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Old November 10, 2012, 02:29 PM   #1
SEHunter
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To determine the headspace for a specific gun (and the sized cases for that same gun), does my headspace measurement come from measuring the head space of a once fired case in that gun or do i measure the chamber with a tool and then use that measurement to set my die?

What guages/tools do i need to purchase to be able to measure head space? There are so many products and i get them confused as to which one i need and what they do.

My main goal right now is to determine head space and correctly adjust my dies. I use RCBS standard dies-are these good enough to perform good sizing? Please use laymans terms

Forgot to add- im FL sizing

Am looking at the Redding FL bushing die. What size bushing do i need for the 22-250?

Last edited by Unclenick; November 11, 2012 at 11:18 PM. Reason: Merged consecutive posts
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Old November 10, 2012, 03:01 PM   #2
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Measuring headspace and resizing a fired case are two different things. When your firearm was built, the chamber headspace was checked to verify it was within SAAMI specification. "GO" and "NO GO" gauges were used. Unless you are building a firearm, or checking the condition of a old or extensively used suspect firearm, there's no practical reason for you to own "GO" and "NO GO" gauges.

When resizing fired cases with a full length sizing die, you simply follow the die makers instructions to set the dies up... doing this will insure that the case is re-sized to within SAAMI specification. It may end up being a bit dimensionally smaller than absolutely necessary, but it will be in spec, and it will ensure proper function in your firearm.
As you gain knowledge, and learn more about the what and why of reloading, you can start to make adjustments as you see fit.

I can go on and on here about datum lines and shoulder bumps... but the above is sufficient to answer your question in the "layman's terms" you requested.
Quote:
Am looking at the Redding FL bushing die. What size bushing do i need for the 22-250?
If you don't know what a bushing die is for, you many be in over your head. In simple terms, a bushing die allows you to adjust the amount of neck tension on the bullet... a variable that can effect function and accuracy. No one can tell you what size because no one knows what brass you're using, the case/neck wall thickness, the actual bullet diameter or the chamber neck diameter. If you don't know these things, again, you may want to stay away from bushing dies until you understand the variables.

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Old November 10, 2012, 03:28 PM   #3
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Thanks for the info. I appreciate the laymans terms. Alot of folks here are far beyond my understanding when it comes to the wording.

I measured the mouth's OD of a fired Win. case from my gun and its .255 to .256 so i am ordering a .248 and .249 bushings. This seems to be consistant with my research so far.

I have loaded for 8 or 9 years and am pretty particular on consistancy with case prepping and powder charging but i have always used standard dies and have adjusted them as directed in the instructions. I want to take it to another level so that is why i want to begin to size based off what head space my chamber needs instead of always pushing the shouler too far back like i know i am doing. I also am looking to move to a Redding bushing die so that i can eliminate the expander ball.

I have been advised to pick up the RCBS measuring kit to measure my fired cases so thats what i am about to do. I mainly am in need of the tips that come along with properly measuring a fired case and correctly adjusting my die so that i am getting the minus .001 or.002 measurement to the case shoulder.
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Old November 10, 2012, 03:35 PM   #4
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For setting up my dies I prefer case gauges such as those sold by Dillon or L.E. Wilson.
I just drop a sized case in the case gauge and I can visually see if the shoulder is pushed back enough or too far.
It will also tell me if it is time to trim the case.

I have other case measuring tools depending on what I am trying to accomplish but for setting up dies the case gauge is simple and foolproof.
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Old November 10, 2012, 03:41 PM   #5
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Whats your reference point when using that tool? does it just tell you what sammi spec is or can it be used to custom size the case to your rifles head space?
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Old November 10, 2012, 03:58 PM   #6
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If the base of the case is flush with the gauge you are at maximum SAAMI headspace. There is a notch cut into the gauge so that you can see minimum SAAMI headspace.
If the head is sitting proud of the gauge the die needs to be brought down a bit. If the head sits below the minimum headspace notch the die needs to be brought up some.
On the other end which is shown in the picture you can see the maximum case length and the notch for minimum case length.
I generally use this for my semi-auto rifles. If it fits in the case gauge it fits in the chamber.


For my precision rifle I use a headspace gauge to measure a fired case and set my full length die 0.001" shorter.
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Old November 10, 2012, 08:27 PM   #7
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I see. That would help me for loading for my Marlin 336.

What is the most commonly used FL bushing die? i am looking at the Redding S type.
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Old November 10, 2012, 08:57 PM   #8
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You are asking about a bump gauge, sometimes called a "headspace gauge" incorrectly. Hornady and Sinclair both make very similar tools. For a bolt action rifle, the idea is to move the shoulder back .001-.003" from the point where you can just barely close the action on a case. For semiautos, the goal is about .003-.005". However, it's harder to find the point where a case just barely chambers. Disassembling the bolt probably is necessary, depending on the rifle.

If you are after more accuracy, then Hornady's OAL gauge is extremely helpful for finding the optimal overall length for a specific bullet in your particular rifle. IMHO finding the best OAL is an early step in making more accurate handloads.

The bushing resizing die is out of my league. At that point you need to pay attention to neck wall thickness, bullet diameter, concentricity etc. All important to maximize long-range accuracy. I simply don't shoot at that level.
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Old November 10, 2012, 08:59 PM   #9
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That makes two of us but i am about to try.
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Old November 11, 2012, 11:55 AM   #10
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SEHunter, consider the following......

Bushing dies are easy to use. Before you get one, measure the neck diameter of some loaded rounds and find the average. If your case necks average .251", get a bushing that's .249" and that'll do for 97% of your ammo.

Also, get an RCBS Precision Mic to measure case headspace; the distance from the case head to the case shoulder's reference point. Then adjust your full length sizing die to set fired case shoulder back .002".

Chamber headspace is measured from the bolt face to the reference point in the chamber shoulder. For the .22-.250, it's typically between 1.575" and 1.585". Fired cases from your chamber will be 1 to 2 thousandths shorter in case headspace than what chamber headspace is. New cases have case headspace between 1.571" and 1.578".
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Old November 11, 2012, 02:24 PM   #11
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Just wondering- since a fired case is roughly .001 to .002 shorter than the chamber, is it not advised to FL size and push the shoulder back to the original length of a fired case? Basically, just using the head space measurement from a fired case as my die adjustment measurement. Theoretically, it should still chamber easily since that measurement is less than the chamber, right?
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Old November 11, 2012, 03:02 PM   #12
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SEHunter, full length sizing cases and setting their shoulder back a bit ends up with a small spread in their head-to-shoulder dimension. If you try to set the die such that sized case headspace is the same as fired case headspace, some of the sized cases will be a bit longer. Those may start binding the bolt a bit when they're chambered. It all depends on how much lube's put on the case, what the lube's slipperyness is and how springy your reloading press is.

Sized cases with 2 to 3 thousandths clearance from bolt fact to shoulder's not a problem. If it's over 4 thousandths, then cases stretch too much and case head separation may start to happen after a few full length sizings of the same case.
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Old November 11, 2012, 06:41 PM   #13
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cartridge case gauges aren't infallible

One would think the Wilson cartridge case gauge or Dillon would be accurate from minimum to max length, tain't so!! I have several L.E.Wilson gages that are spot on, the exception is my 280Rem which is .006" short. I've had several 280Rem rifles in my life, currently have two, Winchester model 70 Classic and a Ruger model 77 Hawkeye. The Ruger is the most current, I discovered fired cases from the RUGERS CHAMBER were flush with top step indicating max head space. I had built a 280Rem for my son and still have both the go and no go headspace gauges, I inserted the go gauge in my Ruger's chamber and the bolt closed as it should, I checked the No Go gauge and the bolt would not close?? I decided it was time to check the Wilson cartridge case gage, my chamber go gauge was flush with the top step, the Wilson cartridge case gage had been cut .006" short. I felt a little foolish when I discovered I had made one to many assumptions. Just remember the gages are just a tool, no better than the man who cut and in my case failed to verify the length of the Wilson cartridge case gage before it left the factory. William
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Old November 11, 2012, 07:18 PM   #14
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got it, thanks.
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Old November 11, 2012, 11:24 PM   #15
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The use of case gauges will indicate whether your resized cases are within SAAMI tolerances but can result in oversizing cases for your particular chamber. There are several tools available for measuring fired brass and can be used to set up your dies to your particular rifle. The Hornady, RCBS Precision Mic and Innovative Technologies tools all work well. For my bolt guns, I prefer the IT gauge since it is very accurate but does not work well for gas guns. The RCBS tool work better in that situation. I typically neck size but on occasion have to bump the shoulders with a body die. I set the die to set the shoulder back .0015 to .002. This allows easy chambering and doesn't overwork the brass. The process of setting up FL is the same as with body dies.

One way to determine bushing size is to measure the neck wall thickness multiply by two then add the diameter of the bullet. Then subtract the desired neck tension. Example for 22-250: brass has a neck thickness of .014 x 2 = .028 + .224 =.252 - .002 (desired neck tension) = .250 bushing.
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Old November 12, 2012, 12:13 AM   #16
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SE,

How much spring back in length you'll get actually depends on the pressures you are loading to and the condition of the chamber. It can also be affected by how well your bolt and receiver lugs mate. Keep in mind that what stretches longitudinally in a case the most is the short length of brass that forms the pressure ring, which is not long enough to have as much spring back as you might think.

If you want a more accurate measurement from a case, you'll need to neck size and re-fire the same case several times, measuring it each time to see what limit it's heading toward, or continuing to shoot it and measure it and stopping when you start to feel light resistance when chambering, then using the previous measurement. But just bumping the shoulder back from as-fired size by 0.001" to 0.002", as Bart described, is a method that has been used by a lot of people for a long time with good success.
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Old November 12, 2012, 10:11 AM   #17
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jdillion, thanks- .250 just happens to be exactly what i came up with after measuring as you described as well as measuring a loaded case and than subtracting .002

Unclenick, thanks for the explanation. This particular gun is new with maybe 50 rounds shot. The only fired cases i have are once fired factory rounds. I think they would serve as a good starting point to take a measurement from. I do tend to load my handloads on the warm side so once i have a few fired from my handloads, i will take measurements again to see how they react as far as stretching.

As far as consistant sizing goes, if i size a case and still want to push the shoulder back more, am i better off to size an un-sized case after i make the die adjustment or will it work fine to use the same case that i just sized?
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Old November 12, 2012, 10:48 AM   #18
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SEHunter, Before you settle on a bushing size you should buy a good ball mike as neck thickness will vary. Just don't measure one spot do it in various spots around neck.
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Old November 12, 2012, 01:27 PM   #19
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“I have other case measuring tools depending on what I am trying to accomplish but for setting up dies the case gauge is simple and foolproof”

No such thing as foolproof, fools do not read, listen, consider other remedies, methods and or technique. The Wislon case gage is not a drop-in gage, from the big inning L.E. Wilson understood the concept of ‘DATUMS’ when a case is inserted into a Wilson case gage it does not set on the shoulder in the gage, it sits on a datum with a radius, back to “for setting up dies the case gauge is simple and foolproof”, if it was foolproof the owner and user of the case gage would know and understand how to adjust the die from the measurement as in from the datum to the top the head of the case when adjusting the FL die. Most owners of the Wilson case gage use their thumb nail, me? I am not that good, I use a straight edge, Wilson suggest using the pocket rule??? as a straight edge like a pocket rule is included in a list of tools found on the bench or pocket of a reloader, and then there is the thickness gage/feeler gage as in laying the straight edge across the top of the case and or gage to measure opens as in open pointers?

Length of the chamber, again, this stuff does not run me into a curb, the practice of firing a case to forum is not necessary, becoming familiar with the tools and their function is not necessary as demonstrated by some of the answers/responses. After firing I eject once fired cases, the accepted practice in reloading is to fire to form , then it goes round and round, full length size? Neck size? A reloader that is familiar with the press, the die, the shell holder and has a good understanding of thread/incline plane can form cases to fit before firing, back to my favorite cases, first, the 280 Remington, there is no way I can fail to size a case for the 30/06 family of chambers, again, the 280 Remington case is longer from the head of the case to the shoulder/datums by .051” as in chambering a 280 Remington case in a 30/06 chamber, the protruding case head of the 280 Remington case will cause the bolt to protrude from the rear of the receiver by .051” less the difference in length between a go-gage chamber and a minimum length sized/ new, factor loaded round ‘in the perfect world’.


“I have other case measuring tools depending on what I am trying to accomplish.....” again, this stuff does not drive me to the curb, or lock me up, back to the 280 Remington case in the 30/06 chamber, if a reloader has a good understanding of tools and their use and can measure the length of the 280 Remington case from the head of the case to its shoulder, the same reloader that can use the 280 Remington case length from the usual places can use the case to measure the length of the chamber in thousandths, my problem when teaching that concept is getting someone to understand the concept of .000” (ZERO).

Back to the smith in Utah, he used one gage to measure the length of the chamber from the face of the bolt to the shoulder/datums of the chamber. Reloaders and smiths have blamed him for all the M1917 chambers that are long from the bolt face to the shoulder of the chamber. OGEK, they never ask him “HOW DO YOU DO THAT?” Instead they mindlessly attempted chambering a field reject gage, if the field reject gage would not allow the bolt to close the attempted the no go-gage, if the no go-gage would not allow the bolt to close they went for the go-gage, and I ask “WHO DID NOT KNOW THE BOLT WOULD CLOSE ON THE GO-GAGE? With all that effort, not one of the smiths could indicate the length of the chamber in thousandths.

I have a Eddystone M1917 with a long chamber, not a problem, I form/size 280 Remington cases by erasing the shoulder of the 280 Remington case and reforming it .037” back, or .014” ahead of the 30/06 shoulder. I am the fan of cutting down on all that case travel and, NO! my case heads do not separate, my cases, when fired can not run to the front of the chamber when avoiding the primer strike, my firing pins are mechanically driven with a spring.

F. Guffey

Last edited by F. Guffey; November 12, 2012 at 01:28 PM. Reason: change o to an i
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Old November 12, 2012, 02:21 PM   #20
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Headspace for .50 BMG

OK guys, then I have a question concerning headspace. I am reloading for a .50BMG and recently purchased a Lyman headspace gauge. Some of my cases are spot on between the minimum and maximum on the gauge but some of my cases are up to .010 shorter than the minimum on the gauge. When loading for a caliber this large I would think this is a large problem but in doing research some say that this measurement is within acceptable ranges, but is that a measurement that will lead to case head separation upon firing in my bolt gun? I have not shot any cases yet and have only reloaded the cases that were completely spot on. AND some of the cases that are short on headspace dimentions are all spot on for OAL after trimming. Any help on this?
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Old November 12, 2012, 03:31 PM   #21
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“OK guys, then I have a question concerning headspace. I am reloading for a .50BMG and recently purchased a Lyman headspace gauge. Some of my cases are spot on between the minimum”

http://www.midwayusa.com/product/983...ce-gage-50-bmg

You have purchased a case gage, back to that part where reloaders refer to a comparator as a head space gage. In the bottom of the case gage is a datum, a datum is not something most reloaders have learned to appreciate. I do not know which 50 BMG you have, I do not know if it is a single shot or if it loads from a magazine. I load for the chamber, I know the length of the chamber from the bolt face to the shoulder of the chamber first.

On the outside chance you do have a head space gage you could use the head space gage to check the accuracy of your case gage BUT! you would still be without a clue if you do not have the means to measure the length of the chamber from the bolt face to the shoulder of the chamber. There are 50 BMBs that are built that are all forgiving when firing for the first time, after firing the first time in chambers that are forgiving when the case is formed I apply the leaver policy, once the shoulder is out there, I “leaver” out there.

Again, we all know the head space gage will allow the bolt to close.

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Old November 12, 2012, 04:15 PM   #22
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Mr. Guffey, Yes I purchased the gauge you spoke of to assist me in reloading. I have a box fed bolt action .50 so here is a silly question...how do you measure for the length of the chamber for a particular(mine) firearm? I have taken this gauge and measured some already loaded factory rounds and some of them even have a gap of .010 from the minimum on the gauge to the case head of the round. If my gap is such, on as yet non loaded cases, will it hurt the gun(and possibly myself) to shoot them or do I need to discard these cases and only load those that meet the criteria in this gauge? Also some rounds were fire formed in my rifle and some were purchased cases and are as yet unfired in my rifle. Thanks.
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Old November 13, 2012, 09:07 AM   #23
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The following's a link to a gauge that measures case headspace for the 50 BMG round.

http://www.giraudtool.com/50bmgcomp.htm

It measures the distance from the case head to the reference point on the case. If you're measuring a fired case that had a normal, safe maximum load in it, you can add 2 thousandths to the reading and that's typically going to be within 1 thousandths of what your rifle's chamber headspace is. Otherwise, to get your rifle's exact headspace dimension, you'll need an adjustable 50 BMG headspace gauge and follow its directions to measure the chamber headspace.

Then use this Giraud Tool gauge to measure your resized fired cases and set the sizing die in the press to make sized cases about 3 to 4 thousandths shorter than what fired ones have.

I've searched the internet on earth as well as Mars and Jupiter and no specific 50 BMG chamber headspace dimension specs could be found. Lots of gauges out there, but nothing as to specs in the traditional manner of measuring them.
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Old November 25, 2012, 12:59 PM   #24
F. Guffey
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JRLSH, “to get your rifle's exact headspace dimension, you'll need an adjustable 50 BMG headspace gauge and follow its directions to measure the chamber headspace”
AND THEN

I've searched the internet on earth as well as Mars and Jupiter and no specific 50 BMG chamber headspace dimension specs could be found. Lots of gauges out there, but nothing as to specs in the traditional manner of measuring them.



“to get your rifle's exact headspace dimension......etc., etc..” Next? Bench resters, bench resters for years have done it this way and or that way? And me? I say fantastic, just fantastic.

JRLSH, In the big inning there was a gage, something like a thickness gage (OR? the companion tool to the press, the feeler gage) one end was stamped ‘go’ the other ‘no-go’. The difference in thickness between the two was ‘IT’. With the ‘go’ on one end and ‘no-go’ on the other was a chain that attached a timing gage in two pieces.

‘IT’ was described as:

Headspace is the distance between the face of the bolt and base of the cartridge case, fully seated in the chamber. Head space adjustment is correct when the when the following conditions are met:

1. etc..

2, etc..

Again, nothing drives me to the curb, nothing lock me up, the 50 BMG is one of the easiest chambers to measure for length from the bolt face to the shoulder of the chamber, back to ‘I said’, “I can measure the length of any chamber without a head space gage, I am not determining head space, I am determining the length of the chamber (again) from the bolt face to the shoulder of the chamber”, how is that possible? ‘PREDETERMINED’ the word predetermined, to most, has a magical significants or grants insight to the user of the word. Predetermined. the word, is used in glossy of terms, you ask ‘How to check ‘it’?” the answers you get are getting appear to be answers to “What is head space”, not answers as to “How to check head space”.

I believe it is safe to say I have 200+ 50 BMG cases, I have access to 1,000s more, fired and new, again I said the light does not go out when the bolt closes meaning the chamber does not get dark because it seems there is no way light can get, the light?.

Many years ago Springfield claimed they never say a 98 Mauser, the 98 came with a third safety lug, the Springfield 03 came with a third safety lug, the Mauser 3rd lug was hidden, the 03 Springfield lug was exposed on the right side when the bolt was closed. I thought the design was brilliant, Springfield could have measured the gap between the rear 3 lug and front of the rear receiver ring, THEN! made a permanent record of the position of the bolt in reference to bolt seating surface, they could have had a a running record of bolt set back, they were not brilliant and they never noticed the potential. Had they noticed the exposed lug ahead of the rear receiver ring they could have determined the difference in length between the length of the case and the length of the case/ammo from the usual places being fired, they ALSO could have determined head space as in the length of the chamber from the bolt face to the shoulder of the chamber if they had been brilliant, the were not....brilliant. they could have chambered a head space gage as in go-gage length then measured the forward movement of the bolt until the case shoulder hit the chamber shoulder, back to the gap, the difference in the gap with the lugs seated and the bolt pushed forward with a go gage would have determined the difference in length between the case length and chamber length in thousandths, then came Hatcher, to Hatcher it was a ‘sticky-out’ thing in front of the rear receiver ring. To collectors the protruding lug is a way to determine period correctness, and of course JIC, as just in case something going wrong with the other two lugs. Collectors have noticed the gap is not as wide as the gap on later models.

JRLSH, I can make a gage, again, the 50 BMG is not difficult, the one thing I can not do is use a reloading forum, I need your email address, a phone number would help.

F. Guffey
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Old November 25, 2012, 02:14 PM   #25
Bart B.
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For over a century, "headspace" has been what SAAMI's glossary says:

Quote:
HEADSPACE
The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.


HEADSPACE GAGE
A device used in a firearm to determine the distance between the breech face and the chamber surface on which the cartridge seats. Also called Breeching Plug.
For rimless cases, it is the distance from the breech face (bolt face in a bolt action rifle) to the chamber point where the case mouth stops against when the firing pin falls.

For rimless bottleneck cases, it is the distance from the breech face (bolt face in a bolt action rifle) to the chamber shoulder reference point where the case shoulder stops against when the firing pin falls.

For belted cases, it is the distance from the breech face (bolt face in a bolt action rifle) to the chamber point where the case belt stops against when the firing pin falls.

For rimmed cases, both straight or bottleneck, it is the distance from the breech face (bolt face in a bolt action rifle) to the chamber point where the case rim stops against when the firing pin falls.

A GO gauge is marked with the dimension that's minimim for SAAMI standards. The NO-GO gauge is marked with the dimension that's SAAMI spec maximum.

Headspace has never officially meant to be the space between the breech face and the case head of a round full forward in the chamber, but it's far too often misused this way. It's correctely called head clearance as stated in SAAMI's glossary:
Quote:
HEAD CLEARANCE
The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.
Headspace for many rifle cartridges can be seen at

http://www.saami.org/specifications_...wnload/206.pdf

Last edited by Bart B.; November 25, 2012 at 02:33 PM.
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