Hornady headspace tool

[ratbuster]

I have seen several sources state a .223 Go gauge is 1.464" (both PTG and Forster) yet when I measure factory .223 ammo or fired .223 brass with my Hornady headspace tool I get around 1.455".

Does the Hornady tool provide a measurement that is different to other available headspace tools?

Does anyone know the dimension for a PT&G 20 VT Go gauge? If so I would like to compare that dimension to what I get on my VT gauge.

Thanks,

Phil

 

[Ggmac]

What measurement do you get using the Hornady on the go gauge ?

 

[Patch700]

Something for you to ponder.... Let's assume the opening of the hornady bushing is .330". And lets say we measure a case at the shoulder datum and come up with a number that reads 1.850" or whatever it may be.

Now lets take that same insert and open the hole up .001" , now re measure the same case.. That 1.850" number we first acheived is now quite a bit less isn't it.. And alot more than just the .001" that we opened up the comparator to...

You can see where I'm going with this i hope... Not all hornady aluminum comparators are going to read the same.

 

[primer popper]

My PTG 20 Vartarg go gauge measures 1.077" headspace, using Hornady tool.

 

[ratbuster]

I get 1.085" on the 20VT go gauge...

Patch: Your explanation makes perfect sense.

 

[ratbuster]

Has anyone seen a stated length spec on a PTG Vartarg Go Gauge?

 

[Patch700]

Is the 20 vt not simply a 223 necked down to 20? If it is and retains the same shoulder angle then the two cases would have the same datum line... Same as a 22-250 and 250 savage or a 6,7 or 30br would all share the same datum line measurement.

I'm not sure the reasoning behind the question but if this is pertaing to you headspacing a prefit then there are a couple other things to know besides what the go gauge measurement is ... A go gauge at a specific number does not mean that certain amunition out there will be at that number , it could be well under that number and would obviously still chamber.

In any event good luck with your findings and enjoy the holidays.

 

[ratbuster]

Patch: A 20 VT (Vartarg) is a 221FB necked to 20 cal and formed to 30 degree shoulder. I originally posted because i was wondering why my Hornady headspace guage measures 223 cases about .010 shorter than what PTG and Foster Go gauges are stated to be.

Your first post basically answered the question and Primer Popper confirmed it. Thanks for your thoughts

 

[fguffey]

Does the Hornady tool provide a measurement that is different to other available headspace tools?

I am the fan of transfers and standards, there was a time when it was suggested 'all you gotta do is go to your local hardware store and purchase bushings with holes in them' and then it finished with 'that is what I do'. Problem: The datum does not have a radius. The datum is a round hole with a very sharp edge. A datum? with a radius increases the measured length. I make datums, I am not worried about case friendly datums.

The Wilson case gage has a datum, it is case friendly, the datum in the Wilson case gage has a convexed radius.

reloaders need a standard, it begins with a datum with a very sharp edge.

F. Guffey

 

[amlevin]

I don't particularly care whether the Hornady Headspace gauge readings correlate with a true headspace gauge.

The tool is made to measure fired cases and help the reloader adjust the sizing die for shoulder bump.

If I fire a case several times and measure it with the Hornady tool, that's the "benchmark" for setting my sizing die to bump the shoulder.

Want to really mess with your mind, try to compare true headspace measurements with those you obtain using a sinclair insert for their version of the Hornady tool. The Sinclair includes some counterbore to allow the case to be aligned more squarely than what is possible with the Hornady.

Use the tool for what it's intended to do and if one is measuring the actual headspace in the rifle, use the tools designed for that purpose.

 

[fguffey]

I don't particularly care whether the Hornady Headspace gauge readings correlate with a true headspace gauge.

Reloaders have an infatuation with head space, seems every gage is a head space gage. I don't. the case does not have head space, any tool I use to measure the length of a case from the shoulder to the head of the case is a case length gage. I measure the length of the case from the shoulder to the case head before firing and again after firing. That makes my case gage a comparator.

Then there is the understanding of the concept of datum. In the fist 10 years of reloading on the Internet the datum was perceived as being a line with a rational: And that is how 'they' determine head space.

F. Guffey

 

[ireload2]

Hello Rat
I have a Hornady tool and use it a lot to compare a sized cases to fired cases.
The Hornady datum circle bushings are made of anodized aluminum. This is not a very tough material so they chamfered the datum circle hole to keep the gauge from changing and to protect the cases from being ringed by the anodizing on the aluminum.
The datum diameters are correct but the chamfer breaks the edge and changes the effective length of the gauge so that you cannot set it to an exact zero using Hornady's instructions. So there will be variations between the Hornady tool and a headspace gauge unless you change how you set (zero) the Hornady tool.

If you have a gunsmith's headspace gage for the caliber you want to measure, use it to set the Hornady tool.
Set the Hornady tool to the exact dimension marked on the headspace gauge.
You cannot use just any old gauge to set it. It must be for the same datum diameter and for the same shoulder angle.
So you can use the same gage for a .257 Roberts and a 7X57 but you cannot use that gauge for a 6mm Rem because of the different shoulder angle.

I find the Hornady tool very useful but to get real numbers to compare to a SAAMI drawing you need a sharp edge datum bushing or you need to set the guage with a gunsmith's headspace gauge.

I have seen several sources state a .223 Go gauge is 1.464" (both PTG and Forster) yet when I measure factory .223 ammo or fired .223 brass with my Hornady headspace tool I get around 1.455".

Does the Hornady tool provide a measurement that is different to other available headspace tools?

Does anyone know the dimension for a PT&G 20 VT Go gauge? If so I would like to compare that dimension to what I get on my VT gauge.

Thanks,

Phil