Adjusting OAL for different Headspace.

bakerboy

bakerboy

New member
I resize my cases to 0 headspace in a case gauge. All new brass measures minus .004 in the case gauge and (also) functions fine. The test case provided by Stoney Point for use with it's OAL gauge measures minus .004 in the case gauge as well. Question? Is not the minus .004 case further into the chamber than my usual 0 headspace cases....... thus requiring a .004 adjustment in the OAL number measured with the Stoney Point gauge in order to achieve a .010 jump ?
 
I think you're measuring from both ends so the numbers won't mean exactly what you'd expect. I wouldn't worry about a bit further jump first time shooting them. Once the cases are formed the numbers will start being meaningful again.

peace.
unloaded
 
Quote:
I think you're measuring from both ends so the numbers won't mean exactly what you'd expect. I wouldn't worry about a bit further jump first time shooting them. Once the cases are formed the numbers will start being meaningful again.

peace.
unloaded



I cannot fire form the Stoney Point test case, so it will forever be minus .004. Let me phrase the question differently. Does case headspace affect OAL? If the answer is yes (which I think is the case) then I should adjust my OAL by .004 to shoot 0 headspace cases.
 
Quote:
Quote:
I think you're measuring from both ends so the numbers won't mean exactly what you'd expect. I wouldn't worry about a bit further jump first time shooting them. Once the cases are formed the numbers will start being meaningful again.

peace.
unloaded



I cannot fire form the Stoney Point test case, so it will forever be minus .004. Let me phrase the question differently. Does case headspace affect OAL? If the answer is yes (which I think is the case) then I should adjust my OAL by .004 to shoot 0 headspace cases.



The answer is no!

Headspace has nothing to do with OAL (Over all length, which is head to bullet tip).

Why do you think you have 4 thou headspace?

Why do you think you can make "0" headspace cases with a gauge?

.
 
Quote:
Quote:
Quote:
I think you're measuring from both ends so the numbers won't mean exactly what you'd expect. I wouldn't worry about a bit further jump first time shooting them. Once the cases are formed the numbers will start being meaningful again.

peace.
unloaded



I cannot fire form the Stoney Point test case, so it will forever be minus .004. Let me phrase the question differently. Does case headspace affect OAL? If the answer is yes (which I think is the case) then I should adjust my OAL by .004 to shoot 0 headspace cases.



The answer is no!

Headspace has nothing to do with OAL (Over all length, which is head to bullet tip).

Why do you think you have 4 thou headspace?

Why do you think you can make "0" headspace cases with a gauge?

.



Maybe i should have used jump instead of oal? If one case is fitting further into a chamber than another ( different case headspace) then the " jump" would be different.
 
Quote:
"... Maybe i should have used jump instead of oal? If one case is fitting further into a chamber than another ( different case headspace) then the "jump" would be different.



I think you are being a little Obsessive Compulsive about this.

A few thou will not make any difference... and your cases MUST be fired in your chamber so they have a minimum fit before you can do any of this stuff.

You need to test the loads to see what they want in the way of "jump or jam", and you will never be able to control it to the measurements you are referring to.

.
 
YUP.
Not all chambers are created equal.
Load & fire your virgin brass first and then worry about headspace when your resize them.

Bullet jump to the lands has NOTHING to do with headspace. Two rounds can be loaded to the same OAL in brass with different headspace measurements...
 
Quote:
YUP.
Two rounds can be loaded to the same OAL in brass with different headspace measurements...



That is my point.
There is case headspace which is the relationship of the case to the chamber and there is overall headspace
which includes the relationship of the bolt to the case.
If one case has a shoulder angle that lets the centerline of that shoulder protrude 004 further into the centerline of the chamber shoulder then that case when measured in a case gauge built at saami specs will read minus 4 assuming the same saami for your chamber. If your
OAL gauge case reads minus 4 in a case gauge then should you not adjust your jump 004 if you are using resized cases that read 0 in a case gauge?
 
Your extractor should hold your case aginst the bolt face so what your are talking about is meaningless. If it was to go all the way in like you are thinking you would have light firing pin strikes on your primer.
 
I think you are confusing/interchanging the shoulder length of the case with the acronym c.o.a.l. (cartridge over all length)...

C.o.a.l. is determined by measuring a case with the bullet seated (with calipers), from bullet tip to boltface. C.o.a.l. is a function of how deeply you seat the bullet into the case and is completely independant of headspace...

CASE length is the measurement of your brass (with calipers) from the mouth of the case to the boltface. It is also SAAMI spec'ed, according to caliber, with minimum and maximum measurements. It is also independant of headspace...

TO measure headspace, you need a tool that will measure the case from the neck/shoulder junction to the boltface. A case mic gauge will allow you to determine your chamber dimensions by measuring a 1X fired case from YOUR rifle according to a standard (SAAMI) length.

To prove this point, read on:

I have two 6X45 uppers. My 1X fired brass measures .004" LESS (at the shoulder) from my shorty upper as compared to 1X brass from my 20" upper. BUT I load rounds for both to the same c.o.a.l. (2.258")!

SO when I resize my brass, I must be sure to bump the shoulder back enough to account for that slight difference in HEADSPACE between the two. And I measure that with a case mic gauge to set my resize die accordingly...

Make sense???

As for bullets jumping to the lands, you need another tool to determine your chamber length to the lands. Then seat your bullet accordking to an ogive measurement from that particular bullet. This measurement has NOTHING to do with case/headspace measurements...
 
Quote:
Quote:
YUP.
Two rounds can be loaded to the same OAL in brass with different headspace measurements...



That is my point.
There is case headspace which is the relationship of the case to the chamber and there is overall headspace
which includes the relationship of the bolt to the case.
If one case has a shoulder angle that lets the centerline of that shoulder protrude 004 further into the centerline of the chamber shoulder then that case when measured in a case gauge built at saami specs will read minus 4 assuming the same saami for your chamber. If your
OAL gauge case reads minus 4 in a case gauge then should you not adjust your jump 004 if you are using resized cases that read 0 in a case gauge?



There is head space, and there is uhhh.... head space.

There is no such thing as "overall" headspace.

COL "Cartridge Overall Length" and OAL are the head to bullet tip measurement.

Headspace is the measurement from the head to a datum line on the case shoulder (or mouth).

There is no overall headspace.

The itty bitty space between the bolt face and the case head is the "working headspace", and this measurement is constantly changing as cases are fired and FL sized, or even fired and neck sized and fired again... so no one talks about it because it is never the same from one case to another, even if the cases are all fired in the same rifle.

If you want answers to questions, you cannot make up the words and phrases, because the thread will be turn into a discussion of what you mean (like this one has) rather than getting to your answer... /ubbthreads/images/graemlins/smiliesmack.gif


.
 
My guns don't seem able to detect a difference in .004. Perhaps it's my way of rejecting what I can't seem to control. To answer your question, well I can't, but your logic seems to "spot on" so personally I would adjust for that .004 jump.
Side note to Cat!! oh never mind.
 
Don't use headspace gauges to determine seating depth. Use the seating depth gauges. Yes, any difference in the length of your fired/sized case and the threaded case will show up at the other end because you are measuring from the bottom of the case to the datum line of the bullet. If the bottom of the threaded case is .004" less than your case, the seating depth will show up .004" less, too. Don't use OAL as bullets are notoriously inconsistent in their length and can screw up seating depth because of that.

Fast Ed
 
Quote:
Quote:
Quote:
YUP.
Two rounds can be loaded to the same OAL in brass with different headspace measurements...



That is my point.
There is case headspace which is the relationship of the case to the chamber and there is overall headspace
which includes the relationship of the bolt to the case.
If one case has a shoulder angle that lets the centerline of that shoulder protrude 004 further into the centerline of the chamber shoulder then that case when measured in a case gauge built at saami specs will read minus 4 assuming the same saami for your chamber. If your
OAL gauge case reads minus 4 in a case gauge then should you not adjust your jump 004 if you are using resized cases that read 0 in a case gauge?



There is head space, and there is uhhh.... head space.

There is no such thing as "overall" headspace.

COL "Cartridge Overall Length" and OAL are the head to bullet tip measurement.

Headspace is the measurement from the head to a datum line on the case shoulder (or mouth).

There is no overall headspace.

The itty bitty space between the bolt face and the case head is the "working headspace", and this measurement is constantly changing as cases are fired and FL sized, or even fired and neck sized and fired again... so no one talks about it because it is never the same from one case to another, even if the cases are all fired in the same rifle.

If you want answers to questions, you cannot make up the words and phrases, because the thread will be turn into a discussion of what you mean (like this one has) rather than getting to your answer... /ubbthreads/images/graemlins/smiliesmack.gif


.



Hey Cat lighten up on the guy /ubbthreads/images/graemlins/crazy.gif. He was a little confused so set him straight and send him on his way /ubbthreads/images/graemlins/grinning-smiley-003.gif. Dont beat him up then send him on his way.
 


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