Dies for Bumping Shoulder

ninosdemente · October 26, 2019, 03:31 AM

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

Old_School · October 26, 2019, 06:50 AM

Quote:

Originally Posted by ninosdemente

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

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.

Sent from my moto z4 using Tapatalk

Bart B. · October 26, 2019, 08:20 AM

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/

ninosdemente · October 26, 2019, 09:18 AM

I came across these two sites among others regarding headspace when looking online:

https://www.redding-reloading.com/te...with-headspace
https://www.sinclairintl.com/guntech....htm?lid=17125

Bart B. · October 26, 2019, 09:33 AM

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.

BBarn · October 26, 2019, 09:41 AM

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.

Bart B. · October 26, 2019, 09:51 AM

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.

scatterbrain · October 26, 2019, 10:58 AM

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.

Bart B. · October 26, 2019, 11:03 AM

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.

ninosdemente · October 26, 2019, 11:04 AM

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.

RC20 · October 26, 2019, 11:23 AM

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.

Ernie Bishop · October 26, 2019, 11:25 AM

Sent you a PM ninosdemente

Bart B. · October 26, 2019, 11:48 AM

Quote:

Originally Posted by RC20

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.

And this post doesn't cause confusion saying the same as mine using different word sequences?

Don Fischer · October 26, 2019, 12:17 PM

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.

Bart B. · October 26, 2019, 01:57 PM

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.

Ernie Bishop · October 26, 2019, 03:37 PM

nino,
Consider this vid to be #2 from what I sent from Jeff.
https://www.youtube.com/watch?v=anhesQg4uZg

Marco Califo · October 26, 2019, 03:45 PM

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.

HiBC · October 26, 2019, 03:45 PM

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.

Bart B. · October 26, 2019, 03:57 PM

"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.

HiBC · October 26, 2019, 04:14 PM

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.

Don Fischer · October 26, 2019, 05:23 PM

My introduction to partial sizing came many years ago with a 7mm mag. Found out it had what they called a sloppy chamber And by 5 shot's was getting case head separations. To fix the problem I partial sized sized the case's and when done the case fit the chamber much better. I understand a lot of belted magnums are that way. They headspace on a belt rather than the shoulder. If the chamber is sloppy your gonna get head separations. Moved to cartridge headspacing on the shoulder and the problem goes away.

RC20 · October 26, 2019, 06:30 PM

Quote:

And this post doesn't cause confusion saying the same as mine using different word sequences?

It takes head space out of the discussion (which we are not really talking about anyway_) and tell you what you want to do, simply move the should back .003 or .004.

Each to his or their own, its an alternative approach and I think simpler.

More accurate as head space is actually the distance from the face of the bolt to the datum point on the shoulder (and the relaxed case is not that let alone one with a bumped shoulder)

Head space is for setting a barrel on a gun. The case aspect revolves around tthat planet quite loosely in technical terms .

Bart B. · October 26, 2019, 07:53 PM

What's headspace on a rimless bottleneck chamber gauge?

What's wrong with measuring the case the same way for a comparison?

Especially when there's a few to several thousandths spread in tolerances for cases and chanbers.

603Country · October 26, 2019, 08:03 PM

Some of ya’ll can make a simple thing difficult. Over the decades, I’ve full length sized, neck sized, partial resized, and used FL Bushing dies. These days I do a Partial FL Resize, which varies with rifles I load for. My 220 requires me to FL size as much as the die allows, due to a snug chamber. But if you have what we can call a “loose chamber”, a max FL resize might overdo it and eventually lead to case head separations. You size the brass too much (too small, for lack of a better term) and overwork the brass. My 223 is like that. The answer is to simply resize the case ‘enough’ and not overmuch. That’s what I now do. It gives consistent case sizes and no head separations. You can determine how much sizing is just right by trial and error, or Unclenick can tell you how to do it more scientifically.

Note that I didn’t describe it a bumping the shoulder. All you are doing is resetting the shoulder very slightly.

ninosdemente · October 26, 2019, 08:36 PM

Thanks guys for everyone's input... has been helpful. I can't add any type of response as mentioned have no idea on this matter. Don't want to make myself look dumb with a comment, lol. Do have questions, but many have responded without me asking so far.

Ernie, thanks for both videos.

Bart, another member also mentioned about the Redding competition shellholders.

October 26, 2019, 03:31 AM	#1
ninosdemente Senior Member Join Date: March 23, 2017 Location: Northwest Indiana Posts: 831	Dies for Bumping Shoulder 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

October 26, 2019, 08:20 AM	#3
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	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/ Last edited by Bart B.; October 26, 2019 at 09:23 AM.

October 26, 2019, 09:33 AM	#5
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	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. Last edited by Bart B.; October 26, 2019 at 09:42 AM.

October 26, 2019, 09:51 AM	#7
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	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. Last edited by Bart B.; October 26, 2019 at 10:50 AM.

October 26, 2019, 11:23 AM	#11
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	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. __________________ Science and Facts are True whether you believe it or not Last edited by RC20; October 26, 2019 at 11:31 AM.

October 26, 2019, 09:18 AM	#4
ninosdemente Senior Member Join Date: March 23, 2017 Location: Northwest Indiana Posts: 831	I came across these two sites among others regarding headspace when looking online: https://www.redding-reloading.com/te...with-headspace https://www.sinclairintl.com/guntech....htm?lid=17125

October 26, 2019, 09:41 AM	#6
BBarn Senior Member Join Date: December 22, 2015 Posts: 887	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.

October 26, 2019, 10:58 AM	#8
scatterbrain Senior Member Join Date: February 7, 2015 Posts: 160	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.

October 26, 2019, 11:03 AM	#9
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	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.

October 26, 2019, 11:04 AM	#10
ninosdemente Senior Member Join Date: March 23, 2017 Location: Northwest Indiana Posts: 831	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.

October 26, 2019, 11:25 AM	#12
Ernie Bishop Senior Member Join Date: October 21, 2019 Posts: 122	Sent you a PM ninosdemente

October 26, 2019, 12:17 PM	#14
Don Fischer Senior Member Join Date: March 2, 2017 Posts: 1,868	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.

October 26, 2019, 01:57 PM	#15
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	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. Last edited by Bart B.; October 26, 2019 at 03:46 PM.

October 26, 2019, 03:37 PM	#16
Ernie Bishop Senior Member Join Date: October 21, 2019 Posts: 122	nino, Consider this vid to be #2 from what I sent from Jeff. https://www.youtube.com/watch?v=anhesQg4uZg

October 26, 2019, 03:45 PM	#17
Marco Califo Senior Member Join Date: April 4, 2011 Location: LA (Greater Los Angeles Area) Posts: 2,598	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. __________________ ............ Last edited by Marco Califo; October 26, 2019 at 05:04 PM.

October 26, 2019, 03:45 PM	#18
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	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. Last edited by HiBC; October 26, 2019 at 04:09 PM.

October 26, 2019, 03:57 PM	#19
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	"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. Last edited by Bart B.; October 26, 2019 at 04:18 PM.

October 26, 2019, 04:14 PM	#20
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	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.

October 26, 2019, 05:23 PM	#21
Don Fischer Senior Member Join Date: March 2, 2017 Posts: 1,868	My introduction to partial sizing came many years ago with a 7mm mag. Found out it had what they called a sloppy chamber And by 5 shot's was getting case head separations. To fix the problem I partial sized sized the case's and when done the case fit the chamber much better. I understand a lot of belted magnums are that way. They headspace on a belt rather than the shoulder. If the chamber is sloppy your gonna get head separations. Moved to cartridge headspacing on the shoulder and the problem goes away.

October 26, 2019, 07:53 PM	#23
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	What's headspace on a rimless bottleneck chamber gauge? What's wrong with measuring the case the same way for a comparison? Especially when there's a few to several thousandths spread in tolerances for cases and chanbers. Last edited by Bart B.; October 26, 2019 at 08:14 PM.

October 26, 2019, 08:03 PM	#24
603Country Senior Member Join Date: January 6, 2011 Location: Thornton, Texas Posts: 3,998	Some of ya’ll can make a simple thing difficult. Over the decades, I’ve full length sized, neck sized, partial resized, and used FL Bushing dies. These days I do a Partial FL Resize, which varies with rifles I load for. My 220 requires me to FL size as much as the die allows, due to a snug chamber. But if you have what we can call a “loose chamber”, a max FL resize might overdo it and eventually lead to case head separations. You size the brass too much (too small, for lack of a better term) and overwork the brass. My 223 is like that. The answer is to simply resize the case ‘enough’ and not overmuch. That’s what I now do. It gives consistent case sizes and no head separations. You can determine how much sizing is just right by trial and error, or Unclenick can tell you how to do it more scientifically. Note that I didn’t describe it a bumping the shoulder. All you are doing is resetting the shoulder very slightly.

October 26, 2019, 08:36 PM	#25
ninosdemente Senior Member Join Date: March 23, 2017 Location: Northwest Indiana Posts: 831	Thanks guys for everyone's input... has been helpful. I can't add any type of response as mentioned have no idea on this matter. Don't want to make myself look dumb with a comment, lol. Do have questions, but many have responded without me asking so far. Ernie, thanks for both videos. Bart, another member also mentioned about the Redding competition shellholders.