Expanding or M dies for cast bullets

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Dec 30, 2002
Mr. Jefferson's country
Has anyone used the Lee cast bullet expanding die, or the Lyman M dies for cast bullets?
Are they more effective than standard expander die belling for loading slightly oversized cast bullets?
Cast bullets in my .45 are shaving lead up to the case mouth. This is having the effect of increasing headspace just enough to chamber a round so that the striker will fall, but not enough that it will fully hit the primers. I'm getting light strikes like crazy. This has happened on an erratic basis with 2 brands of commerical cast bullets,and also with my own cast bullets. I'm getting a sizer set to swage down any oversize bullets,but was wondering if the expanding die is also worth it.
Funny you should ask. I'm curious, too -- there is a write-up on .45 Colt loads on the realguns.com site that strongly suggests using the Lyman M, so I bought one but have not yet tried it. My experiences with cast bullets in .45 and .454 cases suggests that it might be a real boon. I'll be interested to see replies on this. I haven't gotten around to loading any cases with the M die yet myself, but it seemed a modest investment (or gamble?).
Yeah, I use an "M" die when loading cast bullets for rifles. I have a .30 Long, .30 Short, and 8mm M dies.
When loading a cast bullet you need to bell the case mouth to prevent shaving lead when seating the bullet. When loading jacketed rifle bullets you don't bell the case mouth and most (all ?) rifle die sets don't contain any die to bell the case mouth. So, for cast loads I bought the M die.
For handguns, I am not sure what this would accomplish that a standard die set doesn't already do. You already have a die that bells the case mouth.
For handguns, I am not sure what this would accomplish that a standard die set doesn't already do. You already have a die that bells the case mouth.
See, that's what I'm wondering. Why bother unless it performs some special operation that normal belling does not? I assumed that it must actually perform a "deeper belling" of some sort-not so much flare at the case mouth, but expansion further into the case perhaps.
If they're solely for necked cartridges,than I have no need for one.
Poodle shooter,
the m die expands the case further down and doesnt over expand the top as much, gets a lead bullet in much better.
The real Lyman M die expands the case neck to give normal bullet tension and then expands the very mouth into a step instead of a flare. It is easy to start a bullet, cast, gas check, or jacketed straight for seating. I use them for all rifle loading except bulk .223 hardball. There are flaring dies like a pistol expander masquerading as M dies. They work fairly well but I like the real M better.

For loading oversize commercial cast bullets, I think a sufficient plain flare would do. The M die does not make a real large step, and if your bullets are that oversize it might not help.
I have always used the "M" dies in all my pistol reloading as almost all of it is cast. I bought a set of Hornaday dies for my 9mm and tried using their expander die with cast and imo it is too abrupt for cast. The flair was too short and I shaved lead, I put a Lyman 9MM "m" die in place of it and no problems with lead shavings. All you need is 1 "M" die and you can get individual caliber ends for a couple bucks apeice from Lyman. Nick
Are you using a 3-die set,which seats and crimps in one die?If so,seat and crimp seperately and the problem will go away.Adds some time unless you have an empty spot on a progressive or turret,but well worth the time,IMHO.I would never go back to 3-die sets.They shave material and gum up worse than 4-die setups.be sure to get the die that crimps for your caliber....taper crimp for acp,roll for 45colt(aka long colt.
Are you using a 3-die set
No, I'm using 4 dies in a single stage. I seat and then use a Lee factory crimp die as a seperate operation. My key problem is that many of my bullets are cast oversized (even factory cast bullets). Even with my case mouth belling set as wide as I can make it, it still shaves lead from any bullet over .452". The only short term solution till my sizing kit gets here is to seat below the bullet shoulder,and manually trim the excess. Testing last night revealed that even seating as short as 1.150 proved insufficient as lead was still pushed up by the lower case wall portion of the massively flared case
I think I'll work with the sizing issue first, then get an M die if resizing doesn't work.
So basically, the Lee die is just another flare die, whereas the M die actually does expand the deeper portions of the case.
thanks guys
Another note for ya--it's a very good idea to make sure all your lead-bullet cases have been lightly chamfered at the mouth. Once-fired factory brass often keeps a little inward "lip" there even after belling, which can act like a little knife-edge on the bearing surface of your bullets unless you really GRIND on the belling. Just never chamfer more than half of the front edge of the mouth away, or your crimps will be nice looking on the outside and not much grip on the inside.
Hey folks,

Grump mentioned chamfering the case mouth to facilitate the loading of cast bullets. I started casting 30 caliber bullets nearly forty years ago for a 30-40 Krag, and I had read Lyman's manuals which suggested an "M" die was necessary for use with rifle cases. A friend of mine suggested I try chamfering the rifle case mouths before buying an "M" die to expand the mouth. I found it worked perfectly for my Krag cases. Since that time, I have simply chamfered my rifle case mouths and have never found any rifle cases which required the use of an "M" die for my cast bullets.

Best wishes,
Dave Wile
I like the powder-through belling doohicky that Lee`s auto disk system uses. It bells the neck nicely, and throws a powder charge accurately at the same time, too!
"the m die expands the case further down and doesnt over expand the top as much, gets a lead bullet in much better."
Being the user of 2 "M" dies in .30 long and 8mm, I think Randall has it right. I have never used an "M" die for pistol cartridges, but seat the bullet before final crimp. Quantrill
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