How should I determine headspace.

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

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
 
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.
 
This makes the case MUCH softer, and it stays where you bend it instead of 'Springing Back',
Click to expand...

And then there are reloaders that assume the case has jump back, snap back or spring back. I have no ideal who started that "repeat after me" and I have no interest in doing a search.

But I believe we could sort fact from fiction and truth from nonsense if we measured. As I have said I have use the feeler gage 'forever' and when the case whips my press and the shell holder does not make it to the bottom of the die I measure the gap between the top of the shell holder and bottom of the die. I have no clue as to why reloaders are required to start over ever day. I adjust my dies ever time I use them, if I adjust my die to the shell holder with an additional 1/2 turn after contact when sizing a case the die should make it to the shell holder. If the shell holder does not make it to the shell holder the case did not get shoved into the die and if I want to know 'by how much' I measure the gap.

I am not the fan of blaming 'spring back' for everything. It just don't sound correct; ' boy! you got spring back:eek:'.

F. Guffey
 
Mr. Guffy:
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.
Click to expand...

Yes, I could drop a headspace gauge into the case gauge and actually have done it and noted using my steel pocket rule as a straight edge the gaps.

All of this headspace nonsense is here nor there as if we read the original post the original poster while using the term headspace "How should I determine headspace" was not actually looking for anything remotely related to headspace. Headspace aside, even the Wilson Case Gauge (or similar) will not get the original poster where he wants to be. His question which seems to involve chamber lede or free bore was pretty well covered back some time ago.

Heck, if it would be beneficial we could start a thread about case gauges and discuss them or we could discuss head space gauges. I just don't see much point to dragging either type gauge into this thread.

Ron
 
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.
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I agree, post #7 was answering a question as to why 'it' would not work.

I started out saying there is a difference between comparators and head space gages. 10+ years ago and I was being told by reloaders that sounded Wallace Berry; "It's OK there little buddy everyone on the reloading forum knows and understands what the other reloader is saying". And then there was that part about the case not having head space, and again the voice of Wallace Berry; that one sounded like; "it only matters to you".

F. Guffey
 
And for those of us who still remember...
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Mehavey thank you for that, my third choice was a western and then my second choice was a war movie; my first choice was anything with Wallace Berry.

And then there is the assumption members make; there is a good chance they are being had. I do not know but wonder if Bytesniffer is typing from the narrow end of his key board.

F. Guffey
 
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