Determining Headspace ETC... ETC

[lyman]

From BC " It all depends on what the meaning of is is".

[fguffey]

Purchased mine from Sinclair and I am well pleased. FWIW

Sinclair and Hornady had a problem with their methods and technuiques when making gages. Helping Sinclair or Hornady with suggestions did not work; years ago Jimmy Dean talked about getting the opossum across the road safely. He thought it would help if he was able to convised the possum ‘IT COULD BE DONE”.

So he asked: “Why did the chicken cross the road?”, as expected no one knew so he explained; the chicken crossed the road to show the opossum it could be done.

Well there is no showing Hornady/Sinclair it can be done. A reloader can not verity the accuracy of the Hornady comparator, information gathered from the tool does not agree with any reloading manuel or SAAMI.

‘WHY?’ The hole in the tool is not a datum, the hole in the tool has a radius, I understand no one understands what that means but the datum does not have a radius; my datums have sharp edgesm my datums are not case friendly.

Back to the Wilson case gage, the Wilson Company uses datum with a raius but they understood how to make a tool that could be verified. The first case gage I examined got the treatment, I stood the gage on a block of lead and then drove a case into it; when finsished the case head was .100” below the open end of the gage, after driving the case gage the datum with the radius was well defined.

L.E. Wilson, what a bunch of geniouses.

Again, I make datums, I have purchased datums, my datums are not case friendly, I have a grinder, I can use it to make pilots, I can grind angles and I gan grind ‘to length’. If it was necessary to shorten a die and or lower the deck height of a shell holder I have the grinder if it was necessary. Problem, when the cases are removed from my press I can determine if the case was sized, nothing special but I can determine if the case is full length sized before I lower the ram amd I can determine if it necessary to grind the bottom of a die and or shell holder.

F. Guffey

[JOHN COOK]

Again, I make datums, I have purchased datums, my datums are not case friendly, I have a grinder, I can use it to make pilots, I can grind angles and I gan grind ‘to length’. If it was necessary to shorten a die and or lower the deck height of a shell holder I have the grinder if it was necessary. Problem, when the cases are removed from my press I can determine if the case was sized, nothing special but I can determine if the case is full length sized before I lower the ram amd I can determine if it necessary to grind the bottom of a die and or shell holder.

Guffey, you should be working for NASA. I knew when I posted about the photo in the American Rifleman I was on thin ice. I knew you would not be able to pass up an opportunity to show us all your knowledge on headspace. It's the same rhetoric as your pass posts. S A A M I drawings shows the chamber of a 30:06 Datum line being .375 ( that is a diagonal dimension) and labels it HEADSPACE DIMENSION . The length from this Datum line to the base of the cartridge, as shown on the drawing, is
2.048 Min. and 2.0587 Max. It states very clearly that this is required to get proper Headspace on the 30:06. On the same page is a drawing showing dimension for the 30:06 cartridge. It shows the Datum line being .375 Basic. You are correct, the drawing does not refer to headspace. This drawing also shows the Dimension of 2.0526- .0070. from the Datum line to the base of the cartridge. A little math and it shows the Datum line on the cartridge can be 2.0526 and minus .0070 which gives you a length of 2.0456. It is very clear to me the .375 Datum line being the same on both drawing is relevant.

By the way since you can BUY Datums , please send me a box full. I wish to reload next week and you can never have to many DATUMS.. I'm done with this.

john in SC

[nf1e]

Getting involved in the technical mumbo jumbo could really take the fun out of the hobby. I would much rather hear comments from grass roots loaders if there are any left on this side of the sod.
The Boogie Woogie google boys are welcome to their slide rules and fancy jargon. Doesn't make my ammo shoot any better and that's all I have been interested in.

[fguffey]

Guffey, you should be working for NASA. I knew when I posted about the photo in the American Rifleman I was on thin ice. I knew you would not be able to pass up an opportunity to show us all your knowledge on headspace. It's the same rhetoric as your pass posts. S A A M I drawings shows the chamber of a 30:06 Datum line being .375 ( that is a diagonal dimension) and labels it HEADSPACE DIMENSION

I off set the length of the chamber with the length of the case, for me it is easy because I measure the length of the case from the datum to the case head. The only way that is possible is to know the length of the chamber from the datum/shoulder to the bolt face.

Reloaders and smiths though that was all that was required, they did not have a clue. The datum is a round hole, the datum is a circle, the round hole for the 30/06 is 3/8” or a .375” diameter circle.

‘HEADSPACE DIMENTION’ “and that is how they do it” ? A reloaders needs to know the diameter of the diameter of the datum to determine the length of the chamber; and length of the case from the datum to the case head. A smith/reloader that can drill a round hole with a diameter of .375” and can verify ‘ZERO’ can determine the length of the case from the datum to the case head.

It has nothing to do with me not being impresses with all of your numbers; all we are doing is measuring from a datum; the datum must be ‘ZERO’. Back to Hornady and Sinclair, they use a radius on the datum; the radius puts the datum/diagonal below zero.

‘Back to my same old rhetoric’ L.C. Wilson has been making case gages for over 81 years, during all of that time they have used a radius on the datum based case gage. A reloader is not required to think when using a case gage because Wilson grinds the case gage to the correct length for minimum length sized cases and cases that are go-gage length from the shoulder to the case head. But to most reloaders the Wilson case gage is a drop-in gage.

To verify the Hornady comparator the reloaders should be able to determine if the tool can be zeroed. I have no interest in breaking anyones mind bit there are transfeers and standards like the headspace gage that can be used to verify.

Life for me is much more simpler because I do not use a radius on the datum. In the real world the hole in the datum is drilled undersized and then renamed to diameter. I know, reloaders just love their Sinclair/Hornady comparator.

I was thinking about a new datum based tool yesterday, and then I decided there is not one reloader on this forum or any other forum that would understand the function of the tool or appreciated the speed.

F. Guffey

- - - Updated - - -

Guffey, you should be working for NASA.

Forgive, thank you.

F. Guffey

[nf1e]

Well, I guess that's that then.
Back to the loading bench tho old fashioned way.
Some live in a very lonely world by choice.

[togor]

Is that a Canadian joke?

If not I have been doing it wrong for over 50 years my friend. This is a critical measurement that is easily checked with proper equipment. There is chamber headspace measurement and cartridge headspace measurement. I like to set my cartridge headspace .004 under chamber headspace for auto-loaders and a little tighter for bolt rifles.

Headspace = distance between the bolt face and a datum line (determined by SAAMI) where the front of the cartridge rests on its shoulder when the bolt is closed.

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough.

[nf1e]

Can't make it so easy, everyone would want to join the foray. Maintaining the mystique should be left to the most creative minds that like to ruin everything with technical interpretations that only a few could possibly understand, and normal folks could care less. I just like things as they appear to be, not as they truly are.

[lyman]

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough.

many moons ago I was a true believer,
set to SAAMI spec, and if a firearm failed headspace then part it out, rebarrel, etc etc , it was toast,
whoa is me, etc etc


then, when I started reloading (not quite as many moons ago, but a good while ago) I learned different,

load safe, watch for pressure signs, enjoy

[fguffey]

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough

. Togar, The difference in length between the 8MM 57 and the 30/06 from the datum/shoulder to the bolt face is .127” (+/- a few.) I understand the instructions for forming 30/06 cases to 8 MM 57 cases start with “All you got to do is etc. etc.”, after that the honesty of the reloaders goes out the window.

I have formed thousands of 8MM57 cases from 30/06 cases because; after the forming die is paid for 8MM57 cases cost me seven cents each. Without the forming dies the cost goes out of sight. Without the forming die the cases look as bad as roll your own cigarettes.

I have long chambers; because I have no phobia about ‘the datum’ I determine the length of the long chamber from the shoulder/datum to the bolt face. After determining the length of the chamber from the shoulder to the bolt face I adjust the forming die to off set the length of the chamber when forming cases; as we (all should know) after forming the case must be sized for final fit. I have asked many times where the .002” die adjustment come from did.

And I always ask how can a reloader miss when the parent case is .127” longer than the case being formed from the shoulder of the case to the case head? This questions has cause many reloaders to have sagging shoulders and a reseeding hair line. Not my fault. In the beginning I used .003”.

F. Guffey