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Old February 8, 2018, 04:53 PM   #26
F. Guffey
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I and most everyone here could give two craps about datums and your exclusive rights to them.

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Short SAAMI
.470" .468" rim diameter
.338" .337" rear neck
.442" .441" rear shoulder
.453" .450" mid case dia

I have no ideal what there is about datums that makes so many reloaders feel threatened. Again, the datum is not a line, it is a circle, it is a round hole. You should be able to measure the diameter of your cases in thousandths with an absolute distance from the head of the case or from the shoulder of the case etc.

It is not my fault you can not.

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Old February 8, 2018, 06:39 PM   #27
Yosemite Steve
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Guffey, go troll somewhere else.
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Old February 9, 2018, 07:17 AM   #28
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Actually, Mr. Guffey,

A "datum" CAN be a line (or a point, or a surface, etc)....

It is any point of reference for measurement, not a shape. In context with brass, it can be the rim for a rimmed cartridge, the case mouth, belt, or midpoint of the shoulder (as being discussed here).
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Old February 9, 2018, 08:50 AM   #29
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Actually,
I do not make excuses, SAAMI furnishes datum information in diameters. The 30/06 datum diameter is .375", it is too bad a reloader looks at the location of the datum of the chamber and case drawing from the side. I gave up on trying to get a reloader to think in dimensions as in from the side, front and top.

Most reloaders have not moved beyond the arrow pointing at a line and then identifying it as the datum line. And I said it was not a line, I said it was a round hole/circle.

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Old February 9, 2018, 12:31 PM   #30
Yosemite Steve
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It's good that you know what a datum is... it sucks that you but into every thread with it. The numbers i gave were just examples of various diameters to show differences in expansion. I don't really feel like the datum was relevant to what I was talking about. It was a shorter chamber. How much shorter did not matter to me at the moment.
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Old February 9, 2018, 11:18 PM   #31
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My datum measurement for my cartridge is 2.0475 where the bolt handle begins to feel the cartridge with nothing on the bolt but the bolt head and handle. I know it's on the shorter end of the tolerances and will not accept my partial sized brass from before. Even though it's on the small end it should accept any factory 30-06 cartridge now right? Also is that where I should size my brass or should I go for .001" shorter?
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Old February 11, 2018, 08:43 AM   #32
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Now my question is this: The brass that I resized for when I had the short chamber is .016" short of filling the chamber. It takes 4 pieces of masking tape on the head before it can be felt on the bolt handle closing the bolt with no firing pin or ejector. The tension is very light but it is there. I removed the 4 layers of tape in one piece and it measures .016" thick. Is the brass too short to use again or can it be fire formed back to usefulness? It's Nosler brass and wasn't cheap but I don't want to risk any safety.
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Old February 11, 2018, 10:26 AM   #33
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Load it, shoot it, and measure it to set your size die. There is nothing that will prevent it from forming to the chamber. Some folks refer to this as fire forming.
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Old February 11, 2018, 11:49 AM   #34
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I understand. But the shoulder was set back and I was worried about the headspace being too much.
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Old February 11, 2018, 12:39 PM   #35
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Originally Posted by Yosemite Steve View Post
Now my question is this: The brass that I resized for when I had the short chamber is .016" short of filling the chamber. It takes 4 pieces of masking tape on the head before it can be felt on the bolt handle closing the bolt with no firing pin or ejector. The tension is very light but it is there. I removed the 4 layers of tape in one piece and it measures .016" thick. Is the brass too short to use again or can it be fire formed back to usefulness? It's Nosler brass and wasn't cheap but I don't want to risk any safety.
0.016" head clearance is too much for my liking. For high power rifle I won't shoot more than 0.008”, 2 layers of masking tape.

If you still have unsized brass left, start using them and set aside the short brass. If you don't, then you will need to fire form the short brass with light loads back to fit the current chamber.

If you have only one rifle to load for, it is pretty simple really. You don't need gauges, datum, or any of that sort. Just screw in the die, size, and test, till the action closes with minimal head clearance. 0.002" for bolt action and 0.004" for semi auto. Bear in mind the die body thread is 14 tpi. Each turn is 0.071", 1/4 turn is 0.018".

Hope this helps. I have been handloading more than 20 calibers for my pile of milsurps junk. I don't have a single piece of gauge. I get 20 loads out of each batch of brass on regular basis.

But occasionally I will yell at the top of my lungs... Datum!!!

-TL

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Old February 11, 2018, 03:59 PM   #36
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Welp. I have 47 of them. I can use them for fouling shots. I will measure them as I go if I do. The R P and Winchester brass I have should keep me going for quite a while.
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Old February 11, 2018, 05:10 PM   #37
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Now my question is this: The brass that I resized for when I had the short chamber is .016" short of filling the chamber. It takes 4 pieces of masking tape on the head before it can be felt on the bolt handle closing the bolt with no firing pin or ejector. The tension is very light but it is there. I removed the 4 layers of tape in one piece and it measures .016" thick. Is the brass too short to use again or can it be fire formed back to usefulness? It's Nosler brass and wasn't cheap but I don't want to risk any safety.
You're jumping around here...
"for when I had the short chamber"... Last I read, you changed the bolthead, and ended up 8 thou short on headspace. Then, you ground your shell plate to jury rig the sizing die to the non-standard dimensions (I would never modify a shellp!ate or die by that much...couple of thou at most).

Did I miss the part where you had the chamber reamed to the correct depth to headspace properly with the new bolthead?

And btw...be sure your health/life insurance is current before you decide to pull the trigger on a .30-.06 round with .016 of air between it and your boltface.
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Old February 11, 2018, 06:19 PM   #38
Yosemite Steve
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And btw...be sure your health/life insurance is current before you decide to pull the trigger on a .30-.06 round with .016 of air between it and your boltface.
Yeah I have been going over that in my head.

Quote:
Did I miss the part where you had the chamber reamed to the correct depth to headspace properly with the new bolthead?
You must have. The lugs were lapped and bolt face shaved down. It is a go! I can not afford any further gunsmithing at this point. Next time it will be re-barreling. I can get an identical unfired take off for $85.
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Old February 18, 2018, 11:08 AM   #39
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Using a hammer and a 9mm case I was able to make my own datum line reference tool. It is not at .375 but it does give me consistent shoulder reference measurements.

Going back to where I had sized my Nosler brass to fit the chamber of my gun (when the chamber was shorter and the lugs were not lapped and lopsided) by grinding my shell holder back, those cases when fired gained in case head to (my) datum length by .013" on every one. At the same time those cases gained in total length from case head to end of neck by .007" to .009". Those that were shot are still .004" short of filling the chamber from bolt face to chamber datum.

My un-fired short sized cases are .017" short of meeting the length to fill my chamber end to end.

What I am getting from this information is that the .010" taken off the shell holder was too much. The bolt head being put on incorrectly and not having it's bevels cut into the lugs at the time were probably the equivalent of .004" of headspace when the gun was fired the brass expanded and (maybe) shrunk back .001". The necks gained between .004" and .006" in length so the case behind the shoulder had to have stretched between .007" and .009". This was twice fired Nosler brass. As much as I would not like to loose it I think it should go in the recycle bin.

Moving forward... I have yet to purchase a new shell holder. .010" was ground off. If I set it so that a .012" feeler gauge will snugly slide in between the shell holder and the base of the die my sized brass fits my chamber end to end with no play. I have seen where people say to give .001" to .002" play. Why? Won't that tiny bit of play allow the case to drop just slightly costing a smidge of accuracy? I have also read that to have the shoulder just touching is better. My ejector pin pushes the case to the shoulder of the chamber so the gap will always be at the case head. The firing pin cannot move the case forward more but when fired it will still slam back against the primer. I believe this is the cause of my flat primers. Question is how much headspace will cause a flat primer?
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Old February 18, 2018, 12:36 PM   #40
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And btw...be sure your health/life insurance is current before you decide to pull the trigger on a .30-.06 round with .016 of air between it and your boltface.
Yeah I have been going over that in my head.
You need to read up on fire forming. No need to toss 47 perfectly good Norma brass cases.

If you need guidance, let me know.
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Old February 18, 2018, 12:47 PM   #41
Yosemite Steve
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I'm all ears!
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Old February 18, 2018, 02:53 PM   #42
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You need to read up on fire forming. No need to toss 47 perfectly good Norma brass cases.

If you need guidance, let me know.
Sure thing. Post it up! There is a reason Saami has headspace specifications.

Explain the limitations of the brass thinning/stretching far beyond what's intended...if .016 of air isn't a problem- at what point does it become one? .020? .030? 1/4"?

Even if it WERE safe- and I am not in agreement that it is- the brass would need to be segregated, separate load workups, and separate neck-size only. Might as well own another rifle.

All for a few pieces of brass....
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Old February 18, 2018, 02:55 PM   #43
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I started doing it like this back in the early 70s and then Sierra wrote an article on it.

The link to Sierra's fire forming instructions written by Duane Siercks.

https://sierrabulletsblog.com/2016/0...forming-cases/

Don't let the 0.016" short cases set you back. Follow the instructions.

I have used H4895 & IMR4895 in the 30-06 with 150 gr and 165 gr bullets.

tobnpr, I don't know what your experience levels are, but you are spouting information that is not warranted.
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Old February 18, 2018, 03:32 PM   #44
Yosemite Steve
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That is the article I just finished reading. :P

Everyone is entitled to their opinion. Tobnpr has a good point in that now, in order to fire form the brass I must do some things. Is it worth the effort? 47 rounds of bullets + 47 primers + 47 powder charges + extra time and care given to reloading + going to the range and shooting + going back and taking extra time to carefully inspect the brass = $25 and 4 to 6 hours. Cost of new brass $50.

VS.

Something to tinker with + learn something in the process + use that experience to help load more accurate ammo in the future.

The question for me is this? How big of a strain is the brass taking from this? It was fire formed once, reduced by .016" at the shoulder and will now be pushed back to it's original fire formed dimensions. I can see no warning signs on the brass that was fired that pushed the shoulder forward .013". Annealing is not an option for me at this point as I do not have a reliable scientific method to do so.
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Old February 18, 2018, 03:41 PM   #45
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When I was wildcatting in the early to late 70s, I probably fire formed at least 3,000 cases with not one problem.

Millions of brass cases have been fire formed by many experimenters over the years.

It is a safe and economical process when performed properly and with all applicable safety practices.

Sometimes, as mentioned in the second sentence, it is the only way you are going to get suitable brass for your projects.

I have never, and will never, used cream of wheat.

Use of cast bullets is another viable means of completing the task when jammed approximately 0.015" into the lands.
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Old February 18, 2018, 04:46 PM   #46
Yosemite Steve
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Explain the limitations of the brass thinning/stretching far beyond what's intended...if .016 of air isn't a problem- at what point does it become one? .020? .030? 1/4"?
My understanding is that if I seat a bullet to the lands the case cannot be pushed forward when fired where it would then form to the chamber and stretch backwards towards the base. Would the brass then stretch towards the shoulder or would it simply reform itself to the shoulder of the chamber or both?
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Old February 18, 2018, 05:12 PM   #47
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Holding the case against the bolt face is the only way fire forming will work for me.

Since your brass is already somewhat conformed to your chamber, the brass will flow forward 0.016" and form a new shoulder.

When manufacturers make brass, they, in a sense, hammer forge the brass and then press into forming dies so to speak.

Sizing down is always better than forming up, but both work and both have been done this way for many years by many people, myself included.

As previously mentioned, check the cases for internal stresses. A bore scope is ideal for this, but the pick or paper clip trick works satisfactorily. You could even take your method of testing to the range with you and check the first few right after firing.

If you have a rifle with a freebore (I know from earlier posts that you do not), then you might be hosed and have to use other measures. That is when I prefer to use long cast bullets. Some would use the cream of wheat method. I think HiBC (I may be mistaken on who did) has posted earlier on this method.

I make my own molds for the long cast bullets so it is not a problem for me.
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Old February 18, 2018, 05:13 PM   #48
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tobnpr, I don't know what your experience levels are, but you are spouting information that is not warranted.
I don't believe I "spouted" anything incorrect.
I read your linked article, it's about fireforming.

This isn't at all about simple fireforming- I'm no expert in internal ballistics- but that much is sure.

The OP TRIMMED a ton of brass, from cases that were too long to headspace within tolerance to his rifle.

That brass won't miraculously regenerate when it's fired in a now-spec rifle. It's lying next to his case trimmer- and it's not coming back.

So where does the extra length, after the case is fired again, come from?

The casehead- which will now be thinner than before.

How much? You're the expert- tell me. What's the equivalence to brass life/material lost through shooting/ resizing cases in normal processes?

Even if only neck sized from here,, the casehead will still stretch more, the cases will still keep stretching, and they'll still need to be trimmed eventually. More brass lost, from a casehead that had already been thinned prematurely by what was done to it.

You can only thin a casehead "so much", before it separates. Now, if anything I've just stated isn't fact- be specific and point it out, explain why.

This isn't like fireforming to a wildcat chamber and then sizing with custom dies, different animal altogether. I'm not an engineer, I'm in no way qualified to assess the " damage" done to the original brass in terms of potential life (of the brass) or safety- but I DO know, it's there, and it's not insignificant.
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Old February 18, 2018, 06:38 PM   #49
Yosemite Steve
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I cut open one of the Nosler cases that had the shoulder pushed back when I shaved .010" off the shell holder and performed a full size. This is a round that was fired and the case head to shoulder became .013" longer from the firing. I can see no weak areas or stretching that occurred in one place such as what happens during case head separation.





My intended case head to shoulder datum length will be .017" longer than the brass that I would like to salvage. It is a large space but if the bullet is seated on the lands the case will remain against the bolt face and the shoulder should be what is reformed. I do wonder about the neck however. The case length is 2.480" With this particular fire forming if it does what I think it will do the neck will be shorter because it will become part of the shoulder. The length of the previous case that was fired became 2.490" because the case stretched and the shoulder did not change it's form or did so very little.
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Old February 18, 2018, 06:44 PM   #50
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tobnpr: no where does Steve say he trimmed a TON of brass from the cases.

You need to start from post #1 and reread the entire thread to see what the original problem is.

As he has proven in his excellent photos, there is no evidence of case head separation.
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