Case sizing question

Intheshop

Banned
Purely hypothetical..... not that I'm opposed to trying it,just don't have any dies that are "disposable".

Take a std chambering.... we'll say a 308....

If you,"nicely" lathe turned off .050" from the bttm of a sizing die,and then ran a case up in it,would that .050" "show up" as an increase in neck length?

NOT suggesting a dang thing,fully realizing a die blank and a custom reamer would be the proper way to make,whatever dimensions.... and,the need/importance of chamber vs sizing die specs.

Just curious what y'all thought would happen "to the case" (not how it would fit an existing chamber OR,how much sense it makes)....where would the brass flow to?
 

KeithB

Resident Half Fast Machinist
Well. since you would be pushing the shoulder back the shoulder-to-neck length would definitely increase. Would the reduction in the diameter for a small length cause the displaced brass to flow forward to increase the overall length? Maybe, or maybe it would just push the brass down and make it a little thicker in the body. Hard to guess, I would want real data from an experiment of some sort. Seems to me that my experience with normal sizing only lengthens the neck when an expander ball is drug backwards on the reverse stroke.
 

Brad

Benevolent Overlord and site owner
Staff member
You would move the shoulder back. Would you get .050 longer in the neck? Possibly?
Brass springback would play a role in how long the neck became.
I would not want to use die length as a gauge, I would want to measure off the datum line on the shoulder to know how much shoulder moved back.
 

RicinYakima

High Steppes of Eastern Washington
Having done this very thing to make dies for the wildcat 30 Johnson and make 7mm Mauser cases from 30/06, there are two variables; lube used and brand of die. If there are no obstructions on the upper part of the die and the decapping stem and top of the die are removed, the brass just flows upward the same size as the neck opening in the die. If using a good case forming lube, like Imperial sizing die wax, and rotate the case every 1/4 inch, it is easy to do. If using spray on or poor lube, the case collapses. HTH
 

Ian

Notorious member
Brass "draws", meaning stretches, it doesn't "scrunch up" and get thick when you push the shoulder back. The displaced brass goes up the neck, lengthening it.

The challenge to making a useful neck after you draw the shoulder back is twofold: Getting rid of the crease at the neck-shoulder junction, and getting rid of any "donut" formed by the original neck-shoulder junction or from brass flow from firing a time or two. The ring that forms in the neck is harder to get rid of than you might think, even when annealing the shoulder and doing multiple sizing operations with the expanding ball in place.
 

S Mac

Sept. 10, 2021 Steve left us. You are missed.
The only thing that I can add here is if you do move the body, shoulder juncture there is a good chance that the case will split at the old juncture. Forming 7x30 Waters I have had that occur several times.
 

Intheshop

Banned
Very good stuff fellas....

Is it a fair comparison,from a "drawing" standpoint like, running say a 7X57 case up into a 7-08 die?

Which came to me whilst walking this morning....wasn't thinking this initially.
 

Wallyl

Active Member
Had an "issue" with sizing 9mm Luger brass w/ a Lyman carbide sizer die. Some cases would come out with a belt. I fixed the issue by adjusting the sizing depth in the die to size just enough so that it would easily chamber.

10561
 

fiver

Well-Known Member
the XCB round is a 30-06 with .25 cut off it.
the idea was to be able to size X57 cases in the x57 case length die,, and flow the cases forward slightly to make up for them being a touch short.
it pretty much worked like that except when you fired the round the case shortened back about .005.
leaving you right where you started, only now with fire formed cases you didn't want to start mushing again.

anyway brass will flow forward it just doesn't always end up where you think it will.
if you want longer cases you have to start with longer brass for the best results and account for the movement when you fire it.
 

Rick H

Well-Known Member
The only thing that I can add here is if you do move the body, shoulder juncture there is a good chance that the case will split at the old juncture. Forming 7x30 Waters I have had that occur several times.


Did your cases split in fire forming? That has not been a problem for me fireforming 7x30 Waters from 30/30.
 

popper

Well-Known Member
You want the answer? Full length size a fired 308W case but drop the expander ball into the case on extraction. Get your really good high precision ball mike out and check neck thickness. Surprise! All the sizing force is down toward the base until the ball pulls up through the neck. But by then the moved metal is a donut at the shoulder. And if you don't anneal the shoulder area (like Mil does) you can get shoulder failure.
 

Jeff H

NW Ohio
First, sorry for not having contributed anything in a while. Just hectic "life stuff." I still appreciate the wisdom and camaraderie here.

If this helps at all:

In the mid-eighties, guys who felt the 6.5x55 brass was "odd," started cutting their sizing dies short, had barrels set back a commensurate distance and ran 308w brass into those shortened dies. Hmmmm, the 6.5 CM isn't new? These were loaded to 6.5x55 pressure levels. Might be urban legend. I wasn't in on this. Couldn't see putting that kind of money into a (near pristine) $89 Swedish military rifle.:oops:

Twenty or more years ago, my dad "invented" a new round by shortening '06 brass to 57mm and seating .308" bullets in it. In his world, that was "new," so I watched and enjoyed seeing him enjoy himself.

Fairly recently, I was working on 222 loads and found a small odd lot (3) of 5.56 cases, looked at the 222 FLR die and thought "hmmmmm?" Action, from which an unknown result would come followed, and I now have three strange-looking cases displayed by my powder measure which to ponder for whatever reason.

In each of these three cases, the formed case came out longer than it was before going into the die. I personally witnessed the last two and only have second-hand anecdotal information on the first and that one was a long time ago, in another state and I have neither seen nor heard from those guys I barely knew since.
 

KeithB

Resident Half Fast Machinist
I would propose the following test. Take ten .223 cases, measure the OAL, Run five of them into a .222 die with and five without an expander ball. Remeasure the cases. Compare the results and publish it here. I would be very interested in seeing the data.
 

Spindrift

Well-Known Member
You could perhaps test the concept by grinding down a shell holder, instead of a die (much cheaper)
 

KeithB

Resident Half Fast Machinist
I used to make .222 cases from .223 brass. Always ended up trimming back the neck to standard .222 length cases and I don't recall measuring how long the cases were after forming but before trimming. If I still had a set of .222 dies I'd do the test I proposed as I have numerous once fired .223 cases on hand.
 

popper

Well-Known Member
grinding down a shell holder I've done both, die is much easier. Holder is really hard steel. I don't 'bottom/cam-over' the ram when sizing - that just wears the press.
 

Jeff H

NW Ohio
I used to make .222 cases from .223 brass. Always ended up trimming back the neck to standard .222 length cases and I don't recall measuring how long the cases were after forming but before trimming. If I still had a set of .222 dies I'd do the test I proposed as I have numerous once fired .223 cases on hand.

Give me a day or two and I'll see if I can find that many 223s and try it.

Have a really sick dog and it's the lady of the house's birthday today, so I'm sort of hanging around the house more than normal.
 

Jeff H

NW Ohio
Be glad to send you some empty .223 cases.

Let me check first. I have a small lot which I actually use, and believe there's still an ancient batch of LC-XX out there which has been loaded who knows how many times. This will be the first remotely "recreational" thing I've managed in quite some time, so I'm looking forward to it.

Thanks, Keith.