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 Less headspace on a once fired round..How?
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Ireload2
Senior Member

USA
286 Posts

Posted - Oct 29 2016 :  02:36:39  Show Profile Send Ireload2 a Private Message  Reply with Quote

How the case behaves when fired depends on the pressure level, hardness of the brass,the size of the chamber compared to the brass and maybe even if your bolt has a plunger ejector.

When the cartridge is fired the pressure expands the case like a balloon until the case is constrained by the chamber. If the chamber is significantly larger in diameter than the case the case will get shorter when fired. This is easily measured. If you have a plunger ejector and low pressures and maybe brass with a lot of internal stress it is possible that you might see the shoulder move back.
With low pressure loads sometimes the primer backs out and keeps the case pushed forward in the chamber. You can find the backed out primers mostly on .30-30 and .35 Rem factory once fired cases.
A plunger ejector can also help push the loaded round forward. You can sometimes find backed out primers from .30-06 ammo fired in 700 Remingtons and similar actions.

When you resize your case even though you stuff it in a die the shoulder can move forward as the die contacts and squeezes in the case body. If your die is not set properly you can push the shoulder forward and make chambering difficult.

There are several ways to deal with cases that do not FIRE FORM completely. I will name a few without regard to a specific set of operations to complete the process.
1. Load with higher pressure if your loads are too light. Just make sure you understand that low pressure is the REAL problem if you use this.
2. Annealing the neck and shoulder to a point about 1/4" below the shoulder will enable the case to better take the shape of the chamber on the first shot.
3. Multiple firings can eventually blow the shoulder out to the full length of the chamber.
4. Removal of a plunger ejector might help.
5. A coarse or rough chamber surface texture may keep the cases from sliding back when fired.
6. I am not recommending this but I have applied a light oil film to formed cases before they were fired to help them fire form. The oil film helps the case slip back to the bolt face while expanding. But like I said it is not recommended for those that do not understand when and how to use the method or how it works.

I have fire formed cases that I constrained 3 different ways when fired.
1. Shoulder hard against the chamber shoulder
2. The case neck was left too long for a Mauser 7.65 chamber. Argentine Mausers have a 90 degree shoulder at the end of the case mouth in the chamber. This shoulder is very prominent and I head spaced the brass against the shoulder with the case mouth just like a .30 Carbine or .45 ACP head spaces.
3. The bullet was seated long and made hard contact with the lands when the bolt was closed.

The results of the above? The cases got shorter when fired. Because I did not use high pressure loads some of the primers still backed out .001 to .002.















No one is here for a lesson in Guffey style semantics.
You have been criticized before for your incorrect use of tension vs pounds yet you can't seem to admit that you are talking about measuring a tensile force. If you insist in being wrong why do you give others a hard time? Take a class in engineering mechanics called statics and correct some of your own faults.







quote:
Originally posted by F. Guffey

quote:
Need a little advice,



ruthless4645, you ask for a little advise; in my opinion that is all you got, a little, very little.

First, your case does not have head space and the tool your are using is not a head space tool. I know, reloaders believe everything has head space and all tools are head space tools.

F. Guffey




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Ireload2
Senior Member

USA
286 Posts

Posted - Oct 29 2016 :  02:49:25  Show Profile Send Ireload2 a Private Message  Reply with Quote
I will offer you a little advice too.
As Guffey's sycophant you encourage his negative behavior.
I would agree with the other posters. No only did Guffey add nothing positive he made an enemy - probably permanently.
No one tried to piss off Guffey. No one even addressed him until after he made his usual worthless comment. If Guffey is getting pissed off over terminology he probably should stay away from the board because many times he says NOTHING constructive other than spewing Guffy STYLE semantics.....

Now if Guffey's behavior is acceptable to you then you will not mind me using the same form of crypto babble to criticize and correct both you and Guffey in the future while not offering the least bit of constructive input. Isn't his wonderful style good enough for everyone to use against each other? I would prefer posters not behave in that manner nor tolerate it either.



quote:
Originally posted by WonderMan4

Well, for another one, I happen to agree with Mr. Guffey in that only a chamber has headspace.

You say he offered nothing, well, I beg your pardon, he offered you the correct terminology.

The measurement that you are referring to is called Cartridge Base to datum. It is not headspace. Headspace is measured from the bolt face.

I think it is typical for a cartridge to expand when fired and then shrink when the brass relaxes. If you use a comparator, you can see the difference on each cartridge that you fire in any caliber.

YOu may not like his style, but he is a wealth of knowledge. And here you are trying to piss him off right at the start.


Edited by - Ireload2 on Oct 29 2016 02:55:28
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Onondaga
Advanced Member



USA
4017 Posts

Posted - Oct 29 2016 :  06:21:43  Show Profile Send Onondaga a Private Message  Reply with Quote
You haven't lost any head-space. What happened is that you noticed what happens to brass when you fire it.

Even if the same thing happens with new brass, it is inconsequential as the new brass fired in your rifle is fire-formed every time you fire it. If your numbers were larger it still would not be unusual. You get what you get when you fire them.

If you Lee collet neck size, that die cannot change the datum point on your brass. If you FL size, you can debate where you wish to adjust your setback by FL sizing.

Gary

Fine rifles are never really owned.
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 29 2016 :  09:46:58  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
Really an unusual result. I reload for over 40 different rifles and, like you said, the shoulder moves forward during firing. Usually until you get a crush fit and have to move the shoulder back slightly to facilitate chambering.


If the shoulder moves forward when fired the case stretches between the case body and case head. And no, this is not unusual; it is a matter of a reloader using bad habits. I know, it sounds cute to use reduce loads.

I form cases and I fire form cases, when I fire form cases there is nothing about the case getting short that is considered normal. I am talking from the shoulder to the case head. I fire form cases that shorten .045" from the mouth of the case to the case head. I do not have cases that shorten from the shoulder to the case head. And one more time; if the shoulder moves forward the case has already started to separate between the case body and can case head.

quote:
How is that possible?, how did I lose headspace length, I always thought the case became larger through fire forming not smaller.


I have always said there is something that happens between pulling the trigger and the bullet leaving the barrel reloaders do not understand. There is a very prolific poster on many forums that has always claimed the firing pin strikes the primer and the whole thing, the bullet, case and powder take off for the front of the chamber and stops when the shoulder of the case hits the shoulder of the chamber. I have always said I have killer firing pins, my firing pins crush the primer before the case, powder and bullet know their little buddy the primer has been crushed. Again: I said I have fired cases in chambers with .127" clearance. If the shoulder collided with the shoulder of the chamber before the powder went bang all of my cases would have suffered case head separation because we all know there is no way to stretch a case .127" between the case head and case body.

And then there is that other set of circumstances. That would be when I form a case and the case does not get longer from the shoulder of the case to the case head or by some miracle the case gets shorter from the shoulder to the case head.

F. Guffey

quote:
How is that possible?, how did I lose headspace length, I always thought the case became larger through fire forming not smaller.


Again, the case does not have head space. I off set the length of the chamber with the length of the case, I am the fan of cutting down on all that case travel.

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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 29 2016 :  09:58:25  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
You haven't lost any head-space. What happened is that you noticed what happens to brass when you fire it.

Even if the same thing happens with new brass, it is inconsequential as the new brass fired in your rifle is fire-formed every time you fire it. If your numbers were larger it still would not be unusual. You get what you get when you fire them.

If you Lee collet neck size, that die cannot change the datum point on your brass. If you FL size, you can debate where you wish to adjust your setback by FL sizing.


His case got shorter from the shoulder of the case to the case head, I do not doubt that, he wants to know why it got shorter, again, I have always said there is something about the sequence of events that happen between pulling the trigger and the bullet leaving the barrel reloaders do not understand. I say 'BAD HABITS' I say a lack of discipline. When I fire a case I fire a case, I do not sneak up on it, there is nothing timid about my loading, when I fire to form I do it once, I know it sounds cool to use toilet paper, cereal, pistol powder etc. So if you are going to fire a case to form it; FORM IT!

F. Guffey
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Leatherstocking
Average Member

Canada
141 Posts

Posted - Oct 29 2016 :  11:25:26  Show Profile Send Leatherstocking a Private Message  Reply with Quote
Then set up your full length sizing die and see if it sizes back to the factory dimension.

So Shasta, do you use the smoke or ink method to set up the FL die? Or is there a way to measure shoulder clearance without measuring case base to datum?
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 29 2016 :  11:31:27  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
And then there is the claim reloaders move the shoulder back and forth. they also claim the shoulder of the case moves forward when fired and then we go back to reloaders not understanding the sequence of events between pulling the trigger and the bullet leaving the barrel. The shoulder moving forward when fired is the results of bad habits and misunderstanding the sequence of events;

One more time, I find it impossible to bump the shoulder back on a case when sizing because the shoulder on my cases when sizing does not move.

And then there is the 'again'. I can not move the shoulder back on a case with case body support I can shorten a case from the shoulder to the case head by moving the shoulder back but I can not do that with case body support. When I size a case without case body support I upset the shoulder/case body juncture, after that the case begins to fold like an accordion the then the case starts to become a bellows. BUT! When sizing a case the reloader claims he bumps the shoulder, again; I find that impossible and it leads me to believe the reloader has not clue about what is happening when he sizes a case.

F. Guffey

Edited by - F. Guffey on Oct 29 2016 11:33:51
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 29 2016 :  11:52:25  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
Leatherstocking,

quote:
So Shasta, do you use the smoke or ink method to set up the FL die? Or is there a way to measure shoulder clearance without measuring case base to datum?


This is a reloading forum, members of this forum have presses and dies. A reloader with a press and die with threads should have the ability to size a case. Again, anyone with a press and die should be able to shorten a case from the shoulder to the case head and then there are cases that are short from the shoulder to the case head. My favorite cases are cases that are too long from the shoulder to the case head. My favorite cases are the ones that will not allow the bolt to close when chambered. Even then. when the bolt will not close I know by 'how much'. A reloader should know much sizing is required to allow the bolt to close.

I know, reloaders claim they move the shoulder back and I claim the shoulder does not move.

quote:
quote:
The headspace length on an UNFIRED cartridge measures 1.770" using my Hornady headspace gage (insert #375).



Insert #375? The #375 should be the datum .375", problem, the insert for the .375" datum has a radius. Time and time again I have said the datum can not have a radius, I use datums that are not case friendly. The radiys turns the tool into a comparator because the reading is not accurate. Again, I am the fan of standards, transfers and verifying, an insert with a radius is not a standard, transfer and to verity the tool the reloader must have a standard to verify.

F. Guffey


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Shastaboat
Advanced Member



USA
9122 Posts

Posted - Oct 29 2016 :  12:22:50  Show Profile Send Shastaboat a Private Message  Reply with Quote
quote:
Originally posted by Leatherstocking

Then set up your full length sizing die and see if it sizes back to the factory dimension.

So Shasta, do you use the smoke or ink method to set up the FL die? Or is there a way to measure shoulder clearance without measuring case base to datum?




Most of the time I lube a fired case and then smoke it with wooden matches or a candle. Then I set my full length sizer to just kiss the shoulder. My loaded ammo may not chamber in another weapon that has a tighter chamber. That is not my problem, it would be the owner of that weapon. For any calibers that I have multiple weapons then I generally full length, cam-over size and set my dies appropriately. About the only caliber I have that issue is .223/5.56 and now I'm loading all my ammo on a progressive press for that caliber and making sure it chambers in my AR15. I don't have any case length gauges or case shoulder gauges. My gauges are my weapon's chambers. I use a caliper and trim to my desired size if necessary.

Edited by - Shastaboat on Oct 29 2016 12:26:20
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 30 2016 :  11:09:02  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
The results of the above? The cases got shorter when fired. Because I did not use high pressure loads some of the primers still backed out .001 to .002.
So 'basically' you do not know what happened or why.

You did not fire form the case if the case did not fill the chamber; you went through the motions. And now we are back to where this thread started with the OP asking 'how could this happen'.

I have fire formed cases that shortened .045" from the mouth of the case to the case head. Again, the shoulder did not move when I formed the case and the shoulder did not move when I fire formed the case. Had the shoulder moved I would have been wasting my time.

F. Guffey
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 30 2016 :  11:14:47  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
5. A coarse or rough chamber surface texture may keep the cases from sliding back when fired.


I want 100% contact between the case and chamber; when the case locks onto the chamber 100% contact is better than 70%, I want a mirrow finish. I also want nothing between the case and chamber but air, not a lot of air but the air that is there I want it to be clean.

F. Guffey

Edited by - F. Guffey on Oct 30 2016 11:15:43
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Oct 30 2016 :  11:26:15  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
2. The case neck was left too long for a Mauser 7.65 chamber. Argentine Mausers have a 90 degree shoulder at the end of the case mouth in the chamber. This shoulder is very prominent and I head spaced the brass against the shoulder with the case mouth just like a .30 Carbine or .45 ACP head spaces.


I would suggest a seating a case with a long neck against the end of the chamber is a bad habit.

NFL: as in 'not for long', hot high pressure metal cutting gas will take care of the sharp edge. That leaves the reloader 'wanna-be fire former crimping the bullet when chambering the round.

And then there is the absence of forming dies. I form 7.65mm53 cases from 30/06 cases. I form 7.65mm53 cases and then fire them. It is not necessary to fire form. A fire former is not required to know anything more than how to pull the trigger; meaning they pull the trigger and they become fire formers.

You fire formed cases, the case got shorter and you do not know why.

F. Guffey
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noylj
Advanced Member



USA
553 Posts

Posted - Nov 01 2016 :  16:51:42  Show Profile Send noylj a Private Message  Reply with Quote
>on the SAME case after I've FIRED it I consistently get a measurement of 1.768"........How is that possible?

Re-measure after sizing.

Then said he unto them; But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one.
Luke 22:36
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F. Guffey
Advanced Member

USA
961 Posts

Posted - Nov 06 2016 :  11:18:04  Show Profile  Visit F. Guffey's Homepage Send F. Guffey a Private Message  Reply with Quote
quote:
Re-measure after sizing.


I agree I would go one step further and suggest the reloader measure the length of the case from the shoulder to the case head before firing and again after firing. In my opinion it is one short step from measuring after firing and again after sizing.

With a little discipline a reloader could eliminate the excessive use of the word head space. To accomplish that the reloader should understand the use of a comparator; the comparator is not a head space gage, using the word ‘head space’ in the description places the phrase at the top of GOOGLE SEARCH. I understand that makes no sense to most but sellers of tools that are not head space tools get top billing when a reloader is searching for a tool they do not understand.

Back to the top: The case does not have head space, when a reloader measures the length of a new case from the shoulder of the case to the case head they should use the measurement to comparing the measurement to a fire case. The difference in length between the two cases should indicate the effect the chamber had on the case when fired.

And then there is the mindless part; if there is a difference in length between the new and fired case when measured from the shoulder to the case head the reloader should understand what the difference in length means. AGAIN: I have a 30/06 M1917 that has a chamber that is .002” longer than a field reject length gage. That is .014” longer than a new, factory, over the counter SAAMI minimum length/full length sized case. For me that is not a problem, I adjust the full length sizing die .014” off the shell holder then size/neck up 280 Remington cases to 30/06 cases. Unless I lost someone by adjusting the die off the shell holder .014” I got the magic .002” clearance without fire forming the case.

And then there is that part that that is almost impossible to grasp; I could use new 30/06 cases to form cases for that rifle. Problem (my opinion); the cases when ejected would be found to be short from the mouth of the case to the case head.

F. Guffey
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Zero333
Advanced Member



Canada
810 Posts

Posted - Nov 06 2016 :  18:49:00  Show Profile Send Zero333 a Private Message  Reply with Quote
Deprime the fired brass before taking the Headspace measurement.

Treat that trigger like it’s your first date, not like you’ve been married to it for 20 years.
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