Relatively new to reloading. A question: When a round is fired, has the brass shoulder been expanded against the chamber? If so, is this a good measure of this rifle's headspace, using a headspace guage such as a Hornady cartridge headspace guage?

Thats a good measure for reloading. Which is all it would ever be used for.

If you want to verify the chamber a proper headspace gage set must be used. That is a Go gage, a No go gage, and possibly a Field gage.

quote:

Originally posted by hdog:
Relatively new to reloading. A question: When a round is fired, has the brass shoulder been expanded against the chamber? If so, is this a good measure of this rifle's headspace, using a headspace guage such as a Hornady cartridge headspace guage?

There is a technique that I have developed using the Hornady tool (actually mine is the older Stony Point) that permits measurement of the chamber.

Basically I expand a case or use a longer case or case with a larger mouth than the original.

1. Using my sizer die I push the over lenght shoulder back until it will chamber in the rifle with just a light drag as you close the bolt. By light drag I mean only an ounce or two close pressure on the bolt handle.
2. Double check by pushing the bolt handle fore and aft. If it is still too tight use the Hornady tool to adjust your sizer down another .001 or so. Keep trying until you get it just right.
3. Check by slowly sizing several cases. Check them with the Hornady tool then check in the rifle. If you size one too short set it aside and get a longer one.
4. After burning up 4 or 5 cases on 2 or 3 different rifles you will have the technique down.

I have tested this on more rifles than I can count. Including some that you cannot easily find gauges for.

How do I know it works?
I have compared the tool measurement by measuring head space gauges with it. I have also measured the same cases at work at 20X with a 40" optical comparator.

Naturally this does not work on cases with no shoulder or poorly defined shoulders.

Thanks guys for your replies. I will be reloading 338 Lapua's for my son-in-law. He will be shooting in matches. I'm just trying to get as much control of variables as I can.

hdog,
Just keep a note book. Fired cases that have been reloaded and work hardened may retract from the chamber .001 to .002 when fired and not give a perfect transfer of the measurement.

With a little experience you will be about to measure a case that is .001 too long and will take a really heavy hand to close the bolt on.

You will also be able to see that sizing of the case will be affected by several things.

1. Variations in the amount of lube
2. Hardness of the case
3. If you shoot several rifles of the same caliber - the chambers vary and therefore the size of the brass before it is resized
4. Speed of the resizing stroke
5. Dwell of the press at full stroke during resizing
6. Double stroking of the resizing cycle.

All of the above affect the size of the case from head to shoulder.

The amount of lube needs to be adequate to generous without causing dents.

The sizing stroke needs to be slow and deliberate with a dwell at full stroke to let the brass completely move and take a set.

Retract the case, rotate it and re-stroke the press and size the case slowly a second time with a second dwell.

These techniques will permit you to control the headspace on your sized brass to the limit that you can measure it with your calipers.

Thanks SR4759,
There sure are a lot of actions in resizing that I would never have thought would have that much affect.

Thanks again,

Hdog,
I noticed the variations when forming brass to just barely drag. Until I could measure with the Stoney point tool I did not understand what was causing the variations.