option for semi autos and will provide adequate neck tension withkut deforming necks.
 
I was interpreting the OP's question to ask if using only the step portion of the profile (which you can do with jacketed bullets) meant you could escape the crimp step after the sebsequent seating. It can mean that in some chambers, but is not to be counted on, especially not if reliable feeding from a magazine is needed.

Runout is not irrelevant because using the step profile in the M-die profile results in the seating die starting the bullet into the case straight and without tilt. This means the seating die doesn't start the bullet into the case crooked. It really does reduce seated bullet tilt and therefore cartridge TIR significantly. Reduced runout is an artifact of synergy between the M-die and the seating die.

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That was my intent uncle nick. No second step expanding the cas mouth as that is not normally done in a rifle case and would require some sort of crimpto close the case mouth.
 
Questions about M die's "runout" (concentricity of the loaded round) are irrelevant, the M die does not seat the bullet.
Click to expand...

When you are doing assembly (cartridges) its a system.

So, while it does not seat the bullet, it gives the bullet a consistent place to seat without the yank of the expander ball on the sizer.

In the last 3 weeks I have shot 4 sub 1/4 (not by a lot) 5 shot groups.

I hate the yank on the sizer dies.

I love the smooth slickness of the M die (other than the round end its a straight wall)

I don't use the flare portion.

I use it for 3 x 30 cal cartridges with moving it up and down and a micrometer to set the depth right.

I have lube for the neck, combo of liquid and paste. I polish the cases when done with the process.
 
I ordered the Lyman M die for seating the 45ACP straighter on the case , when I receive the M die is the OD of the plug .451 or .452 lf that's the case would a M die let's say for a 308 be .308 to start leaving zero neck tension on the seating step ?
 
Before I got comp seating dies, used the Lyman m dies to help seat jacketed rifle bullets straighter. However was using a smaller caliber plug that didn't expand deep into the case neck, so the case neck tension was not decreased. If memory holds was doing this on .257 caliber rifle.

The pull through expanding plugs on rifle dies can be a serious detriment to accuracy. If your die set allows it, you can loosen the screw on the plug and allow the plug to self center on the case neck that was sized down. Also helpful is the carbide plugs that redding has that also "float".

Am not familiar with Hornady dies.
 
Zike: my experience has been with the 30-06, 308 and the 7.5 Swiss.

The length of the plug is long enough to reach to the bottom of the neck on all 3 of those without getting into the flare area (safe amount)

I change the setting to suit the difference with a micrometer keeping it well away from the flare so a bit over or under is not an issue.

I don't know enough about them to know if a .257 is not long enough.
 
RC20-To clarify what I meant was if I was reloading a 257 caliber, was using a smaller diameter .243 caliber plug. This only slightly belled the mouth of the brass, not expanding much of the neck, if at all. It has been awhile since I did this, but allowed flat based hunting bullet to be seated into the mouth of case. Was loading 257 wby at the time. and multiple partial seating while rotating was not meeting my needs.

I should have been clearer in the explanation :o
 
cw308,

When you show 0.451 or -.452, I am assuming you made the measurement with a caliper limited to that resolution. I know a lot of folks use calipers for this, but I think with bullet diameters and related measurements, like slug measurements, it is worth having a micrometer with a vernier scale for resolving tenths of a thousandth. They aren't expensive. CDCO Machinery has them starting at $17. With the vernier type, just check the reading at zero to subtract from your measurements. If you want to spend more money on an electronic digital one, Harbor Freight has one for $35 that will work well enough. The digital ones typically resolve half of a tenth of a thousandth (50 millionths). Not necessary for this application, as a fifth or even a third of a thousandth would be close enough with bullets, but it provides some pointless but pleasing degree of satisfaction to see all those decimal places.

Anyway, I am saying I'm not sure exactly what you have, but the step should be bigger than the bullet and the rest equal-to or smaller than the bullet. Equal-to works because the brass typically springs back 0.001" from expansion and that is enough to hold a bullet.


Real Gun,

That's a good resource you linked to. Thank you.
 
Unclenick
Thank you for the above post , the bullet I'm using with the Lyman M die expander is a 45ACP FMJ .451 from PrecisionDelta they feed an shoot good. I have the M die to position the bullet straight on the case , just finished cleaning the die , will load up some by the weekend . Thanks for all your help , I like the die .

Chris
 
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