Lyman "M" die

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  • Last Post 13 December 2013
Longone posted this 08 December 2013

I am going to branch out to casting and loading for a 7mm with a relatively short cartridge 1.7” OAL. My question is will a Lyman “M” die work for that length cartridge? They are listed on the Lyman site as working for 7x57, 7 Mag which are considerably longer. I have been a RCBS expander user till now but the dealer that I buy all my reloading/ casting stuff from is out of the RCBS 7mm expander and I thought this might be a good opportunity to try the “M” die.

Longone

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Shadowdog posted this 08 December 2013

Short answer...Yes, with the normal adjustments in set up it will work fine for the 7X57 Mauser.

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joeb33050 posted this 08 December 2013

When I was loading the 7mm TCU, the normal 7mm m die was too long. die bodies come in long and short. All expanders fit any body. I have a 7mm expander that I'd be happy to send, no short bodies though

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highstandard40 posted this 08 December 2013

Not only are there short and long die bodies, there are also different length stems. I have several “M” dies and I often have to swap combinations of die body,stem, and of course expander, to hit the right combination.

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Longone posted this 08 December 2013

Can a short body be ordered separately? And if so where can I find one?

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John Alexander posted this 08 December 2013

Read my article in the July/August 2012 Fouling Shot for how to never buy another M die or worry about long bodies and short bodies again.

You can easily achieve similar but better results, make your brass last for at least 150 reloads, and save time reloading.

The M die should be obsolete like film cameras and VHS tapes and In my opinion is only surviving on momentum and habit.

I know this sounds like somebody trying to sell something (which it isn't) or a politician running for congress but read the article before you pass judgement.

John

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onondaga posted this 08 December 2013

http://www.castbulletassoc.org/view_user.php?id=6699>Longone

A little ingenuity and elbow grease with a hunk of metal, a caliper and Lee Universal Neck Expander Die that is a  case mouth flaring only die and you can use an electric hand drill or drill press to turn a  plug for the Lee die to custom expand and case mouth flare your brass to just the size you want. With your custom plug, you can get both steps of the job done just like the Lyman “M” die does. Make your new plug right and it will self center like the original expander only plug for the Lee die does. You can even modify one of the original plugs in the set that comes with the Lee Universal Neck Expander Die to do this. The Lee Universal Neck Expander Die is on sale for $11.99 at:

http://www.midwayusa.com/product/140461/lee-universal-neck-expanding-die>http://www.midwayusa.com/product/140461/lee-universal-neck-expanding-die

Gary

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Loren Barber posted this 08 December 2013

I'm slightly puzzled by the need for an M die. I presume the goal is to flare the neck so that shaving lead off the bullet is avoided. For several years now, I have used a VLD chamfer tool to slightly bevel the inside case neck. I think it works about as well as any technique that I've tried. I hope that I haven't misunderstood your objective. Loren

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highstandard40 posted this 08 December 2013

The desired ideal case neck prep goes beyond just a flare to accept a cast bullet. Case neck tension should also be considered. I use custom expanders to give between .0015” and .002” bullet pull on bottleneck cases. Factory case neck expander balls are designed for jacketed bullets. My custom 7mm expander that I use for cast bullets is about .002” larger than the factory expander. The ideal situation is to use sizer dies with the neck bushing setup. This allows for proper case neck tension for cast bullets without overworking the brass.

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onondaga posted this 08 December 2013

http://www.castbulletassoc.org/view_user.php?id=7887>Loren Barber

You have really missed the point. The bigger function of the “M” Die or a custom neck expander die is expansion of the neck inside diameter to a size that does not swage down the diameter of cast bullets and make the bullets undersize. Yes, the case mouth flare aids in bullet seating but the neck expansion is much more important to accuracy with cast bullets. This important step is one that is frequently ignored by newcomers and ignoring this step when needed to keep bullets large enough  so there is no gas jetting is the most  common problem that makes cast bullets shoot all over the place and discourage beginners by making them believe accuracy with cast bullets is a myth.

Bullet fit to the throat of firearms chambers is the primary factor in accuracy with cast bullets. Ignore that and you will have poor accuracy with bullets shooting all over the place and leading up of your barrels too. Well made and good fitting cast loads shoot as well as or better than jacketed factory ammo when you get it right.

Gary

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Tom Acheson posted this 08 December 2013

Agree with use of the bushing style die approach to optimize neck tension, bullet pull, etc. Have had good results using a Sinclair neck turning “spud” to open the case mouth and then play with different sized bushings to bring it back down to the best neck ID/cast bullet OD that gives the best results.

Tom

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LWesthoff posted this 08 December 2013

I mainly load for '06, .308 and 30-40 Krag, and since I shoot competitively, I load quite a bit. Since I discovered the Lee collet type neck sizers, I have not looked back. No more M dies. I much prefer using that Lee tool, and case necks just about last forever. I'm not real fond of a lot of the Lee tools, but I think the collet type neck sizer is about the best idea Mr. Lee ever had.

Wes

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Longone posted this 08 December 2013

I would love to use a bushing die to control neck tension, but because this is a bit of a wildcat it might be a problem. Although I do wonder if I could set up a Wilson die with the proper size bushing and just run the case in that to size the neck? I have a set for the 6BR that I might be able to swap out the bushing. Whadda ya think, will that work? I realize the case won't go fully into the die but will that matter?

I'll go look at the Lee.

Longone

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Loren Barber posted this 08 December 2013

I already assumed all of that about neck tension etc etc etc

to me, an m die is a neck flaring tool. RCBS may make custom diameters with a flaring shape. I own three different diameters for 30 caliber from RCBS. I'm not sure what would be the preferred ID of case neck for 7mm, but I have a 7 mm neck expander from Sinclair International that measures 0.282. This particular accessories is used to expand 6 BR cases to either 7 BR or 30BR in stepwise fashion. Lots of tools to try.

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Loren Barber posted this 08 December 2013

What is your preferred ID diameter?

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Tom Acheson posted this 08 December 2013

I too looked at the Lee site but their info says that their collet concept is not recommended for lever actions, which is what my current project is.

Tom

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R. Dupraz posted this 08 December 2013

John:

So, enlighten us on your magical formula, My July/August issue happens to be missing.

RD

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onondaga posted this 08 December 2013

http://www.castbulletassoc.org/view_user.php?id=281>Tom Acheson

Lee Collet Neck Sizing Die for a lever action is a gamble. If your fire formed, then Collet Neck Sized brass, and your loaded ammo from it  functions well through your lever action, then you are fine. However, fire formed brass body size does not always function well in a lever gun with neck sizing only. If you try it and it works, go with it.

My first recommendation with a lever gun is FL resizing with a custom  size expander bell that gets your case necks .001” smaller than the correct throat fitting sized cast bullets for your rifle. An expander bell/DE-cap pin for a .303 Brit with the top shortened to the length of the original overall length of your previous one usually does it for most 30 cal lever guns. You can swap expander bell/ De-cap pins in Lee FL dies or Lee will custom turn one to your specification for a fee.

I also recommend a chamber casting to get an accurate throat measurement and then do what you have to do to get your un-lubed bullets to match throat dimension. With a fit of the bullet to the throat, the ball seat/ leade will size your bullets into the rifling perfectly as you shoot for the best accuracy of your rifle.

Gary

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Tom Acheson posted this 08 December 2013

Gary,

Thanks!

Appreciate the die box and lever gun suggestions.

Am working with a Marlin 336 chambered in .38-55. Have some test loads put together but it is way too cold to be tempted to get out and shoot. After those rounds are cycled through I'll closer at your suggestions.

Tom

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joeb33050 posted this 09 December 2013

I use Lyman M dies and like them a lot. The “belling” of the case mouth isn't needed for gas checked cast bullets, at least for mine. They go in fine. The M die works as an inspection tool, allowing me to feel big variation in pressure required. Little pressure and out goes the case, frequently little pressure means a split neck. The M die is set to bell the case neck so the mouth drags on the chamber. Belling the case mouth so makes it seal and keeps gas from blowing back, getting cases dirty and denting necks.
In 2003 I bought Lee collet dies for .223 and .308. After trying to make them work and reducing rod size and destroying cases, I gave up. Realizing that everyone else had great luck with Lee collet dies, I bought them again for the same cartridges. And after valiant efforts, I can't make them work again. They're on the shelf, I use Lee loaders or RCBS/Lyman dies and M dies without trouble. I don't know why, but the collet dies size necks to widely varying tension/size? It must be me.

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R. Dupraz posted this 09 December 2013

No Joe, it's not just you.

My Lee collet dies are also on the shelf for the same reasons. But mostly, I found that I get more case neck run out with the Lee collet die than with a good straight full length or neck sizer. When they are set up right of course. In addition, I anneal my cases periodically and the Lee collets leave fairly deep creases in the case necks.

And, I do use the Lyman M-Dies as well. In my experience, I have found that the above, amoung some other things, results in the best loaded round concentricity of anything else that I have tried.

RD

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