How should I determine headspace.

Bytesniffer · December 19, 2016, 09:02 PM

I was thinking
Take a trimmed sized
Case 7.62 2.008
Neck lightly crimped
Put bullet in case
And chamber , slowly
Until bullet is pushed on to
Lands and into case.
After removing round
then back off
A few thousand's.
Any reason why this
Wouldn't work ?

firewrench044 · December 19, 2016, 11:10 PM

You may need to remove the ejector from
the bolt to get an accurate size

Many have done it that way before

5whiskey · December 19, 2016, 11:22 PM

OK you're not talking about headspace there, you're referring to seating depth in reference to the rifling. I would start by seating long, then gradually seat deeper. I mark the projectile with a sharpie, and seat gradually deeper until the rifling leaves no smudges or marks on the sharpie colored portion.

Once I find that point, I usually seat at least .02 deeper, and that is quite close. Some rifles like a longer "jump" to the lands. Some like a very short distance, but beware that seating to close to the lands can increase pressure. Hence, why I'm at least .02 off.

RKG · December 19, 2016, 11:55 PM

http://m.hornady.com/store/Lock-N-Lo...traight-1Each/

Reloadron · December 20, 2016, 11:52 AM

Quote:

How should I determine headspace.
I was thinking
Take a trimmed sized
Case 7.62 2.008
Neck lightly crimped
Put bullet in case
And chamber , slowly
Until bullet is pushed on to
Lands and into case.
After removing round
then back off
A few thousand's.
Any reason why this
Wouldn't work ?

As mentioned, you are not describing headspace but rather bullet seating depth or bullet off the lands. There is the:
LOCK-N-LOAD® OAL GAUGE STRAIGHT as one solution and there is also the RCBS Precision Mic as another option.
You can also use your chamber to seat a bullet as you mention but if I use my bolt to seat a bullet in my chamber then for example measure the C.O.A.L. it won't be consistent because it would only work for one bullet type and even within that type bullets vary tip to ogive as well as bullet length.

As to Headspace?

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.

The above from our friends at SAAMI.

Ron

Bytesniffer · December 20, 2016, 11:56 AM

Firewrench044,
Doesn't the chamber
Space determine where the
Center of the shoulder for your
Cartridge stops the bullet
From traveling to far into the
Lands .ie rifling.
The rifle thats in for repair
Is chambered 7.62 and is
Longer then 308.
When my cartridge stops the
Bullet from traveling further
Into lands thats what I want to
Understand.

F. Guffey · December 20, 2016, 12:28 PM

How should I determine headspace.

--------------------------------------------------------------------------------

Quote:

I was thinking
Take a trimmed sized
Case 7.62 2.008
Neck lightly crimped
Put bullet in case
And chamber , slowly
Until bullet is pushed on to
Lands and into case.
After removing round
then back off
A few thousand's.
Any reason why this
Wouldn't work ?

Any reason why this wouldn't work? I can think of one reason; nothing you have described has anything to do with head space. At best if I was guessing I would guess you are trying to determine the distance from the rifling to the bolt face. I believe that would have something to do with seating the bullet to the lands, or off the lands, or into the lands.

F. Guffey

F. Guffey · December 20, 2016, 12:35 PM

I am the fan of shop skills. if you have mastered the .002" bump you should be able to master the .004" bump and the .006" bump and the .008" bump and the .010" pump.

I go beyond the 'bump the shoulder', fact is I find it most difficult but when sizing a case and controlling the length of the case from the shoulder of the case to the case head I sized the cases in thousandths. I form short chamber cases, I form long chamber cases.

And then there are methods a reloader could use when determining the length of the chamber from the shoulder to the bolt face in thousandths.

F. Guffey

F. Guffey · December 20, 2016, 12:39 PM

But; before the bump the reloader must be able to determine the length of the case from the shoulder to the case head. My favorite case is the case that requires .014" bump

to get it to minimum length/full length sized, and I believe it important the reloader knows what a minimum length/full length sized case is.

F. Guffey

**Unclenick** · December 20, 2016, 02:50 PM

Bytesniffer,

A chamber's headspace is a measure of how much room it has for a cartridge case, and excess headspace is the amount of room the chamber has for a cartridge case to rattle back and forth in the chamber. The bullet is not involved at all. I think the fact some people use the word "head" to mean "bullet" has perhaps caused your confusion. The "head" in headspace refers to the pressure head formed by the brass at the breech end of the gun.

RC20 · December 20, 2016, 04:10 PM

Quote:

But; before the bump the reloader must be able to determine the length of the case from the shoulder to the case head. My favorite case is the case that requires .014" bump to get it to minimum length/full length sized, and I believe it important the reloader knows what a minimum length/full length sized case is.

Latin comes to mind.

JeepHammer · December 20, 2016, 09:19 PM

Headspace: From base of case against bolt face to 'Datum Line' on case shoulder.

Picture is worth 1,000 words,
http://i1298.photobucket.com/albums/...ps8j7sg7xk.jpg

Bullet seating depth is what you described.
Seating depth determines how far off the rifling the bullet sets.

Neck length is determined from 'Datum Line' to neck mouth, where the bullets fits into the case.
All a neck does is hold the bullet center with the bore, so neck length under 'Maximum' isn't a big deal.

JeepHammer · December 20, 2016, 09:27 PM

With a properly sized case (Start with SAAMI for point of reference or 'Zero' point) your particular chamber could be +/- SAAMI specification.
Most chambers are not exact.

With a factory case that passes in a headspace gauge,
Simply oil the bolt face,
Insert a factory round in the chamber,
Use 'Plastic-Gauge' on the case head,
Carefully close, then open the bolt.

Plastic-gauge is a plastic fillies that that flattens out at a specific rate, and holds its shape so you can determine compression.
Available for cheap at any auto parts store...

The case headspace, plus what the plasti-gauge tells you will give you a very close reading of the actual headspace length of your chamber for a couple bucks.

JeepHammer · December 20, 2016, 09:33 PM

To be more precise, you will need speciality tools.
A Datum Line adapter on your caliper to be precise.

Use the standard LE Wilson (or comparable) heads space go/nogo gauge to produce a brass sized a little long,
Keep bumping the shoulder back & measuring the brass with caliper/Datum Line adapter until the case fits into the chamber with no effort/extra pressure on the bolt when compared to an empty chamber.

At the point the shoulder is bumped back far enough the bolt closes with no ADDED resistance, you have found your particular headspace length.

BillM · December 20, 2016, 09:42 PM

Quote:

The rifle thats in for repair
Is chambered 7.62 and is
Longer then 308.

What is the rifle, what is the problem, and are YOU the one doing
the repair? For yourself on your own rifle, or are you doing repairs
for someone else? Or is it a rifle that's "in for repair" at a gunsmith
or manufacturer?

Headspace has nothing to do with bullet seating depth, as several
people have mentioned. If the rifle has excess headspace, the only
sure fix (depending on the rifle) is a new barrel, adjust the barrel
(Savage) or "set back" the barrel and re-chamber.

ETA: On the remote chance that this is a Ishapore Enfield in
7.62 x 51---you can adjust headspace by replacing the bolt
head with a longer/shorter one.

firewrench044 · December 21, 2016, 12:01 AM

Bvtesniffer --

In most rifles the ejector is in the bolt
it will put sideways tension on the cartridge
sometimes a little sometimes a lot
that tension can (not always ) cause you to get
a false reading
It is usually easy to remove the ejector
and eliminate that possible problem
( just don't let it fly across the room, put a rag
there and catch it )

Also some extractors do not hold the cartridge
tight against the bolt and the spring tension of the
ejector pushes the cartridge away from the bolt
again giving you a false reading

firewrench044 · December 21, 2016, 05:31 AM

Have sent a message
call me
I will clarify this stuff on the phone

I have tried to post answers twice and it will not go through

T. O'Heir · December 21, 2016, 03:22 PM

Headspace is a rifle manufacturing tolerance that has nothing to do with the cartridge.
The standard LE Wilson (or comparable) headspace go/no-go gauge is not a headspace gauge. Cartridges do not have headspace. The Wilson thingy is a case length gauge.
"...some extractors do not hold the cartridge tight against the bolt..." Isn't what the extractor is for.
"...an Ishapore Enfield..." Really expensive things to fix headspace on. Requires a handful of bolt heads(no numbers on 'em) and proper headspace gauges. Doesn't require a new barrel.

Reloadron · December 21, 2016, 04:12 PM

Something about one picture is worth... comes to mind.

I believe what the original poster had in mind as a case gauge of sorts and was concerned with bullet seating depth or how far to seat off the lands. Regardless, there are likely a dozen case gauge variations out there to be had, LE Wilson and Forrester come to mind, assorted seating gauges Hornady and RCBS off the top and finallt headspace gauges which as mentioned are a chamber gauge and have nothing to do with cartridges or cases.

Ron

**Unclenick** · December 21, 2016, 04:14 PM

Headspace is a chamber characteristic, and a gun still has a headspace value whether it is within any accepted tolerance or not. There is a standard headspace tolerance for each chambering for new guns, but there is also a field reject headspace tolerance limit that is outside the manufacturing tolerance and which armorers and gunsmiths use to decide when a barrel needs to be replaced or set back and rechambered. All this, however, is only necessary for remaining on good terms with commercial cartridge standards. Many a wildcatter has changed the headspace in his chamber to something nobody else in the world uses, but his chamber still has headspace. Anyone with headspace outside the manufacturing tolerances can load fire-formed cases to match it, as if it were a wildcat, and they still have headspace.

The case gauge determines if a case will fit inside a chamber with new-gun minimum tolerance headspace.

An indirect headspace gauge, like the case thimble of the RCBS Precision Mic, is making what is called an indirect or take-off measurement of the headspace of a chamber by examining what size a case fire-forms to inside the chamber. Due to brass spring-back, this is not a precise measurement. Like any indirect measurement made by measuring dimensional mirroring by an intermediary, the error in the intermediary has to be added to the measurement error. In this case the intermediary is the fire-formed case, which is typically a thousandth smaller than the chamber.

firewrench044 · December 21, 2016, 05:22 PM

Bytesniffer --

Head space -- is the distance between the case and chamber

Distance to lands (or jump ) -- is distance between bullet and
rifling (or lands)

I think you are after the Distance to lands ( jump )
I believe your mistake in terminology has many in this thread
answering the wrong question

To use a case and bullet to determine Distance to lands
do not crimp bullet
make 4 cuts in the case neck (so the bullet moves very freely
with minor resistance )
after putting bullet into chamber and closing the bolt gently
remove the bullet and measure the length of the cartridge
from base to the oglive ( you need a special tool )
( oglive is the place on the bullet where it touches the lands )

Hornady makes that tool, RCBS also makes it, it comes in a set
( that is what I use -- RCBS Precision MIC. 308 WIN.
P/N -- 88329 , the set has 3 tools with good instructions
and good illustrations )

Please forgive my spelling, I am a mechanic, I can make your car, light truck, medium truck, semi or firetruck dance ( certified in all ) but spelling is sometimes beyond me

F. Guffey · December 21, 2016, 06:11 PM

Quote:

Unread Today, 04:12 PM #19
Reloadron
Senior Member

Join Date: June 8, 2016
Location: Cleveland, Ohio Suburbs
Posts: 446 Something about one picture is worth... comes to mind.

The picture would have made more sense had you placed the head space gage into the case gage. Again for the 200th time the Wilson case gage is a datum based tool. Somewhere down inside of that gage is a datum, it is not like my datums because my datums have sharp edges. The Wilson case gage has a datum with a radius' I know' everyone is wondering' "How do they do that?". The Wilson case gage has been with us for 65+ years so I am thinking those of us that do not know never will.

Reloadron, if the head space gages are 308W and the case gages are 308 W the head space gage should be flush with the top of the case gage. For those that know their way around the feeler gage it would be easy for the reloader to pace a straight edge across the top of the case gage and measure for gaps. Some reloaders are good at measuring gaps with light. I passed on a light measuring gage, the gage came with the instructions; I thumbed my way through the manual and decided I could use the space for something else.

F. Guffey

F. Guffey

JeepHammer · December 21, 2016, 06:12 PM

My speil choker hates me...

This is going to devolve into a semantics argument, like most questions on this forum, and the OP is going to be lost in all the chatter like usual.

The case headspace gauge shown above (steel tube) Will give you a brass that is (more or less) SAAMI specification.
You simply take a FIRED brass, measure it with a Datum Line adapter,
Then bump the shoulder back a couple thousands at a time until it fits the chamber.
This is YOUR working headspace for that particular rifle.

Once the case SIDES are pushed in far enough the Datum Line lands on the taper in the case gauge,
Then you can use a caliper to measure the case gauge & inserted case together,
OR,
You can keep using the Datum Line adapter & caliper to measure.

To bump a shoulder easily 0.002",
Anneal the case shoulder/neck, torch is OK,
This makes the case MUCH softer, and it stays where you bend it instead of 'Springing Back',

Use automotive feeler gauges between case & shell holder, under the case.
This will allow you to 'Bump' 0.001" or 0.002" without trying to mess with re-setting the die in the press as many times.
Most of the shell holders will let you have 0.005" or more with just feeler gauges.
Cheap, effective & available at any auto parts store.

F. Guffey · December 21, 2016, 06:21 PM

Quote:

Most of the shell holders will let you have 0.005" or more with just feeler gauges.

My favorite shell holder is the one sold by RCBS, they are my favorite because I use them to shorten a case for short chambers .011" shorter than minimum length. And then there is the other reason, when a case whips my press because the case had more resistance to sizing I increase the presses' ability to overcoming the cases ability by raising the case off of the deck of the shell holder. So I use a feeler gage to decrease the deck height of the shell holder instead of grinding the top pf the shell holder or bottom of the die.

F. Guffey

JeepHammer · December 21, 2016, 06:25 PM

Mr. Guffey is correct about the Wilson case gauge being a Datum Line based gauge,

I'm not about to try and explain how EDM (Electronic Discharge Machining) works to this bunch!
This thread is already confused & convoluted enough!
Just suffice to say current EDM can give tolerances to the MILLIONTHS of an inch with the right equipment... Super Accurate.

Suffice to say the LE Wilson gauge has a LOT of functions,
Not the least of which is Datum Reference case length indicator, both MINIMUM & maximum for SAAMI specification,

Datum Line forward for case neck length Minimum/Maximum,
And for chambers that aren't cut grossly oversized around the body of the case, can be used as a datum referenced over length (fired) case gauge.

Some chambers are just so over bored the case swells too much for the gauge.
That's where a Datum Line adapter for your caliper comes in,
Works no matter how bloated the case is and won't give false readings because a bloated case can't reach the Datum Line in the case gauge.

The two 'Bullet' shaped gauges are for 'Go/NoGo' only, they serve no functional purpose to reloaders.

December 20, 2016, 02:50 PM	#10
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Bytesniffer, A chamber's headspace is a measure of how much room it has for a cartridge case, and excess headspace is the amount of room the chamber has for a cartridge case to rattle back and forth in the chamber. The bullet is not involved at all. I think the fact some people use the word "head" to mean "bullet" has perhaps caused your confusion. The "head" in headspace refers to the pressure head formed by the brass at the breech end of the gun. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 21, 2016, 04:14 PM	#20
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Headspace is a chamber characteristic, and a gun still has a headspace value whether it is within any accepted tolerance or not. There is a standard headspace tolerance for each chambering for new guns, but there is also a field reject headspace tolerance limit that is outside the manufacturing tolerance and which armorers and gunsmiths use to decide when a barrel needs to be replaced or set back and rechambered. All this, however, is only necessary for remaining on good terms with commercial cartridge standards. Many a wildcatter has changed the headspace in his chamber to something nobody else in the world uses, but his chamber still has headspace. Anyone with headspace outside the manufacturing tolerances can load fire-formed cases to match it, as if it were a wildcat, and they still have headspace. The case gauge determines if a case will fit inside a chamber with new-gun minimum tolerance headspace. An indirect headspace gauge, like the case thimble of the RCBS Precision Mic, is making what is called an indirect or take-off measurement of the headspace of a chamber by examining what size a case fire-forms to inside the chamber. Due to brass spring-back, this is not a precise measurement. Like any indirect measurement made by measuring dimensional mirroring by an intermediary, the error in the intermediary has to be added to the measurement error. In this case the intermediary is the fire-formed case, which is typically a thousandth smaller than the chamber. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 19, 2016, 09:02 PM	#1
Bytesniffer Member Join Date: November 29, 2016 Location: Long island ny Posts: 67	How should I determine headspace. I was thinking Take a trimmed sized Case 7.62 2.008 Neck lightly crimped Put bullet in case And chamber , slowly Until bullet is pushed on to Lands and into case. After removing round then back off A few thousand's. Any reason why this Wouldn't work ?

December 19, 2016, 11:10 PM	#2
firewrench044 Senior Member Join Date: July 9, 2007 Location: Fort Pierce, Florida Posts: 381	You may need to remove the ejector from the bolt to get an accurate size Many have done it that way before

December 19, 2016, 11:22 PM	#3
5whiskey Senior Member Join Date: October 23, 2005 Location: US Posts: 3,753	OK you're not talking about headspace there, you're referring to seating depth in reference to the rifling. I would start by seating long, then gradually seat deeper. I mark the projectile with a sharpie, and seat gradually deeper until the rifling leaves no smudges or marks on the sharpie colored portion. Once I find that point, I usually seat at least .02 deeper, and that is quite close. Some rifles like a longer "jump" to the lands. Some like a very short distance, but beware that seating to close to the lands can increase pressure. Hence, why I'm at least .02 off.

December 19, 2016, 11:55 PM	#4
RKG Senior Member Join Date: June 18, 2009 Location: Boston Posts: 569	http://m.hornady.com/store/Lock-N-Lo...traight-1Each/

December 20, 2016, 12:35 PM	#8
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	I am the fan of shop skills. if you have mastered the .002" bump you should be able to master the .004" bump and the .006" bump and the .008" bump and the .010" pump. I go beyond the 'bump the shoulder', fact is I find it most difficult but when sizing a case and controlling the length of the case from the shoulder of the case to the case head I sized the cases in thousandths. I form short chamber cases, I form long chamber cases. And then there are methods a reloader could use when determining the length of the chamber from the shoulder to the bolt face in thousandths. F. Guffey

December 20, 2016, 12:39 PM	#9
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	But; before the bump the reloader must be able to determine the length of the case from the shoulder to the case head. My favorite case is the case that requires .014" bump to get it to minimum length/full length sized, and I believe it important the reloader knows what a minimum length/full length sized case is. F. Guffey

December 20, 2016, 09:19 PM	#12
JeepHammer Junior member Join Date: February 27, 2015 Posts: 1,768	Headspace: From base of case against bolt face to 'Datum Line' on case shoulder. Picture is worth 1,000 words, http://i1298.photobucket.com/albums/...ps8j7sg7xk.jpg Bullet seating depth is what you described. Seating depth determines how far off the rifling the bullet sets. Neck length is determined from 'Datum Line' to neck mouth, where the bullets fits into the case. All a neck does is hold the bullet center with the bore, so neck length under 'Maximum' isn't a big deal.

December 20, 2016, 09:27 PM	#13
JeepHammer Junior member Join Date: February 27, 2015 Posts: 1,768	With a properly sized case (Start with SAAMI for point of reference or 'Zero' point) your particular chamber could be +/- SAAMI specification. Most chambers are not exact. With a factory case that passes in a headspace gauge, Simply oil the bolt face, Insert a factory round in the chamber, Use 'Plastic-Gauge' on the case head, Carefully close, then open the bolt. Plastic-gauge is a plastic fillies that that flattens out at a specific rate, and holds its shape so you can determine compression. Available for cheap at any auto parts store... The case headspace, plus what the plasti-gauge tells you will give you a very close reading of the actual headspace length of your chamber for a couple bucks.

December 20, 2016, 09:33 PM	#14
JeepHammer Junior member Join Date: February 27, 2015 Posts: 1,768	To be more precise, you will need speciality tools. A Datum Line adapter on your caliper to be precise. Use the standard LE Wilson (or comparable) heads space go/nogo gauge to produce a brass sized a little long, Keep bumping the shoulder back & measuring the brass with caliper/Datum Line adapter until the case fits into the chamber with no effort/extra pressure on the bolt when compared to an empty chamber. At the point the shoulder is bumped back far enough the bolt closes with no ADDED resistance, you have found your particular headspace length.

December 21, 2016, 12:01 AM	#16
firewrench044 Senior Member Join Date: July 9, 2007 Location: Fort Pierce, Florida Posts: 381	Bvtesniffer -- In most rifles the ejector is in the bolt it will put sideways tension on the cartridge sometimes a little sometimes a lot that tension can (not always ) cause you to get a false reading It is usually easy to remove the ejector and eliminate that possible problem ( just don't let it fly across the room, put a rag there and catch it ) Also some extractors do not hold the cartridge tight against the bolt and the spring tension of the ejector pushes the cartridge away from the bolt again giving you a false reading

December 21, 2016, 05:31 AM	#17
firewrench044 Senior Member Join Date: July 9, 2007 Location: Fort Pierce, Florida Posts: 381	Have sent a message call me I will clarify this stuff on the phone I have tried to post answers twice and it will not go through

December 21, 2016, 03:22 PM	#18
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	Headspace is a rifle manufacturing tolerance that has nothing to do with the cartridge. The standard LE Wilson (or comparable) headspace go/no-go gauge is not a headspace gauge. Cartridges do not have headspace. The Wilson thingy is a case length gauge. "...some extractors do not hold the cartridge tight against the bolt..." Isn't what the extractor is for. "...an Ishapore Enfield..." Really expensive things to fix headspace on. Requires a handful of bolt heads(no numbers on 'em) and proper headspace gauges. Doesn't require a new barrel.

December 21, 2016, 04:12 PM	#19
Reloadron Senior Member Join Date: June 8, 2016 Location: Cleveland, Ohio Suburbs Posts: 1,756	Something about one picture is worth... comes to mind. I believe what the original poster had in mind as a case gauge of sorts and was concerned with bullet seating depth or how far to seat off the lands. Regardless, there are likely a dozen case gauge variations out there to be had, LE Wilson and Forrester come to mind, assorted seating gauges Hornady and RCBS off the top and finallt headspace gauges which as mentioned are a chamber gauge and have nothing to do with cartridges or cases. Ron

December 21, 2016, 05:22 PM	#21
firewrench044 Senior Member Join Date: July 9, 2007 Location: Fort Pierce, Florida Posts: 381	Bytesniffer -- Head space -- is the distance between the case and chamber Distance to lands (or jump ) -- is distance between bullet and rifling (or lands) I think you are after the Distance to lands ( jump ) I believe your mistake in terminology has many in this thread answering the wrong question To use a case and bullet to determine Distance to lands do not crimp bullet make 4 cuts in the case neck (so the bullet moves very freely with minor resistance ) after putting bullet into chamber and closing the bolt gently remove the bullet and measure the length of the cartridge from base to the oglive ( you need a special tool ) ( oglive is the place on the bullet where it touches the lands ) Hornady makes that tool, RCBS also makes it, it comes in a set ( that is what I use -- RCBS Precision MIC. 308 WIN. P/N -- 88329 , the set has 3 tools with good instructions and good illustrations ) Please forgive my spelling, I am a mechanic, I can make your car, light truck, medium truck, semi or firetruck dance ( certified in all ) but spelling is sometimes beyond me

December 21, 2016, 06:12 PM	#23
JeepHammer Junior member Join Date: February 27, 2015 Posts: 1,768	My speil choker hates me... This is going to devolve into a semantics argument, like most questions on this forum, and the OP is going to be lost in all the chatter like usual. The case headspace gauge shown above (steel tube) Will give you a brass that is (more or less) SAAMI specification. You simply take a FIRED brass, measure it with a Datum Line adapter, Then bump the shoulder back a couple thousands at a time until it fits the chamber. This is YOUR working headspace for that particular rifle. Once the case SIDES are pushed in far enough the Datum Line lands on the taper in the case gauge, Then you can use a caliper to measure the case gauge & inserted case together, OR, You can keep using the Datum Line adapter & caliper to measure. To bump a shoulder easily 0.002", Anneal the case shoulder/neck, torch is OK, This makes the case MUCH softer, and it stays where you bend it instead of 'Springing Back', Use automotive feeler gauges between case & shell holder, under the case. This will allow you to 'Bump' 0.001" or 0.002" without trying to mess with re-setting the die in the press as many times. Most of the shell holders will let you have 0.005" or more with just feeler gauges. Cheap, effective & available at any auto parts store.

December 21, 2016, 06:25 PM	#25
JeepHammer Junior member Join Date: February 27, 2015 Posts: 1,768	Mr. Guffey is correct about the Wilson case gauge being a Datum Line based gauge, I'm not about to try and explain how EDM (Electronic Discharge Machining) works to this bunch! This thread is already confused & convoluted enough! Just suffice to say current EDM can give tolerances to the MILLIONTHS of an inch with the right equipment... Super Accurate. Suffice to say the LE Wilson gauge has a LOT of functions, Not the least of which is Datum Reference case length indicator, both MINIMUM & maximum for SAAMI specification, Datum Line forward for case neck length Minimum/Maximum, And for chambers that aren't cut grossly oversized around the body of the case, can be used as a datum referenced over length (fired) case gauge. Some chambers are just so over bored the case swells too much for the gauge. That's where a Datum Line adapter for your caliper comes in, Works no matter how bloated the case is and won't give false readings because a bloated case can't reach the Datum Line in the case gauge. The two 'Bullet' shaped gauges are for 'Go/NoGo' only, they serve no functional purpose to reloaders.