Size dies. Something I hadn't realised

[Buckshot]

............I was doing some reloading in 7.62x54R for a M91/30 using the Nu-Judge 6 cavity boolit and jad sized some to .316". I had made a .316" lube die and then had to make a new 'M' die expander for that size. I got to wondering just what my Lee dies sized the caseneck down to, before it's getting dragged back over the caseneck expander spindle.

I took out the de-capper - expander and sized a case. With calipers the neck ID was .302"! Holy smoke but that's a LOT. I don't know if every make sizes that far down of not. The de-capper/neck expander then opens it back up to about .308". Then you normally expand/flare to seat a .312 to .314" slug. That is a bunch of sizing down and expanding back up.

Checking a fired case, the neck ID is right at .314". I chucked the die in the lathe and dialed the boring bar in .002" for .004" total just to see what that would do and where I needed to go. That made the caseneck ID go from .302" to about .307". I took off another .002" and now had caseneck ID's right at .312". Actually a smidge less but who's watching THAT close, eh?

Now the de-capper rod doesn't do anything other then de-cap as it doesn't touch the caseneck a-tall. While the die could stand to be opened a bit more it is a VAST improvement in metal working I mean going from about .314" down to .302" then back up to .308" and then we're expanding it AGAIN to .312" or so? Now it goes from .315" to about .312" only and then gets expanded (or really just flared) to take a .314 or .316" boolit.

..................Buckshot

[grumpy one]

Buckshot, you've done way more of this than I have so I'm just repeating things you already know. First, you want to end up expanding the case mouth after downsizing it because you need it to be sized from the inside, not the outside. That is one of the weaknesses of the Lee Loader: it only sizes from the outside, so the final case neck inside diameter depends on the case thickness at the neck, which varies from one case to another, from one brand of brass to another, and varies a whole lot if you form cases from some other caliber. The result is uneven case neck tension between different cases when you load a batch.

I've always thought the case sizing dies downsized so much more than necessary for two reasons. One is to make sure you end up with a uniform inside neck size, which can only be assured if every case goes through full plastic deformation at each step, shrinking as well as growing, in the same way as all the other cases. The other is that the sizing die can wear quite a lot before it will make any actual difference to the final size of the case after processing.

My guess would be if you measure some cases resized by unmodified dies (i.e. down to 0.302 then up to 0.313 in two stages) they will end up slightly tighter on the bullet than the ones that are only downsized to 0.312 then are hardly deformed at all by the M die. However it's a guess - I haven't tried it.

Of course even if I'm right, you might be completely satisfied with the amount of case neck tension you now get, even if it is a bit less than it was before.

[454PB]

I'm surprised you were able to machine the die with a boring bar. Everytime I've worked on a reloading die, it was too hard to cut with lathe tools.

[Catshooter]

With 7.62 brass as hard as it is to get, that's a damn helpful thing to know. Thanks.


Cat

[Buckshot]

I'm surprised you were able to machine the die with a boring bar. Everytime I've worked on a reloading die, it was too hard to cut with lathe tools.

............AH! Carbide my good man, carbide!



Grumpy One, you are correct and I hadn't actually thought of that. I have 500 rounds of Graf's headstamped brass, maybe 120 Norma cases and a hundred or so NNY (Serbian) cases. The Norma and NNY were given to me by a guy who'd sold a SVT40. The brass I'd used to check was Norma. I'll have to see what the Graf and NNY do in that die. Prolly should just get a Lee collet set anyway.

.............Buckshot

[45 2.1]

I don't know if LEE is offering correct collet dies for the 7.62x54R now, but i've used the 303 British collet dies with a washer over the case on top of the shell holder for years to neck size the Russian cases.

[gregg]

WOW. I wondered about that. I alway try to size a rimmed case so it head
spaces on the shoulder.
Now it i could stop over working the necks ?
I think you done good buckshot

[Larry Gibson]

I solved this 7.62x54 dilema a number of years ago as I have several M91s. There is considerable difference between them when fire formed. Alos the different rifles take different sized bullets, both jacketed and cast. As Buckshot discovered most all FL dies size the necks down enough to hold .308 bullets. I at first adjusted the FL die to size for the smallest chamber of the rifles I have. I found the FL die also resized the case bodies considerably and incipient case head speration happens after a few sizings/firings. Neck sizing was the way to go but instead of one neck size die that would size down for the smallest diameter bullet it occured that I could "taylor" the neck size with bushing dies. Trouble was no one made one. Measuring the largest fire formed 7.62x54 case I quickly noted that it as slightly smaller than a .284 Winchester.

I got a Redding Bushing die for the .284 Winchester and shortened it (easy with a lathe but it can be done with a grinder) so the shoulder of the smallest fire formed 7.62x54 casr just touched the die shoulder and the case stuck out the bottom enough for the shell holder to slip over the rim. The fire formed 7.62x54 cases are a nice slip fit in the die. I figured i could use a shim under the die locking ring to adjust for the longer fire formed cases (case head to shoulder) but ended up just adjusting the die for the longest cases and leaving it.

They beauty of this die is that with a series of bushings (.327 - .339 in .002" increments) I can size the necks down to however much neck tension is desired for bullets from .308 to .316". I also use the bushings in bushing dies of 7.62.39, .308 Winchester and '06 (also shorted to NS 7.65 Argie, .303 and 7.7 Jap) . Great versatility with bushing dies.

Larry Gibson

[stocker]

Buckshot: Try running a flared case into your seating die (short of any crimp shoulder that may exist) without seating a boolit. See if the seating die doesn't also remove the flare and size the neck down. I ran into this with a Lyman 32 Special seating die that gave me the fits with collapsed cases until I figured it out. The expander button I was using to seat the .323 boolits was opening the cases beyond the limits of the seating die which when used promptly reversed the neck sizing process. I wanted only minimal neck tension on the boolit with a crimp to ensure holding.

[swheeler]

Buckshot; looks like a good idea, should aleviate your need to anneal brass so often, the stuff isn't getting any cheaper!

[Carteach0]

Not having a lathe to play with, I had to go another path.
My LEE 7.62x54 sizing die does exactly what you have noticed, along with leaving nasty scratches on the case. Not having spare funds right now to buy a better quality die set, I had to make do.

So..... I took a fired steel 7.62x54 case and drilled the base. I installed a screw to allow the case to be chucked into a cordless drill. The case neck got coated with
valve grind compound and away we went! About 8 grinding sessions later, cleaning between each, ending up with 600 polishing compound....... I ended up with a sizer that still went down to .310".

I use my .303 British sizing die with the expander button set very far down to clear the die, and done as a seperate operation. This expands my case necks so they will grip a .313" bullet nicely.

I also found the LEE seating die to be the worst one I have ever had from LEE.
It had sharp internal edges that would grip a cast bullet nose and yank it right out of the case. So much for consistant seating! I had to tear the die down and reshape the seater stem. Doing so I looked the way the die works... No way in hades that thing is going to seat a bullet straight.

Guess I need to break down and buy some decent dies for my Mosins....