How to bump back the shoulder

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RedSkyFarm

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Question for you all. I’ve read from time to time about the need to bump the shoulder back on a case. I normally neck size my cases knowing that eventually the shoulder will need to be bumped back in order to smoothly close the bolt and chamber the round. The time has come that my cases are too long between the head and the shoulder. Brass is still in good shape. I have RCBS “standard” dies. When I run a case up in the FLS die, the shoulder is not even touched. Actually, it grows .001-.0015”. The shell holder is bottoming out on the bottom of the die. Other than grinding the bottom of the die (or the top of the shell holder), how do I use the shoulder portion of the die?? Is there a better die made to contact the shoulder before it bottoms out? Or am I missing something? I am measuring from the case head to the datum using a comparator. I took baseline measurements when the cases were new and recorded them. At this point, my cases are .006-.008 longer than when they were new. This is an Interarms 25-06 bolt action. Any input will be appreciated. Thanks.
 
Is there a better die made to contact the shoulder before it bottoms out? Or am I missing something?
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Since you neck size, the additional die you want to bump back the shoulder is the Redding Body Die. It resizes the body and bumps the shoulder back without touching the neck. Myself and most everybody on the line used it in 1,000 yard F Class Competition in past years. Hope that helps.

Don
 
Just grind a bit off the shellholder. I’ve had to do that for one caliber/rifle. Fast and easy solution. And since it’s the cheapest component, I didn’t mind trying that approach.
 
Do the sized cases chamber in you rifle even though there .001-.0015 longer ? I'm thinking your cases are expanding causing hard chambering and bolt lift . I'm using the same die as you only with the Redding Competition Shellholder set of 5 to adjust case headspace to .001-.002 no more or less , also I am using the expander ball , are you checking your trim lengths . I wouldn't shave down anything until you know for sure what's going on , this is the first time your full sizing your neck sized cases ?
 
scatter
That will help to give you a few thousands , I'm not sure his problem is headspace . He has been neck sizing only , how hot is he loading or how many reloads on the cases . He sized the cases and they grew .0015 from base to datum but did they chamber , he hasn't responded yet. I'll bet they do .
 
CW308, as I understand it, when he fully resized the case it grew in length by .0015. When he squeezes the case up the die the length will grow as the decreased dia. must go somewhere. If he needs to go futher up the die would a shim not do it? I keep shims on the press base ( I check the lenght of every case before sizing and after) if I need an additional push. Regardless of how hot he is loading, the case will only expand to fit the chamber, if he's not blowing something up.
 
OK, guys (you know who you are). Cut the snark attacks and personal attacks veiled as humor. They violate board rule 3., which expressly forbids them and will garner you infraction points. In this instance, I have removed or edited the posts involved.


RedSkyFarm said:
…When I run a case up in the FLS die, the shoulder is not even touched. Actually, it grows .001-.0015”. The shell holder is bottoming out on the bottom of the die. Other than grinding the bottom of the die (or the top of the shell holder), how do I use the shoulder portion of the die??…
Click to expand...

The case grows because the sides of the FL die squeeze it narrower and the extra brass then has to go somewhere, so the shoulder is moved forward. When you get to the die making contact with the shell holder, the brass in the shoulder is then funneled inward, extruding it out into the neck, which is how case growth and the need to trim necks comes about.

In this instance, unless your chamber is unusually tight, I think you will find your die mouth is not actually making contact with the shell holder when a case is inside it. Instead, the force of the case shoulder on the die is stretching the press slightly, causing a gap to form between the shell holder and the case mouth. You can test this by running a lubricated case up into the die and then either turning on a flashlight behind the die mouth and looking for a crack of light between the two "mating" parts, or else take a set of feeler gauges and see if you can slide the finer ones between the case mouth and shell holder. Bear in mind this happens during resizing effor and not when you are setting up the die. Most folks just turn the die into contact with the shell holder, back the press ram down and then turn the die another 1/8 to 1/4 turn (3.8 to 3/4 turn for an aluminum frame press) so the press ram actually applies some stretch to the press, too. As long as this is more stretch than the brass applies to it, contact will be made during resizing that was not made before.

Now, is this going to be too much length resizing? If so, slowly back the resizing die threads out until you get what you want. Each turn of the die is slightly over 70 thousandths, so once you reach the point that the cases are getting longer again, you only need about a 70th of a turn for each thousandth of change you want to make.

Are you still going to get too little resizing? I doubt it, but if you did, remove the decapper from the die and slip a 0.002" or 0.003" feeler gauge between the head and bottom channel of the shell holder with the case in place, and then resize it. You would then get the case that much shorter than you are getting it now.

Here's an exaggerated drawing of what goes on in normal resizing.

attachment.php
 
scatter
Yes , what I'm saying I don't think his cases are too long , I would like to know if his sized cases chamber fine in his rifle . Never liked the idea of neck sizing , I like all my sized cases to be as close to exact as possible , neck sizing fire formed cases , are they all exact , I don't think so . Some may form differently , they all don't chamber hard at the same time . Using the shims to take up the wiggle in the shellholder will help in bumping the shoulder , better to try that first then to make any changes in the shellholder or die .
Hard enough squaring a piece of wood , can't imagine a shellholder or die . Better know what your doing and the right tools to do it with . I try to do things simple first . May take awhile to dope it out what's really going on , it will finally work out with help from my forum friends . Be Well .

Chris
 
Back in the old days we used our neck sizing dies until the cases started getting hard bolt closure . A trip through a full length sizing die got you back to square one .
Trim the cases and you were ready to start back neck sizing in the quest for accuracy .
Some would anneal neck / shoulder prior to the full length resizing hoping to extend case life.
Case life was good and cases were plentiful with the 30-06 I was shooting so I never bothered much with annealing .
Gary
 
Sorry for taking awhile to get back. Thanks to all who replied. I was “experimenting”. Cw308, the cases were already .006-.008” longer before I initially resized them. Then another .001-.0015 after. I could chamber the round at that point, but was hard. I’m preparing for a hunt and didn’t want that to be a problem. Uncle Nick hit the nail on the head (again). At full stroke I had a .004” gap between the shell holder and the ram. With some Prussian blue, I was able to adjust until I had contact, then adjusted from there. Again, thanks for all the input. USSR, what is the difference between a body die and a small base die. Does the small base size the body even smaller?
 
gw
Never got into using heat , I just pick 90 cases per season , shooting 30 cases each range trip and rotating the 3 groups of 30 , works for me and they all last the whole season. All full length every firing , for me it's more accurate in every way . Be Well .

Chris
 
Unclenick
Do I detect the expander ball in your diagrams ? Just busting them . As always great diagrams .
 
USSR, what is the difference between a body die and a small base die. Does the small base size the body even smaller?
Click to expand...

As previously stated, a body die resizes only the body and bumps back the shoulder without resizing the neck. A small base die resizes the body further down than a regular die does. In most cases it is not necessary. The only time I've used it was when I bought some once-fired USGI 7.62x51 brass that had been fired in a M60 machine gun with an enormous chamber that expanded the web area so much that resized brass from a standard die would not chamber. What a nightmare!

Don
 
Once again, love the illustration Unclenick!

Granted it is an exageration, but almost looks like your taking a SAAMI case, fire forming to Ackley Improved, then trying to make it back to SAAMI.

Myself, i've not yet run into an issue with neck sizing only.
My method for "bumping back a shoulder" would involve a Lee wack-a-mole reloader and a 3lb hammer.
 
I thought all along your die was set up with the die bottoming on the shellholder , Sorry . How is your accuracy with neck sizing and after full sizing .
 
The drawing is greatly exaggerated to show what each part of the sizing operation does. Yes, that's an expander working at the end. Theoretically, if you have dead minimum wall thickness the ideal die neck will just get it back to bullet grip and the expander will barely touch it.

The original drawing just had the first three elements (from left to right) in order to show how the relationships between the neck and shoulder changes at each step. I added the fourth to avoid confusion by having the operations incomplete.


RedSkyFarm,

Just to rephrase the descriptions, a small base die is like a normal full-length sizing die, but slightly smaller on the inside. There are some kinds of chambers so wide that it takes more resizing squeeze to get their brass back in line than it does for normal brass. Once-fired brass from full-auto weapons is sometimes like that. Also, you occasionally run into a gun that won't feed reliably without the case being on the small side of SAAMI standard, and a small base die will get you there. We've had a couple of AR owners state their guns are like that. Mine does care, and it's got a tight match chamber, so I am not clear what causes this and don't have a gun with the problem to be able to look at it up close.

The body die, if you can imagine it, is like a regular size full-length sizing die that has had its neck sizing portion honed to the width of the largest chamber diameter, so it never touches the expanded neck of a fired case. It also has no decapper or expander. It is just the sizing part of the die body. I use one in conjunction with the Lee Collet Neck Sizing dies to get maximally straight, concentric cases. It works well.
 
After all these years? I have said it is impossible to move the shoulder back with a die that has case body support. I do not care what thinking process reloaders use; but, it would seem if a couple would use deductive reasoning they would say it is also impossible to bump the shoulder back for the same reason. For years and years I have said there are cam over presses and there are non cam over presses; I have described the cam over press as a bump press. The bump has to do with cam over; the case on top of the ram bumps the die twice, once on the way up and once on the way down; and yes, the bump press when adjusted for sizing is adjusted differently than the non bump press.

And then there is search and there are archives; in the beginning bump had nothing to do with moving the shoulder back; when sizing and case forming I am the only reloader that finishes with a different shoulder than he started with. It is mind boggling, it has to be; if not mind boggling why do reloaders insist the case had head space when SAAMI does not list head space for the case because they do not use the head space symbol with their case drawings.
I understand you all have friends that insist you agree with them;

F. Guffey
 
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