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Old December 15, 2017, 05:12 PM   #51
Unclenick
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Ninosdemente,

Your ring question is what got you into the "ointment", but a little is good to understand in this instance. With normal pressure loads (pressures way too high can change some of what follows), your cases fatten to fill the chamber during firing, except for the solid part of the case head. The fired case then springs back elastically about 0.001", assuming it started at factory new size. When you resize, the sides of the case get squeezed down, pushing the shoulder forward. This elongation remains until the case shoulder meets the shoulder profile in the die, after which it gets extruded back, with the excess brass going into the neck (the cause of the need for trimming, though not necessarily every load cycle). The case, despite lube, usually picks up some fine marks from the sizing die, but these will go down only to where the sizing die stops or to where you run out of widened brass to push back into place. You can almost always see this pretty clearly and it is not a cause for concern. In military brass, the thickness of the head is a minimum of 0.175" from the outside bottom of the head of the case (where the headstamp is). The shell holder deck is 0.125" above that same location, so you would expect to see the end of the sizing die swaging at about 0.175" above the head or higher, depending where the brass profile's wall thins to where the pressure ring forms.
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Old December 16, 2017, 09:14 AM   #52
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When you resize, the sides of the case get squeezed down, pushing the shoulder forward. This elongation remains until the case shoulder meets the shoulder profile in the die, after which it gets extruded back,
A reloader can shorten the distance between the shoulder of the case and case head, the reloader can not move the shoulder back; when sizing and forming a case the shoulder the reloader starts with is not the same shoulder he finishes with.

Proof? I am the only reloader that has scribed a case; In my opinion the best place to scribe a cases is at the shoulder/case body juncture. When I fire a case the shoulder on my cases do not move, the nice thing about that is: The shoulder on my ejected case is not the same shoulder I started with.

And then there is the confusing part; If the firing pin drives the case forward the case has no choice but to stretch between the case head and case body.

One more time: I have fired cases in one of my chambers with .127" clearance between the shoulder of the case and shoulder of the chamber. after firing I ejected the cases with my original shoulder .127" behind my new fire formed shoulder. And the neck? The short neck was proof my original shoulder did not move forward because it was very short.

I could ask: Where did my shoulder go? My original shoulder did not move, it became part of the case body and the neck of the case became part of the shoulder.

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Old December 16, 2017, 11:37 AM   #53
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Originally Posted by USSR View Post
Don't recall any "theory" being imparted here, just the mechanics of what is taking place as you resize a case. Big difference between tuning a car wrong where the car doesn't run, and reloading a case that has to contain a 60,000 psi explosion just inches in front of your face.

Don
On forums, when I reply to basic questions, I reply as if I were talking to an absolute new beginning reloader. And sometimes a self appointed expert will pick my posts apart, word for word. So, I bow to The Firing Line's new, Most High Everything Reloading expert, and will leave this thread, genuflecting as I back out...
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Old December 16, 2017, 01:15 PM   #54
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I feel the same , but I roll with the Punch's , some of it is way over my head . Cases are cases to me others list it as different mixtures of materials . Headspace , tensions all I'm looking is a 3rd grade answer to the question an there is one. Some like to add much more. Hang in there mikld.
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Old December 16, 2017, 06:18 PM   #55
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On forums, when I reply to basic questions, I reply as if I were talking to an absolute new beginning reloader. And sometimes a self appointed expert will pick my posts apart, word for word. So, I bow to The Firing Line's new, Most High Everything Reloading expert, and will leave this thread, genuflecting as I back out...
Aw, we will miss your cheap shots, mikld.

Don
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Old December 17, 2017, 12:06 PM   #56
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No russia, I ain't leaving, just tired this thread...

BTW; my shots ain't cheap, they are well aimed sarcastic replies to inflated egos...
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Old December 17, 2017, 06:28 PM   #57
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Whatever you do mikld, DON'T click on this link - You will have a stroke.

Don

https://thefiringline.com/forums/sho...d.php?t=591942

Since the above post which contained a pic of a newpaper article in it has been closed by management, I will just say it was a very complimentary article about the Metallic Cartridge Reloading Course I teach.
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Last edited by USSR; December 17, 2017 at 08:40 PM.
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Old December 17, 2017, 09:02 PM   #58
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Aw, we will miss your cheap shots, mikld.
From my take he reflects my often confused reading of Mr Guffy.

I mostly skip over it. I assume I am denser than depleted uranium, otherwise I would get it.

Like mlkd I believe simple answer are better answer (knowing that sometimes simple is relative). Maybe the simplest answer is the best answer.

As being dense, I am often confused and simple works better for me. As the questioner would not be asking if he knew all that, then I sort of lean to simple. I can remember being confused. But then I can remember shades of 2 to 4 years old as well. Maybe its my inner wounded child trying to help?

And philosophically , do not all reloaders have a stroke? (or is that to stroke, thinking about the bard, to stroke or not to stroke, that is the question)

Granted there can be some discussion as to weather Mohammad went to the mountain or the mountain went to Mohamed.

In this case (pun intended) did the shoulder move or did the back of the case move?

I think I am a shoulder moving kind of guy, as we reference from the back of the case for much, it would at least be a good mental model (or a base of reference, another pun of course)
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Old December 17, 2017, 09:06 PM   #59
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And then there is the confusing part; If the firing pin drives the case forward the case has no choice but to stretch between the case head and case body.
Well seeing as how the firing pin dents the primer and while the case may move (depends on how the case fits the chamber me thinks and bench rest shooters like to have to cam the bolt), it also absorbs some or all of the firing pin forwarding.

And as here is a great deal of pressure extreme, said case will then drive back into the firing pin if it does move per most of our reloads.

the solid parts are the shoulder of the chamber, the chamber walls and the bolt head itself (though in fact its the lugs of the bolt that fix the bolt head in place).
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Old December 18, 2017, 09:15 AM   #60
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It's hard to imagine all the little contributors at work. Ever noticed that after firing a low-pressure load you eject a case with the primer high, even though it wasn't high originally? Indeed, firing wax bullets by primer power alone will jam rotation of a revolver's cylinder with the backed out primers if you don't first drill the flashholes out to about 1/8". So, in addition to the firing pin pushing the case forward before the pressure gets too high, the primer itself assists the case going forward by its own pressure forcing it out of the of the pocket and back against the breech.

We know this stuff happens both because the military has used angled mirrors looking down a muzzle to measure bullet movement throughout the firing event with high speed precision laser rangefinders and because of case growth and head separation at higher pressures. If the cases were not pushed forward before pressure grew enough to stick the brass to the chamber wall, the stretch in the brass would not occur at the pressure ring. It is due to the subsequently developing greater pressure pushing the head back against the breech while the rest of the case remains stuck in its forward position. If instead, the case stayed to the rear against all these forces, the shoulder would blow forward but no pressure ring thinning would occur and no case growth would occur because the extra brass filling out the shoulder would draw it from the neck and resizing would merely put it back again.

So, the physical evidence is there. If you look at complete traces of chamber pressure that start at firing pin impact, they develop a low primary hump or ledge before the main pressure build-up begins. That's the primer pressure. It happens first and fastest, setting the pressure conditions needed for powder burn, and then the powder burn gets underway in earnest. This is why, in small capacity cases, a primer can unseat a bullet before the powder has enough pressure to do so. Powder doesn't ignite instantly.
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Old December 18, 2017, 09:36 AM   #61
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As always , very good post .
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Old December 18, 2017, 09:58 AM   #62
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So, the physical evidence is there. If you look at complete traces of chamber pressure that start at firing pin impact, they develop a low primary hump or ledge before the main pressure build-up begins. That's the primer pressure. It happens first and fastest, setting the pressure conditions needed for powder burn, and then the powder burn gets underway in earnest. This is why, in small capacity cases, a primer can unseat a bullet before the powder has enough pressure to do so. Powder doesn't ignite instantly.
I remember the old story about the firing pin, it went something like "the firing pin drives the case, bullet and powder forward until the shoulder of the case contacts the shoulder of the chamber etc. etc." And I asked; "How can that be, my firing pins crush the primer before the case, bullet, and powder know their little buddy, the primer, has been hit. And then I said the worst thing that can happen is for the shoulder of the case to be setting at the shoulder of the chamber when the case is hit with all of that pressure.

Clearance: Again, I have fired cases with .127" clearance between the shoulder of the case and shoulder of the chamber, no miracle, my shoulder did not move, had my shoulder on my cases moved the case would have had case head separation; there was a down side, the .127" clearance shortened my case necks and because my shoulders did not move the length of the case from the shoulder to the case head lengthened.

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Old December 20, 2017, 12:13 PM   #63
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Whenever I answer a basic question on a forum, I aim it towards a new reloader (if the OP isn't a new reloader, why would he ask basic questions). Many of the "Reloading Gurus" on forums quickly get into advanced reloading techniques and theory and can cause "information overload", confusing a new reloader. Having taught complex diagnostics and most of the time to mechanics with very little electronics/electrical knowledge I have found K.I.S.S. teaching is by far best for the student. Same with reloading...

Maybe if I posted pics of my diplomas and certificates and expounded on my expertise, I'd be accepted? Nah, who cares?

Nuff said...
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Old December 20, 2017, 03:17 PM   #64
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Another scattered,disconnectd,confuzing whizzing contest to answer the OP's simple beginner question.

OP,there are degrees of precision. It has to be "good enough" to get good,safe results. There is more than one way to get there,and more than one level of acceptable results.
Worst is working blind,with no standard. !/4 turn of your die is approx. .018. We'd like to work closer than that.
Over time,you may want to pursue whatever the "ultimate" is for setback,or more correctly,"head clearance". The often quoted number for a bolt gun is .002. That's nice,and you can do it.
You already have two fine,useful standards. One is your rifle. Its a bit clumsy to use,but it is the last word.

The other is your case length bushing gauge. You said you have one. Read the directions. Do you see the Hi/Low step? If you size your brass so a straight edge shows you between those steps,your brass is SAAMI spec,and good enough to be a factory load. You CAN leave it at that. In any case,you need to learn the paper clip probe trick,and monitor your brass for stretch rings.You now have a good,workable standard.If you have more than one rifle,the ammo ought to work.This would be the K>I>S>S> method with the tools you have(assuming calipers)

If you want to refine this a bit,no problem. There are several ways.Here is one good one that does not demand $. Use your bushing gauge,start a little long,and advance the die 1/32 of a turn (just about .0025 ) at a time.Find the spot where your brass just closes in the chamber with no crush.
Now,drop that case in your bushing gauge and measure over the bushing die and cartridge case assembled. Subtract .002,and write that number inside your die box with a sharpie.
From now on,set that die to that rifle by hitting that measurement over the gauge and case. Note,if your brass needs trimming,it will stick out and mess this up.

Now,your original question. I had a similar "Aww,Do-Do-" moment.I bought a brand new Elliot 30-06 AI reamer AND sprung for the floating reamer holder.
Built the rifle and fired it. Rings,more pronounced than yours. AhhhrggH!!

With gauge pins,I measured the chamber. I mic'd the reamer. Same size. Floating holder worked good. I checked chamber drawings. Right on.

I measured cartridge cases against the drawing for the 30-06 brass. All of it was .005 undersize.

In other words,no worries. Yours look good.

Do get you brass clean before you size

Last edited by HiBC; December 20, 2017 at 03:38 PM.
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