Dies for Bumping Shoulder

N

ninosdemente

New member
This is something I have not done when reloading and have been looking up mostly videos and minor reading regarding bumping shoulder. Has been mentioned a lot here in the forum and youtube videos/reading content. I use RCBS equipment and have FL dies for 6.5 Creedmoor/30-06/.223 Remington. With what I have, am I able to bump with getting additional bushings or would I need to get a separate die for this step? I have seen other dies and Forster/Redding has come up most often in the videos I have seen. Is it simply a sales video to get people to get "additional" reloading equipment when one can use what one already has? I have checked online but found no results for RCBS dies, unless not looking thoroughly. Thanks in advanced.

Up to this point I have been loading to book specs with FL sizing everytime.

Loading for:
Savage Model 111 30-06
Savage 12FV .223
Savage 12FV 6.5 creed
 
ninosdemente said:
This is something I have not done when reloading and have been looking up mostly videos and minor reading regarding bumping shoulder. Has been mentioned a lot here in the forum and youtube videos/reading content. I use RCBS equipment and have FL dies for 6.5 Creedmoor/30-06/.223 Remington. With what I have, am I able to bump with getting additional bushings or would I need to get a separate die for this step? I have seen other dies and Forster/Redding has come up most often in the videos I have seen. Is it simply a sales video to get people to get "additional" reloading equipment when one can use what one already has? I have checked online but found no results for RCBS dies, unless not looking thoroughly. Thanks in advanced.



Up to this point I have been loading to book specs with FL sizing everytime.



Loading for:

Savage Model 111 30-06

Savage 12FV .223

Savage 12FV 6.5 creed
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It sounds like you are already full length sizing, assuming you have your dies set properly. "Bumping the shoulder" is typically done when you are only partially sizing, or neck sizing only. It is referring to screwing in your die a bit farther until it contacts the case shoulder to ensure proper chambering.

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Are both of you very familiar with the term "headspace" as it applies to full length sizing dies, barrel chambers, rimless bottleneck cases and chamber headspace gauges? Same thing for "partial full length sizing?"

This can be very confusing unless we all use the same names, terms and conventions for each procedure, dimention element of the rifle barrel chamber, cartridge and reloading tools. That's not happening now.

Here's a good place to start:

https://saami.org/saami-glossary/
 
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Redding's definition of headspace is not the same as SAAMI's

Redding:

For bottlenecked cartridges, headspace is simply the distance between the head of the cartridge case (the end where the primer is inserted) and the front/face of the firearm's bolt when the case's shoulder is positioned against the front of the chamber.

SAAMI:

HEAD CLEARANCE
The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.

HEADSPACE
The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats. 1. BELT: A type of chamber design in which the cartridge seats in the chamber on an enlarged band ahead of the extractor groove of the cartridge body. 2. MOUTH: A type of chamber design in which the cartridge seats in the chamber on the mouth of the cartridge case. 3. RIMLESS: A type of chamber design in which the cartridge seats in the chamber on the shoulder of the cartridge case. 4. RIMMED: A type of chamber design in which the cartridge seats in the chamber on the rim or flange of the cartridge case.

It's also very common to define headspace on rimless bottleneck cases as the distance from the case head to the reference diameter on the shoulder. Example: 2.047" on a 30-06 case that has the same headspace as a 30-06 GO headspace gauge whose shoulder reference diameter is .375 inch.
 
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A simplified explaination would be something like...

Standard full length sizing dies are designed to resize the case enough for easy chambering in SAAMI spec chambers. If your resized/reloaded rounds chamber easily (bolt is easy to close on rounds) in your firearm, your dies are adequately sizing the brass case.

Setting the resizing die to resize the brass cartridge a minimum amount necessary to chamber easily is a matter of measurement of cases and adjustment of the sizing die. For some reloaders, minimal resizing is achieved by forming the brass so that the shoulder to case head dimension is a couple of thousands of an inch shorter than the shoulder to case head length of the firearm chamber (headspace dimension), IOW, achieve a couple thousandths of head clearance.
 
BBarn, good information in your post.

All the 30-06 full length sizing dies I've measured have headspace (distance from touching shellholder base to die chamber shoulder) about .005" less than a chamber GO headspace gauge: 2.042" so they'll end up making case headspace a few thousandths less than a minimum SAAMI spec chamber's 2.047" headspace.
 
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Am I confused? By using FL dies set as instructed I am "bumping" the shoulder back to make for an easy bolt closeing. I measure my fired cases with a comparator and set the dies to only "bump" my shoulder back .001" to .0015". By annealing, my cases are consistant in lenght. If I ever decided to neck size only, I would adjust my FL die to "bump" the shoulder back .000. I expand the neck with a separate mandrel.
 
If the fired case is full length resized without setting its shoulder back any amount, its body diameters will still be reduced or sized down a thousandth or more.
 
Thanks for the link and the explanation Bart. I have seen many videos where you mentioned headspace from your last sentence. To be honest, I have also thought that was headspace as well.

Bbarn, when I FL size, the brass does chamber easily as do check them when I size them.

Is bumping a requirement/needed then?

Reason why I started the thread is because I had previously made my own modified cases for 30-06 and .223 and was having difficult when getting measurements. Meaning, the projectile seem to far out and was really questioning my cases, my process. Not until recently this past week I got those same calibers from Hornady modified cases and found out my home made modifies cases were not right. They weren't fully inserting correctly. The Hornady ones fit way better than the ones I had made. I definitely did something wrong when I attempted to make them. Once I started to search this topic again, then bumping shoulder, .002" off the lance, headspace comparator kit, etc. were mentioned and was just trying to go step by step. As I fully don't have much understanding about this yet. Well do have an idea from what I read/seen online.
 
Bart B like Guffey gets all bent about head-space and all it does is cause more confusion (My opinion of course).

So, once you fire the round, you have conformed to your chamber (it shrinks just a bit so not exact but close)

Using an FL die, you reduce the case a bit until you get to the shoulder.

The goal of minimum bump back is to reduce or stop the stress on the area above the BASE that cracks by a FL and major shoulder move back.

A lot has to do with your chamber. If its a really long WWI 1917 and I go with the die mfgs (upwards of 1/4 turn) I take that formed to the chamber case and I really cram it back.

While not as bad, the target rifles are similar, its way too much push back if you go with die mfgs setup. The area above the thick part of the case at the base will see that stress and crack.

So, the idea is to bump the shoulder back enough its free bolt close ops and no bolt Resistance on closing but not so much as to crack the case at the base in 5-10 reloadings.

I got for a bit more than most do (.003) as my setup has some wander that if I don't I get the occasional tight bolt close.

So far I have yet to crack a base since I started doing so. Cracked cases are dangerous and more so in old rifles but having seen a modern file blown all to hell I think all are bad.

There is some discussion contention you have a better fitting round that is more accurate. No clue on that. I don't shoot good enough to tell.

Some contend you want a bit of bolt resistance ie. tight. No input on that either, I don't like it as its a wear aspect for the bolt lugs I don;t want to get into.

And personally, unless we are working on an engine and we are looking for really small tolerance of fit, being super technically accurate detracts from what the goal is of getting the ammo to a specificity condition.

I don't think it lends to the discussion and detracts from the method which is what we are after. If you can follow a recipe do you have to be a great cook?

Sure, American Test Kitchens explains whats going on and why it works, but if you follow what they tell you do do you get the same result without brain cells being hurt.

Maybe you go onto be a great Gun Chef and maybe not. I have worked into an understanding (my opinion again) without being bent about it all. I have the right mental picture of whats going on. If I don't, so what? I bump it back .003 or .002 or .001 and get the results I am after (bolt closes easily) then I am good arn't I?

Me, I get good re-loads (just ask me) and I am happy with the results (how well I shoot is a different story)

So yea, I get E=MC2, but I sure would not want to do the math (can't actually) - but yea, squash enough Uranium (etc) together fast enough and it gets a nasty mushroom cloud. I don't want that nor do I want to be around it, good enough. Fenyman I am not. But then I don't think he could target shoot as good as I can.
 
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RC20 said:
Bart B like Guffey gets all bent about head-space and all it does is cause more confusion (My opinion of course).

So, once you fire the round, you have conformed to your chamber (it shrinks just a bit so not exact but close)

Using an FL die, you reduce the case a bit until you get to the shoulder.

The goal of minimum bump back is to reduce or stop the stress on the area above the BASE that cracks by a FL and major shoulder move back.

A lot has to do with your chamber. If its a really long WWI 1917 and I go with the die mfgs (upwards of 1/4 turn) I take that formed to the chamber case and I really cram it back.

While not as bad, the target rifles are similar, its way too much push back if you go with die mfgs setup. The area above the thick part of the case at the base will see that stress and crack.

So, the idea is to bump the shoulder back enough its free bolt close ops and no bolt Resistance on closing but not so much as to crack the case at the base in 5-10 reloadings.

I got for a bit more than most do (.003) as my setup has some wander that if I don't I get the occasional tight bolt close.

So far I have yet to crack a base since I started doing so. Cracked cases are dangerous and more so in old rifles but having seen a modern file blown all to hell I think all are bad.

There is some discussion contention you have a better fitting round that is more accurate. No clue on that. I don't shoot good enough to tell.

Some contend you want a bit of bolt resistance ie. tight. No input on that either, I don't like it as its a wear aspect for the bolt lugs I don;t want to get into.

And personally, unless we are working on an engine and we are looking for really small tolerance of fit, being super technically accurate detracts from what the goal is of getting the ammo to a specificity condition.

I don't think it lends to the discussion and detracts from the method which is what we are after. If you can follow a recipe do you have to be a great cook?

Sure, American Test Kitchens explains whats going on and why it works, but if you follow what they tell you do do you get the same result without brain cells being hurt.

Maybe you go onto be a great Gun Chef and maybe not. I have worked into an understanding (my opinion again) without being bent about it all. I have the right mental picture of whats going on. If I don't, so what? I bump it back .003 or .002 or .001 and get the results I am after (bolt closes easily) then I am good arn't I?

Me, I get good re-loads (just ask me) and I am happy with the results (how well I shoot is a different story)

So yea, I get E=MC2, but I sure would not want to do the math (can't actually) - but yea, squash enough Uranium (etc) together fast enough and it gets a nasty mushroom cloud. I don't want that nor do I want to be around it, good enough. Fenyman I am not. But then I don't think he could target shoot as good as I can.
Click to expand...
And this post doesn't cause confusion saying the same as mine using different word sequences?
 
Bumping the shoulder huh? Don't suppose you can define just what bumping the shoulder means? You size the shoulder and you size the whole case equally! I like to use the term partial sizing but even that is wrong. You can't partially size a case with an FL dies unless you size only the neck! Once you have moved the shoulder at all you have actually full length sized the case. Bumping the shoulder or partial sizing it actually full length sizing to fit the chamber the case is fired in and maybe not any other. FL sizing dies come from the factory with instructions to set them up so that the ammo wll fit in any chamber. Then the OLL in the reloading manual is suggested so the loaded round will fit in any magazine for that cartridge. Depending on your rifle, you can adjust how much you full length the case in sizing, how much I don't know foe sure but any where from SAMMI min to SAMMI max! All instructions are for SAMMI min so they will fit every chamber without the case being overly worked on firing. OLL is set to match the length so that the round will fit in all magazine's and not touch the lands when laded that way. Full length sizing the best way, IMO, can make your case fit any chamber to one that is actually an over head space chamber. Take a case from a rifle with excessive headspace and neck size only till the action will no longer close on the case and then adjust the die to size the case till the bolt will close on it and you have FL size the case to that chamber. If you size a case for a chamber like that to min SAMMI spec's as they instruction's say to do, three or four shot's down the road you will likely separate the case at the head!

I think the term, bump the shoulder came about as a term for moving the shoulder just enough to allow the case to fit that certain chamber. I have two 243's, never had two of anything before. Each one has it's own set of dies set to FL size the case to that rifle. Ammo from one set of die's will fit in booth rifle's but from the other set, only one rifle, in the other the bolt won't close. In both case's the the case is full length sized for the particular rifle and I don't believe either is over SAMMI max spec.
 
Don,

"bump the shoulder" was first coined decades ago to mean setting the fired case shoulder back any amount. Sometimes the case neck will be sized down, too. There are dies that do both and don't size the case body down at all.

Fired cases typically easily fit the chamber after ejection without any resizing whatsoever. Except with most semiautomatic rifles.
 
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Bumping the shoulder means using a full-length sizing die. It is not a good phrase. It is as useful and specific as "tactitcal" and sounds equally "kewl" to "newbees".
Full-length sizing dies are usually set up (adjusted) to SAAMI specs by "reading the instructions". Rounds produced should fit every rifle chambered for the cartridge. The goal is tightest fit that will chamber (specific to ONE chamber/rifle). Variations exist in all chambers, so you may find better accuracy making minute adjustments of the sizing die upwards 1/16" at a time. This can tailor Your reloads to leave almost zero clearance at the shoulder in YOUR rifle's chamber. Note the "s" is singular and possessive. Not plural. Your gun may group better, but, the ammunition may not fit other guns. Same is also true with seating depth and COAL. By trial and error you can identify your chamber specifics (longest COAL and bolt to shoulder length that the bolt will close on.
Having ammo that will work in one gun but not the other can be a pain when you have 3 rifles in the same caliber.
If you are just starting reloading, it is OK to full-length size, using your dies instructions and speak specifically, so as not to BUMP your head-space on your boat when you need to use the toilet. Tinker with your die adjustments if you wish.
A better alternative is get and use a neck sizing die. The LEE Collet neck sizing dies work great. This leaves the shoulder as fire formed in your chamber. Better option than fiddling with your sizing die.
Avoiding overworking the brass by back and forth full sizing and fireforming when fired again.
 
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Full length resized brass meets my needs.I do fine tune setup for a desired head clearance.Mostly I try not to lose brass early to case stretch/stretch rings/head separations. Minimizing head clearance helps.Brass life is my motivation for controlling head clearance beyond whatever the dies deliver.
I'm not pursuing accuracy to the degree that I worry about .001 or .003 head clearance so far as any effect on accuracy. I'm just not in that world.

Some folks choose to pursue neck sizing. I'll respect they know what they are doing. I'm not interested in debating neck sizing.

But I believe you need the neck sizing die.

Some folks who reload believe there is benefit to just backing out a full length resize die. "Partial Sizing"

IMO,its a misguided process. If you use the case taper to calculate the diametrical change in sizing you get from backing up a full turn,depending on case taper,it will be less than .001 in.

It won't reduce the amount the brass is worked or retain "fireformed" fit to significant degree.

All it accomplishes is removing the shoulder area of the die from the sizing operation.

Whether you consider the shoulder inside the sizing die a "bump"or simply a boundary to control the case shoulder during sizing,

Imagine putting a half bananna in your hand and "sizing it down" . The ends will extrude in an uncontrolled fashion.

By backing the shoulder of the die out of the operation,the shoulder geometry and dimensions are uncontrolled during partial sizing.

Variation is inevitable.

If you choose to neck size,get the die and do it right.

I can see no reason to partial size. Now,if you use a .003 (or whatever) feeler gauge between the shellholder and die body in setup to control head clearance,thats ,IMO,still full length sizing and the die still provides a boundary for the shoulder.
 
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"Partial sizing" with the FL die 5 to 100 thousandths above the shell holder and the press ram topped out has always moved the case shoulder forward. Resizing the body down pushed the case shoulder forward.

One can use Redding competition shellholders to better control resized case headspace and shoulder bump. A set of 5 with .002" incremental deck heights makes shoulder bumping easy and precise when the shellholder stops against the die.
 
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Agreed,Bart. I see nothing to be gained by removing the shoulder portion of the FL resizing die from the sizing operation. That's what "partial sizing" does.

The shoulder is uncontrolled as the case body is sized down.
 
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