Shoulder bump question

[BoydAllen]

For my tight necked 6PPC I do not want the barrels chambered to absolute minimum headspace. Let me explain why. Typically, I make my cases for this caliber from .220 Russian brass that has had its necks expanded, and then turned. When they are expanded, the thicker brass at the top of the shoulder becomes the base of the neck. In order to get the feel that I want when chambering rounds for their fire forming shot, with chamber headspace set at .0035 over minimum, I have to turn the necks so that the chamfer at the leading edge of my turner's cutter makes a track on the shoulder of the case that forms a minuscule step. If my chambers were at minimum, the step would have to be deeper, and to what purpose? Additionally, I have found that as brass is reused and it work hardens, even with this additional headspace, I have to use a shell holder that has had material turned off if its top surface so that I can bump back the shoulders of work hardened cases. I have barrels that were intentionally chambered over minimum, to a matching and specific headspace, and I have a barrel that I friend did for me who gets some comfort from setting them up at absolute minimum, and yes he has the proper gauge. My experience for this caliber is that I prefer not having to turn quite so far into shoulders as the minumum headspace barrel requires. I admit that this is a somewhat unique situation, but it is real world, and there are quite a few 6PPCs out there. Of course if you are using Norma brass that does not need to be necked up from .22 to 6mm, it would not apply, but no one that I know has taken up that option for their competition applications.

 

[mike06]

I do not have any custom barrels on my rifles. I do use the redding competition shell holders with my body die and I also use a Forster bushing bump die along with Micrometer seating dies.

 

[dedogs]

For my tight necked 6PPC I do not want the barrels chambered to absolute minimum headspace. Let me explain why. Typically, I make my cases for this caliber from .220 Russian brass that has had its necks expanded, and then turned. When they are expanded, the thicker brass at the top of the shoulder becomes the base of the neck. In order to get the feel that I want when chambering rounds for their fire forming shot, with chamber headspace set at .0035 over minimum, I have to turn the necks so that the chamfer at the leading edge of my turner's cutter makes a track on the shoulder of the case that forms a minuscule step. If my chambers were at minimum, the step would have to be deeper, and to what purpose? Additionally, I have found that as brass is reused and it work hardens, even with this additional headspace, I have to use a shell holder that has had material turned off if its top surface so that I can bump back the shoulders of work hardened cases. I have barrels that were intentionally chambered over minimum, to a matching and specific headspace, and I have a barrel that I friend did for me who gets some comfort from setting them up at absolute minimum, and yes he has the proper gauge. My experience for this caliber is that I prefer not having to turn quite so far into shoulders as the minumum headspace barrel requires. I admit that this is a somewhat unique situation, but it is real world, and there are quite a few 6PPCs out there. Of course if you are using Norma brass that does not need to be necked up from .22 to 6mm, it would not apply, but no one that I know has taken up that option for their competition applications.

I find this to be very good information that explains and solves a couple of problems I have seen in the past. Thanks Boyd. dedogs

 

[dkhunt14]

I have read this entire string and there are some intelligent and lucid comments....but, if I set up a dial caliper with a comparator to check headspace and zero it it with a headspace gauge and my fired brass is .007" longer {over zero} the absolute first thing I am going to do is check headspace on the rifle!!!!!!!!!!!!!!!The second thing I am going to do is fix the GD thing, because unless it's an M-1 Garand that typically stretches brass .008"....there is a problem. Once I have a rifle that gauges with dead on zero headspace then I will start worrying about reloading for it. And don't even try to tell anyone that .004" headspace is "okay", because we all want zero. If I barrel a rifle for you and tell you, "yeah, missed the headspace a little...so I just left it at .004".....yeah okay right, and you are not going to have me set back, rechamber and do it right????

This is typical for a factory case verses fired. I have seen then even more. The factory makes then to fit every chamber out there. Typically they are really plenty small. Measure factory ammo headspace and fire it and measure again. You will see most grow alot. Matt

 

[ranger3]

This is interesting, twould of my rifles, a 243 and a 6.5 Creedmoor show very little growth, in fact my 243 often gets 2 or more firings with no more than neck sizing, then maybe a bump back with my Forster shoulder bump die and it is good to go. I set the headspace on both of these, the Creedmoor being a factory Savage barrel shooting factory ammo in the .3 ''s .

 

[msinc]

This is typical for a factory case verses fired. I have seen then even more. The factory makes then to fit every chamber out there. Typically they are really plenty small. Measure factory ammo headspace and fire it and measure again. You will see most grow alot. Matt

I don't shoot factory ammo, ever. I have never measured any. As I understand it, there is a .004" range for headspace with most cartridges...says SAAMI. That is, measured from case head to datum line {in the case of a rimless rifle cartridge} so, a go gauge is zero dead on plus zero. A no-go gauge is zero minus .004". We all know a rifle is not considered safe if it will close and go to battery on a no-go gauge. Go back and read my post...I said if a caliper is zeroed on a go gauge and the fired ammo is .007" longer than zero there is something wrong that needs to be fixed. This is especially true if the rifle is a bolt gun. So, zeroing the headspace gauge on an unfired case and then checking it after you fire it in a given rifle tells us something, but not much. If ammo is fired in a bolt action rifle with a zero headspace chamber it cannot "grow" but a couple thousandths over zero headspace. How short the case is when it goes into the chamber does not dictate how long it will get over headspace zero...only the chamber can allow it to do that and if so then the chamber is out of spec and needs to be fixed to be safe, period, end of story.
Maybe another way to say it is that I chamber all my rifles to minimum headspace so I can feel the bolt cam over on the go gauge. I size my brass to either exactly that length or .001", sometimes .002" under. Once fired they stretch typically .002". no more. If I had sized them to less than headspace they will not stretch to more than .002" over the size of the chamber. If they do then I didn't chamber the rifle correctly.
You can measure an under headspace case, fire it and call that stretch or any thing else you want to, but the factis that excess headspace, what ever the cause is dangerous and needs to be corrected, whether it is a bad chamber or bad ammo. .007" excess headspace is too much and something needs attention. Bottomline, if .007" is "typical" then somebody somewhere is messing up severely.

 

[dkhunt14]

I don't shoot factory ammo, ever. I have never measured any. As I understand it, there is a .004" range for headspace with most cartridges...says SAAMI. That is, measured from case head to datum line {in the case of a rimless rifle cartridge} so, a go gauge is zero dead on plus zero. A no-go gauge is zero minus .004". We all know a rifle is not considered safe if it will close and go to battery on a no-go gauge. Go back and read my post...I said if a caliper is zeroed on a go gauge and the fired ammo is .007" longer than zero there is something wrong that needs to be fixed. This is especially true if the rifle is a bolt gun. So, zeroing the headspace gauge on an unfired case and then checking it after you fire it in a given rifle tells us something, but not much. If ammo is fired in a bolt action rifle with a zero headspace chamber it cannot "grow" but a couple thousandths over zero headspace. How short the case is when it goes into the chamber does not dictate how long it will get over headspace zero...only the chamber can allow it to do that and if so then the chamber is out of spec and needs to be fixed to be safe, period, end of story.
Maybe another way to say it is that I chamber all my rifles to minimum headspace so I can feel the bolt cam over on the go gauge. I size my brass to either exactly that length or .001", sometimes .002" under. Once fired they stretch typically .002". no more. If I had sized them to less than headspace they will not stretch to more than .002" over the size of the chamber. If they do then I didn't chamber the rifle correctly.
You can measure an under headspace case, fire it and call that stretch or any thing else you want to, but the factis that excess headspace, what ever the cause is dangerous and needs to be corrected, whether it is a bad chamber or bad ammo. .007" excess headspace is too much and something needs attention. Bottomline, if .007" is "typical" then somebody somewhere is messing up severely.

Like I said if it's factory ammo or new cases they can easily be .007 under. I have seen factory ammo .010 under. This is common. Maybe you need to measure new cases. It will just blow out to chamber length like an Ackley. One firing and the stretching that goes with it will not hurt the case. I have blown them .100 forward. Matt

 

[msinc]

Like I said if it's factory ammo or new cases they can easily be .007 under. I have seen factory ammo .010 under. This is common. Maybe you need to measure new cases. It will just blow out to chamber length like an Ackley. One firing and the stretching that goes with it will not hurt the case. I have blown them .100 forward. Matt

I get what you are saying, but factory cases that are under do not equal or are not the same as a chamber that is over sized. The one is only dangerous by and of itself, you identify and don't use until corrected...the other is a danger, no matter what ammo is used and must be corrected or someone is going to get hurt. And no, it doesn't just "blow out to chamber length like an Ackley", sometimes it separates and sometimes it wrecks the gun and or the shooter. Excess headspace DOES NOT CORRECT ITSELF and it is ALWAYS DANGEROUS, no matter what the cause.
There is a big, galactic difference between blowing a shoulder forward .100" with zero headspace {such as fire forming an Ackley} and having excess headspace in a chamber.
To begin with, there is zero chance you can have .100" headspace and still have the striker hit hard enough to set off the case....firing pin protrusion is typically .060". If you were to seat the bullet out far enough to hit the lands and hold the case head against the bolt now you can do it, but then you have corrected for the excess headspace...so it's not the same. That is not stretching, that is fire forming.
The idea that you can take a rimless case, "bump the shoulder back .100" so it flops around in the chamber by almost 1/8" and fire it???? Come on dude, even you know better than that.
Bottom line, if you believe you can dismiss excessive headspace this way, well...you can be the next Darwin Award recipient. Let me ask you another way...just how much headspace do you believe is safe and at what point do you believe it might start to get a little dicey????? If .100" is Okay then where do you draw the line and not shoot the gun??? Why would SAAMI bother to make the no-go gauge only .004" longer than the go gauge ????? Especially if .100" is not going to be a problem????? Isn't the word "NO-GO" your first clue?????

 

[dkhunt14]

I get what you are saying, but factory cases that are under do not equal or are not the same as a chamber that is over sized. The one is only dangerous by and of itself, you identify and don't use until corrected...the other is a danger, no matter what ammo is used and must be corrected or someone is going to get hurt. And no, it doesn't just "blow out to chamber length like an Ackley", sometimes it separates and sometimes it wrecks the gun and or the shooter. Excess headspace DOES NOT CORRECT ITSELF and it is ALWAYS DANGEROUS, no matter what the cause.
There is a big, galactic difference between blowing a shoulder forward .100" with zero headspace {such as fire forming an Ackley} and having excess headspace in a chamber.
To begin with, there is zero chance you can have .100" headspace and still have the striker hit hard enough to set off the case....firing pin protrusion is typically .060". If you were to seat the bullet out far enough to hit the lands and hold the case head against the bolt now you can do it, but then you have corrected for the excess headspace...so it's not the same. That is not stretching, that is fire forming.
The idea that you can take a rimless case, "bump the shoulder back .100" so it flops around in the chamber by almost 1/8" and fire it???? Come on dude, even you know better than that.
Bottom line, if you believe you can dismiss excessive headspace this way, well...you can be the next Darwin Award recipient. Let me ask you another way...just how much headspace do you believe is safe and at what point do you believe it might start to get a little dicey????? If .100" is Okay then where do you draw the line and not shoot the gun??? Why would SAAMI bother to make the no-go gauge only .004" longer than the go gauge ????? Especially if .100" is not going to be a problem????? Isn't the word "NO-GO" your first clue?????

The OP is not talking about headspace of a gun. He was asking about his cases being new and .007 shorter then fired. This is common with new brass or factory ammo. Yes headspace on a gun can be dangerous and I did not debate this. I just stated facts of new cases and ammo. Matt

 

[LHSmith]

I get what you are saying, but factory cases that are under do not equal or are not the same as a chamber that is over sized. The one is only dangerous by and of itself, you identify and don't use until corrected...the other is a danger, no matter what ammo is used and must be corrected or someone is going to get hurt. And no, it doesn't just "blow out to chamber length like an Ackley", sometimes it separates and sometimes it wrecks the gun and or the shooter. Excess headspace DOES NOT CORRECT ITSELF and it is ALWAYS DANGEROUS, no matter what the cause.
There is a big, galactic difference between blowing a shoulder forward .100" with zero headspace {such as fire forming an Ackley} and having excess headspace in a chamber.
To begin with, there is zero chance you can have .100" headspace and still have the striker hit hard enough to set off the case....firing pin protrusion is typically .060". If you were to seat the bullet out far enough to hit the lands and hold the case head against the bolt now you can do it, but then you have corrected for the excess headspace...so it's not the same. That is not stretching, that is fire forming.
The idea that you can take a rimless case, "bump the shoulder back .100" so it flops around in the chamber by almost 1/8" and fire it???? Come on dude, even you know better than that.
Bottom line, if you believe you can dismiss excessive headspace this way, well...you can be the next Darwin Award recipient. Let me ask you another way...just how much headspace do you believe is safe and at what point do you believe it might start to get a little dicey????? If .100" is Okay then where do you draw the line and not shoot the gun??? Why would SAAMI bother to make the no-go gauge only .004" longer than the go gauge ????? Especially if .100" is not going to be a problem????? Isn't the word "NO-GO" your first clue?????

I haven't the foggiest idea of what your point is or how it relates to the Op? Attacking one of the most accomplished shooters in the history of LR BR over a basic reloading query leaves me and others baffled.

 

[BoydAllen]

If someone who is not aware of it has a rifle that has excess headspace, that is not a good thing, and may in fact be unsafe, particularly if he is inexperienced and does not know how to deal with the situation..BUT it can be successfully dealt with when using reloaded ammo. For example, just as is commonly done to make Dasher brass from 6BR, case necks can be expanded to the next size above that that the barrel is chambered for, and the case can then be sized to produce a so called false shoulder that will hold the case in position for fireforming, and prevent the case from being stretched by an amount that would damage it. After that, the die can be set for that chamber.

There is also the issue of incipient and actual separations that happen because reloaders carefully follow die manufacturers' instructions as to the proper way to set up FL dies. For example, these are the instructions that RCBS sends out with their FL dies.
http://www.rcbs.com/RCBS/media/RCBSMedia/PDFs/Instructions/English (EN)/ReloadingDieInstructions.pdf

 

[fguffey]

If you are then the formation of a 30 Herret from a 30-30 requires moving the shoulder back.

Sheepdog, I disagree, I understand the risk on this forum when disagreeing and the jagged edge that separates brilliance and belligerence.

When forming 30 Herrett cases the 30/30 shoulder does not move. The 30/30 shoulder become part of the neck, the 30 Herrett shoulder is formed from the 30/30 case body meaning the shoulder of the 30 Herrett is a new shoulder.

F. Guffey

 

[ireload2]

The shoulder is an angled surface on the case. As such it is possible to move that angled surface.
If you can't adopt the jargon of the hand loading world, you should take up muzzle loading so you don't have to be confused by the use of resizing dies being used to place a shoulder any where we want it.

Sheepdog, I disagree, I understand the risk on this forum when disagreeing and the jagged edge that separates brilliance and belligerence.

When forming 30 Herrett cases the 30/30 shoulder does not move. The 30/30 shoulder become part of the neck, the 30 Herrett shoulder is formed from the 30/30 case body meaning the shoulder of the 30 Herrett is a new shoulder.

F. Guffey

 

[fguffey]

I don't shoot factory ammo, ever. I have never measured any. As I understand it, there is a .004" range for headspace with most cartridges...says SAAMI. That is, measured from case head to datum line {in the case of a rimless rifle cartridge} so, a go gauge is zero dead on plus zero. A no-go gauge is zero minus .004".

I have to ask; "Who is the dude?". I am sure everyone understood what you just posted; but me.

so, a go gauge is zero dead on plus zero. A no-go gauge is zero minus .004

You do not measure factory, over the counter , new store bought ammo; I do and I have because I am the fan of standards and transfers. The go-gage chamber is +.005 for the 30/06 chamber. +.005"! over what? The answer is the minimum length case. the minimum length case is the same thing as a full length sized case. When a minimum length sized case is chambered in a go-gage length chamber there is .005" clearance. For those than can keep up with when the minimum length/full length sized case is chambered in a no go-gage length chamber there is .009" clearance.

Moving forward, when a minimum length/full length sized case is chambered in a field reject length chamber there is .014" clearance; meaning when the trigger is pulled the case length from the shoulder/datum to the case head will be .014" added to the length of the case from the shoulder to the case head. And then: The question is risk, now we go back to 'those that can keep up'; I Chambered a round, closed the bolt and then pulled the trigger. The shoulder of the case did not move ever though the shoulder of the case was .127" from the shoulder of the chamber (meaning there was .127" clearance and for most that is beyond what a case can tolerated before case head separation).

And the shoulder of the case did not move; back to keeping up, if the shoulder had moved I would have experienced case head separation because we all know the case can not stretch .127" between the case head and case body.

F. Guffey

I am the fan of offsetting the length of the chamber with the length of the case and my cases do not have head space.

 

[Richard Jones]

I knew I shoulda took Greek in college instead of PoliSci..........

 

[ireload2]

ob·fus·ca·tion
ˌäbfəˈskāSH(ə)n/
noun
noun: obfuscation; plural noun: obfuscations

1. the action of making something obscure, unclear, or unintelligible.
   "when confronted with sharp questions they resort to obfuscation"

 

[fguffey]

New
I knew I shoulda took Greek in college instead of PoliSci..........

"It turns out that common sense ain't all that common........"

 

[Webster]

Hi Guys,

I read a lot of comments about bumping the shoulder back by .001 or .002". Should I be adjusting my FL die to bump the shoulder back on fired cases, or on cases that have already been returned to SAAMI spec?

With my comparitor, virgin .308WIN Lapua cases and factory ammo seem to measure at 1.616", and my fired cases measure 1.623" - so am I aiming for 1.621-1.622"?

Many thanks,

Cam.

Your trying to get the proper fit to your chamber not a SAAMI spec.

 

[SheepDog]

Typically, a once fired brass is still shorter than the chamber. You don't need to move the shoulder back until it interferes with the closing of the bolt. That may never happen unless you are pushing pressure beyond the limits of your cartridge and chamber.

 

[M-61]

from SheepDog:
"You don't need to move the shoulder back until it interferes with the closing of the bolt."
+1

My opinion is it is not a required step in reloading UNLESS you experience the above.