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Old August 14, 2013, 08:26 PM   #1
Okcafe86
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Headspace

I wanted to ask the question as to not get myself into trouble down the road. If you are reloading rifle rounds and you want them full length resized to saami standards, is it nessesary to check headspace?
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Old August 14, 2013, 09:45 PM   #2
big al hunter
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Full length resizing returns the brass to saami standard cartridge dimensions. (Same as factory) Checking headspace is a safety check for the rifle, not the cartridge. Excessive headspace can lead to bad things happening. Usually you won't have to worry about headspace when reloading.

If you notice rings starting to appear near the head of the case that go all the way around, it could be the case thinning out and stretching because of excessive head space.

If you have reason to believe you have a headspace problem a gun smith can check it easily with gauges. Other than that don't worry about it until you are trying to squeeze a little more accuracy out of your loads.
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Old August 14, 2013, 09:46 PM   #3
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Depends on how long you want your brass to last.

Take .308 Winchester as an example. SAAMI chamber headspace is 1.630" min to 1.640" max. SAAMI cartridge headspace is 1.634" - 0.007".

My first question is how do you intend to measure the headspace on the cartridge so that you are on the 0.400" diameter datum reference?

After you determine that, what are you going to set your sizing die for?

I feel much more confident setting the shoulder back 0.002" WHEN the bolt starts to get hard to close. I don't have to be on the exact SAAMI datum point, just on a representative place on the shoulder consistently.

But if you can measure on the SAAMI datum accurately, and size to 1.627", your brass should always chamber but could have very short life. If your rifle is at the max, that means the shoulder is experiencing 0.013" growth each firing. Head separation will occur quickly at that level.
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Old August 14, 2013, 10:30 PM   #4
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As noted, headspace refers to a dimension in the rifle.

However, if you are talking about checking the cartridge's "headspace clearance" (various terms are used for this, including "cartridge headspace" and sometimes simply "headspace"), then that involves a different measurement.

Chamber headspace gauges can't be used to measure cartridge headspace.

The simplest tool is something like a Wilson type gauge -

http://ads.midwayusa.com/product/550...358-winchester

Note that the description refers to the dimension as "cone to head".

As jepp2 noted, you need to set up your resizing die correctly, or you can create a condition known as "induced excess headspace". This has the same consequences as a rifle with a chamber with excess headspace...case head separation. (Which can be very hazardous to the rifle and you.)
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Old August 15, 2013, 05:25 AM   #5
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Yes, it is necessary to check your resized cases for the correct head to shoulder distance, often called case headspace.

Standard full length sizing dies usually set the fired bottleneck case shoulder back way too far when the die's set in the press such that the shell holder stops against it (as most die set instructions state) when the case is full into the die. Depending on the die and shellholder used, a sized bottleneck case may well be smaller than SAAMI specs; you won't know unless you can accurately measure it to a 1/1000th inch accuracy. Your rifle's chamber may be at the long extreme of chamber headspace. Sizing fired cases back to SAAMI minimum (or more with some dies) ends up with excessive head clearance (space between case head and breech face when the round's fired) and case life will be very short and accuracy will suffer.

Using a case gauge, such as the RCBS Precision Mic or Hornady Lock-N-Load (case) Headspace Gauge, one can measure their sized cases then compare them to a fired one to see the difference. Normally, best accuracy and case life happens when the fired case shoulder gets set back 1 to 2 thousandths of an inch.

The Wilson case gauge cannot accurately measure that small of a tolerance as it depends on the eyes of the human to resolve that tiny measurement. Besides, all the Wilson gauge does is compare a case to SAAMI specs (as Wilson makes their gauges to) and does nothing to ensure the case is full length sized best for your rifle and best accuracy and long case life.
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Old August 15, 2013, 06:59 AM   #6
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Quote:
Originally Posted by Bart B.
The Wilson case gauge cannot accurately measure that small of a tolerance as it depends on the eyes of the human to resolve that tiny measurement.
Sure, it can be used this way. However, it is fairly easy to use the depth rod on calipers to measure the offset of the case head.

The first picture shows a case even with the bottom step. But is it? The bottom step for this caliber is 0.006" lower than the top step.



The second picture shows the calipers positioned to measure depth. Note that the machined surfaces "straddle" the gauge upper step to prevent rocking.



The third picture shows the reading. Close to 0.006", so this is at the bottom step.



As the Wilson gauge is oversized in mid-diameters to permit reading fired cases, this technique can be used to measure before and after resizing. It can be used to set up a 0.002" bump, if your caliper hasn't been abused at the depth rod end. ( )

I have the RCBS Precision Mic, too. It gives me the same results, but I find reading the barrel markings isn't always as easy as reading calipers.
Attached Images
File Type: jpg Case gauge 1s.jpg (204.2 KB, 203 views)
File Type: jpg Case gauge 2s.jpg (190.2 KB, 202 views)
File Type: jpg Case gauge 3s.jpg (220.9 KB, 201 views)
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Old August 15, 2013, 09:12 AM   #7
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Bart B. clamed”

“The Wilson case gauge cannot accurately measure that small of a tolerance as it depends on the eyes of the human to resolve that tiny measurement. Besides, all the Wilson gauge does is compare a case to SAAMI specs (as Wilson makes their gauges to) and does nothing to ensure the case is full length sized best for your rifle and best accuracy and long case life”
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Dmazur responds with”

”Sure, it can be used this way. However, it is fairly easy to use the depth rod on calipers to measure the offset of the case head.

The first picture shows a case even with the bottom step. But is it? The bottom step for this caliber is 0.006" lower than the top step”

___________________________________________________________________________________________________________________________________

When the instructions are not read and or ignored the instructions become destructions, L.E. Wilson has included instructions for the gage from the beginning, they have suggest a straight edge. They also identified a straight edge as a pocket rule, it is a tiny step from guessing to the feeler gage or a a flat surface.

Fair and objective, I have no ideal what motivates Bart B. to ignore the evidence presented by Dmazur, I can only guess it would require going back and changing gigs of misinformation posted.

I did notice the information presented in this post suggest the case has a length and the head space information was in the chamber.

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Old August 15, 2013, 02:01 PM   #8
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Well here is the instruction from Wilson on their headspace gauge

http://www.lewilson.com/images/CASE_GAGE.pdf
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Old August 15, 2013, 02:16 PM   #9
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Headspace is in the chamber and there's nothing we can. or should, do about it unless it's too horrible to shoot factory ammo once.

Part of handloading is to custom make our cartridges as needed for our firearm and that includes sizing to perfectly fit our own chamber so the actual headspace isn't a valid issue. Making reloads to SAAMI stsndards only matters if we expect to hand our ammo out to other shooters and few of us do that.
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Old August 15, 2013, 06:30 PM   #10
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Trying for clarity here, not an argument...

Quote:
Originally Posted by wncchester
Part of handloading is to custom make our cartridges as needed for our firearm and that includes sizing to perfectly fit our own chamber...
Which is fine for bolt-action rifles, lever guns and most single-shots.

However, there is a school of thought which suggests SAAMI minimum for gas guns, especially the Garand. Chambering without resistance is the goal, and this takes priority over extended brass life. So, "perfectly fit" may mean a -0.004" bump instead of the customary -0.002", if the rifle is a gas-operated semiauto.
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Old August 16, 2013, 05:05 AM   #11
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I like dmazur's comment
Quote:
So, "perfectly fit" may mean a -0.004" bump instead of the customary -0.002", if the rifle is a gas-operated semiauto.
Especially when there may well be .015" or more head clearance (space between bolt face and case head when the round's fired) in a Garand with a MIL SPEC maximum headspace chamber and ammo whose case headsapce is at the minimum length. There's at least a .007" spread in commercial .30-06 case headspace and military cases are the same according to my measurements.

So, full length sizing a normal, max safe load fired case from a Garand setting its shoulder back .004" has shown to be enough to enable easy chambering and extraction as well as decent case life; 4 or 5 reloads per case. Setting the shoulder back any more will reduce case life.

.001" to .002" shoulder setback for full length sized cases used in bolt guns is ideal for case life as well as accuracy. This allows for variances in head clearance for rifles whose bolt face ain't squared up and fired cases from them having slightly out of square case heads that don't square up when full length sized.

CAUTION - Setting a full length sizing die in the press according to its instructions such that the shell holder stops hard against its bottom while the press handle "cams over" may resize a rimless bottleneck case too much. Its shoulder will be set back too far and the sized case headspace (distance from case head to case shoulder reference) may be less than SAAMI specs. Reloading and firing such cases several times may result in case head separation when fired.

If a new rimless bottleneck case was first fired with a reduced load, it may not completely fill the chamberf from bolt face to chamber shoulder (minus .001" or thereabouts a standard factory load would have, for example). That case may be several thousandths inch too short to use as a reference for setting a full length sizing die such to set its shoulder back a thousandth or two. Use normal, full power safe loads to get a fired case for a reference.
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Old August 16, 2013, 08:19 AM   #12
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Quote:
Originally Posted by Okcafe86
I wanted to ask the question as to not get myself into trouble down the road. If you are reloading rifle rounds and you want them full length resized to saami standards, is it nessesary to check headspace?
Couple questions.

Check headspace of what your rifles chamber, or check your sized brass for proper fit?

What type of rifle are you loading for? Semi-auto, pump, bolt action or other?

What measuring devices do you have to check "headspace"?
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Old August 16, 2013, 09:51 AM   #13
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I wanted to ask the question as to not get myself into trouble down the road. If you are reloading rifle rounds and you want them full length resized to saami standards, is it nessesary to check headspace?
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I am a reloader, I am a case former, my presses and dies have threads, means nothing to another reloader but threads make my dies adjustable in my press.

I do not waste a trip to the range, I determine the length of the chamber first, after determining the length of the chamber I form cases to fit the chamber 'because' there is a correlation between the chamber, die, case and gages. To make all of this work there is 'verifying', I am the fan of verifying.

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Old August 17, 2013, 12:14 PM   #14
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“If you are reloading rifle rounds and you want them full length resized to SAAMI standards, is it necessary to check headspace?”

OKCafe86, when reloaders check head space?? (length of the chamber from the shoulder/datum to the bolt face) they are lead to believe they have three options, go-gage, no go-gage and beyond ‘field reject length’.

When sizing a case a reloader uses a full length sizer die, there is nothing about F.L. sizer that suggest the die is for full length sizing only, My full length sizer dies are versatile sizer dies. I can size cases for short chambers, that would be .012” shorter than full length size, I can size cases from minimum length to beyond field reject length in thousandths. That would be 28 different lengths from short chamber to long chamber with one die and one shell holder. To accomplish this I must know the length of the chamber.

Instead of sizing the cases first to minimum length/full length size first measure the length of the case from the shoulder to the head of the case. After measuring the case length start sizing the case by adjusting the die off the shell holder, I do not recommend the fractional turn measured in degree converted to thousands based on one turn = .071+”, I suggest suing the companion tool to the press, the feeler gage to make adjustments. A good number would be .006” off the shell holder, after sizing a few cases measure the length of the case and attempt chambering the cases. when felt resistance to closing the bolt is experienced, reduce the gap between the die and shell holder.

A reoccurring phrase on a reloading forum: “I bump my shoulder back .002” “, And at one time I ask “How do you do that?” No answer.

.002” from where? No answer.

Back to your question: If you knew the length of the chamber and the length of the chamber was go-gage length you could adjust the die off the shell holder .002” with a feeler gage with a thickness of .002”. If the case chambered with felt resistance you could reduce the gap. I do not know what press you are using, I do not know the case’s ability to resist sizing, when determining the length of the chamber I do not use use cases that have been fired multiply times.

For those that use the “I bump my shoulder back .002” “ method there is a technique that would allow them to verify their adjustment, after bumping? the shoulder back .002: measure the gap between the die and shell holder, nothing like verifying the adjustment.

Problem with bumping, when the shoulder of the die contacts the shoulder of the case the case body is also in contact with the die, and, the neck is contacting the die, for me bumping the shoulder is selective, My versatile dies are not selective, sizing is all or nothing, by the time the shoulder of the die contacts the shoulder of the case the case body and neck are contacting the die also.

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Old August 18, 2013, 10:41 AM   #15
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My simple answer to the OP's question, assuming he's referring to checking headspace of the resized brass, is "no".

More reloaders do not use a gauge like the LNL than do (although I find that foolish).

Factory dies are manufactured so that they cannot "oversize" brass to any significance. In fact, I've found I usually have to set the press to cam over really hard just to get the shoulder bump required.

There would be one heck of a liability "possibility" hanging out there if factory dies were capable of excessive bump. Setting the dies per the manufacturer's recommendation should always be "safe"- though it will most likely not be optimal for brass life.
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Old August 18, 2013, 11:13 AM   #16
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Re: Headspace

I have a set of Lee dies that push the shoulder back too far...so I wouldn't say it never happens.
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Old August 18, 2013, 11:21 AM   #17
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Quote:
Originally Posted by tobnpr
Factory dies are manufactured so that they cannot "oversize" brass to any significance. In fact, I've found I usually have to set the press to cam over really hard just to get the shoulder bump required.
^^^This^^^

They even make Small Base die to bump the shoulder even more without "Oversizing" to the point of "Danger".

Quote:
Originally Posted by Ridgerunner665
I have a set of Lee dies that push the shoulder back too far..
How far is "to far"?
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Old August 18, 2013, 11:30 AM   #18
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Re: Headspace

Far enough that the case is loose enough in the chamber to cause light primer strikes...I'll explain it in detail later, don't have time right now.
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Old August 18, 2013, 05:57 PM   #19
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Setting a fired rimless bottleneck case shoulder to far is when the shoulder's distance from its head is shorter than SAAMI minimum spec. That spec is what the industry and SAAMI feel is safe in a maximum SAAMI spec chamber for it.

For example, a new, never fired minimum .30-06 case with 2.0456" head to shoulder reference will safely fire in a chamber with 2.0587" chamber headspace. That case will have a 0.0131" head clearance when it's chambered and fired. The back part of the case will stretch back until the head's against the bolt face, then the case shrinks a bit as pressure drops.

Note that if that case is full length sized and its shoulder is set back returning it to its original head to shoulder (case headspace, as many call it), then fired, that'll happen all over again. And this will stretch the back end of the case all over again. Subsequent sizing and firing this case will soon stretch the back end of the case such that it weakens enough about 1/4" in front of the head to start cracking; maybe even blowing off in extreme instances.

Therefore, my "safety limit" for setting a rimless bottleneck case shoulder back when full length sizing it is no more than 1/3rd the difference between a SAAMI spec minimum case and maximum chamber headspace. This helps minimize the head separation issue as very little work hardening of the case at this critical point happens. Case life will usually be good. One can see those specs for many cartridges in:

http://www.saami.org/PubResources/CC...0-%20Rifle.pdf

Use any one of several gauges on the market to measure your fired case headspace and compare that to what a sized case headspace is. It's best to take the average of 5 fired cases then compare their average to the average of 5 resized ones.

My "accuracy limit" is setting the shoulder back no more than .003". A maximum of .002" will give the most case life as well as best accuracy as many folks have proved over the years of experience.
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Old August 18, 2013, 06:23 PM   #20
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Re: Headspace

Bart may remember us discussing this once before...

I was having trouble with light primer strikes in my 30-06...I checked everything...firing pin protrusion, headspace, replaced striker spring, bought new primers...nothing helped, I was still getting random FTF's due to light strikes...

I took it to a gunsmith along with some fired brass...he checked everything...found nothing wrong...the headspace is within spec and on the tight side of that...the firing pin protrusion was a little less than perfect, but was within spec (.056)

He asked me to bring in my dies...he sized a case and checked it...it pushed the shoulder back too far (2.0432"...IIRC) bought a set of Redding Master Hunter dies and the old girl has went bang every time since.

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Old August 18, 2013, 06:46 PM   #21
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I use my sinclair bullet comparator that attaches to my calipers for checking how much I need to bump my case shoulder. That gives me something similar to the datum line reference on my fired cases. I also record this dimension in my notes and I can see if I have a developing problem. As has been said, adjust the dies so you only bump the shoulder .002 to .004. Cartridges chamber easy and case life is extended.
The case does need to be deprimed for this measurement. I did make my own attachment for the other caliper jaw that indexes on the primer hole to center the case, but the measurement is taken off the face. This makes the case a lot easier to hold in the calipers and it keeps it located in the same place.
I do use a straight edge to check for flat faces on the case. Not each one about every 10 or so until I find a bad one.
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Old August 18, 2013, 10:15 PM   #22
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Lucas, have you ever measured case heads being out of square with their body-neck axis?

Or for bolt faces being out of square with the bore-chamber axis?
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Old August 18, 2013, 11:35 PM   #23
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Bart B
I have played around with a dial indicator the bullet concentricity device,That all.
As far as the face being square that was done when action was squared and trued up.
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Old August 19, 2013, 05:14 PM   #24
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Lucas, as long as the bolt face was squared up with the barrel tenon thread axis and not the bolt axis, you're good to go.
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Old August 20, 2013, 07:37 AM   #25
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“He asked me to bring in my dies...he sized a case and checked it...it pushed the shoulder back too far (2.0432"...IIRC) bought a set of Redding Master Hunter dies and the old girl has went bang every time since”

Ridgerunner665,

http://www.saami.org/PubResources/CC...pringfield.pdf

The minimum length/full length sized case distance from the shoulder/datum to the case head is 2.052, then there is verifying, I am the fan of verifying, I could be ‘THE VERIFIER”. There was a time on the Internet the rage was to grind the bottom of the die and or top of the shell holders, grinding the bottom of the die .020” will allow a reloader to form cases for short chambers. it should not be a problem but reloaders should be able to keep up with the math,

To use your short die all you would have had to do was adjust the die off the shell holder .020”, then after making the adjustment it would have been necessary to secure the die to the press with the lock ring.

Then? It should have been asked “What rifle?” Control feed or push feed? I have fired 8mm57 ammo in an 8mm06 chamber, HEAD SPACE!!! You talk about head space, the chamber length differenced in length between the 8mm06 and 8mm57 is .127”, You experienced light primer strikes with .020”, I exceeded the firing pin protrusion, and still, my cases did not stretch and they always fire.

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