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Old December 1, 2018, 08:25 AM   #1
RedSkyFarm
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How to bump back the shoulder

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.
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Old December 1, 2018, 08:45 AM   #2
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Is there a better die made to contact the shoulder before it bottoms out? Or am I missing something?
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
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Old December 1, 2018, 12:36 PM   #3
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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.
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Old December 1, 2018, 01:04 PM   #4
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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 ?
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Old December 1, 2018, 01:15 PM   #5
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Mr. Guffy may suggest you place a shim between the case and shell holder, works very well for me.
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Old December 1, 2018, 02:32 PM   #6
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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 .
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Old December 1, 2018, 03:17 PM   #7
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as Erik Cortina says - http://bulletin.accurateshooter.com/...ing-is-better/

Only time i use a Lee collet is if I have ran it through a Redding body die first
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Old December 1, 2018, 03:17 PM   #8
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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.
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Old December 1, 2018, 03:32 PM   #9
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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.


Quote:
Originally Posted by RedSkyFarm
…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??…
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.

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Old December 1, 2018, 06:07 PM   #10
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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
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Old December 1, 2018, 06:23 PM   #11
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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
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Old December 1, 2018, 06:51 PM   #12
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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?
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Old December 1, 2018, 06:51 PM   #13
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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
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Old December 1, 2018, 06:53 PM   #14
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Forgot to mention, feeds and extracts smooth now.
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Old December 1, 2018, 06:58 PM   #15
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Do I detect the expander ball in your diagrams ? Just busting them . As always great diagrams .
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Old December 1, 2018, 07:02 PM   #16
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Quote:
USSR, what is the difference between a body die and a small base die. Does the small base size the body even smaller?
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!

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Old December 1, 2018, 07:17 PM   #17
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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.
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Old December 1, 2018, 07:30 PM   #18
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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 .
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Old December 1, 2018, 07:56 PM   #19
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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.
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Old December 2, 2018, 11:14 AM   #20
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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;

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Old December 2, 2018, 11:24 AM   #21
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Quote:
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 .
Not me, not my dies: I have no problem using a full length sizing die for neck sizing. I use very simple rules when using the full length sizing die for neck sizing. I adjust the de off the shell holder; is have used a feeler gage to adjust the die off the shell holder to prevent the body of the case from being sized. A reloader with a little shop skill should not have trouble determining how far the die is adjusted down to start the die from sizing the case body. And then there is the advantage of partially sizing the neck as in leaving part of the neck upsized' they say the unisized portion of the neck that is not sized helps center the case.

And then there is that 'saying', after neck sizing 4 times the reloader must start over by full length sizing and I ask how is it possible to start over if the case had been fired 5 times?

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Old December 2, 2018, 12:26 PM   #22
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How to bump back the shoulder
It is not possible to bump the shoulder back; I am the only reloader that can reduce the length of the case from the datum to the case head without bumping the shoulder back because I am the only reloader that understands the shoulder I finish with is not the same shoulder I started with.

It believe it is easier for me because my cases do not have head space; my cases do not have head space because SAAMI does not use the head space symbol in their case drawings. I off set the length of the chamber from the shoulder of the chamber to the bolt face with the length of the case from the shoulder to the case head.

Years ago I suggested reloader scribe the case at the case body/shoulder juncture when trying to determine what happens to the case when sized. I even suggested that is what Hatcher should have done when he was trying to work out problems with case head separation. He was convinced a chamber that was .060"+ was to long for a short case that was .060" shorter from the case shoulder to the case head than the chamber from the shoulder of the bolt face. Had he scrivewd the case body/shoulder juncture he would have know what happen the shoulder of the case when fired and when sized. AND! then there was the length of the neck.

And there were other factors, he could have eliminated a few, not all 03s were alike.

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Old December 2, 2018, 12:50 PM   #23
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Cw308. I thought I was bottomed out. I was not. The ram was at the top of the stroke and I ASSUMED (we all know what that gets us!) that I was bottomed out. After getting the feeler gauges out, I discovered I wasn’t. Then made adjustments from there. As far as neck sizing, I initially with new brass would run all through the FLS die before loading. Then neck size the fired brass from that point. Neck sizing was more accurate in my case. I have a chamber that is .003-.004” longer than an unfired case. So now that I know how to properly full length size a piece of brass, I will see what the difference between the two are. That has yet to be determined. I’ll give an update as soon as I fire some and find out.
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Old December 2, 2018, 01:24 PM   #24
F. Guffey
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Quote:
I have a chamber that is .003-.004” longer than an unfired case.
If I had one of those I would have a short chamber because we all know the chamber is reamed to go-gage length and the case is sized to minimum length/full length sized.

What does that mean? If you placed a .003" feeler gage between the deck of the shell holder and case head you would eliminate the clearance between the shoulder of the case and shoulder of the chamber.

And then there is that part about determining the winner; if the die makes it down to the top of the shell holder with zero clearance the press wins. If there is clearance between the bottom of the die and top of the shell holder the case wins; MEANING! the case has more resistance to sizing than the press can overcome.

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Old December 2, 2018, 01:52 PM   #25
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A case being sized down in diameter by a FL sizing die is supported,at least on the outside.

Aside from some silly word puzzle argument,if a case is checked in an RCBS Precission Mic or a bushing type "Cartridge headspace gauge" .(As the manufacturer calls them)

And if I run it through the FL sizer die and it comes into spec,the case head to shoulder datum length has been reduced.

That's the desired result,Mr Guffey.All the rest of the reloaders(except you) call that bumping or setting the shoulder back.

Apparently you are the "Only Reloader" who cannot perform the shoulder adjustment that the rest of the reloaders have been doing since FL sizing dies have been produced.

One more thing: I agree with using technically correct language. What brief,technically correct ,reasonably universally understood terminology do you have to offer to describe the measurement of the cartridge brass from the case head to the datum feature that contacts the firearm chamber headspacing feature? In other words,what do YOU have to offer instead of the often used (FOR LACK OF A BETTER TERM) "Cartridge Headspace"

If you do not have such a term to offer,why don't you stop obstructing and confusing and making it harder to answer questions?

Last edited by HiBC; December 2, 2018 at 02:33 PM.
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