Setting headspace with FL sizing die

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b_w.

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Hi everyone. Just setting up to do some reloading for my RPR in 308 and are trying to figure out how to set the head space. I have a bunch of once fired Federal brass from the RPR, a lot of once fired IVI I bought and new unfired Lapua brass. I am using a CO Ax Press with Forster National Match 308 full length die and measuring with a RCBS head space gauge.

With the RCBS gauge the once Federal Gold Medal brass is measuring -0.003 compared to loaded ammo measuring -0.005.

The once fired American Eagle (still Federal brass) measures between -0.004 and -0.005. New loaded ammo measures the same.

Unfired Lapua brass is measuring between -0.004 an -0.005.

Am I right to read this that my RPR has a tight chamber and that I should be resizing brass to 0.001 and .002 below the largest once fired size which would be the FGGM at -0.003?

I already resized a bunch of the IVI brass down to -0.004 to -0.005 but figured I should check before doing more and getting onto the Lapua brass.

Thoughts are appreciated.
 
Forget the gauges and just set your dies until the cases chamber with slight resistance. Be aware that due to different brass qualities among the different brands your sizing die may have to be readjusted slightly to accommodate the differing hardness and spring-back of the different brands.
 
With a full length resizing die, I would keep it simple.

For brass fired in your gun, I would set the die high to resize only about 2/3 of the neck. Check that it chambers OK in your gun. If it does, then reload it that way until it no longer chambers easily. When it gets tight then measure the shoulder for headspace. Set your die to move that shoulder back 0.001 to 0.002", and record that number. Once you have done this, then go back to partial resizing the neck until it gets tight again. And so on...

For fired brass not fired in your gun, I would do a full length resize with your die coming down hard on the shell holder. Then check it to see if it chambers. If it does then load and fire it, and proceed as above. If it does not chamber then throw it in the garbage.
 
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In my remington I remove the firing pin and set the die till the bolt closes, removing the firing pin/ striker assembly gives a better feel.
 
If you have cases fired from your rifle just measure the fired length of your cases and bump .001 to .002.

Measuring different brands of fired brass "may" give different fired lengths and you might have to average your sized length.

Are you using a RCBS precision mic?
 
b_w. said:
Yes, using RCBS Precision MIC.
Click to expand...

My .308 Precision Mic reads -.003 with a GO headspace gauge in the precision mic. I contacted RCBS and the gauge is only a comparator gauge, and not calibrated, meaning "Zero" is not minimum chamber headspace.

Bottom line measure a few fired cases and set your resizing die to bump the shoulder back .001 to .002.

Below a loaded unfired British surplus 7.62 NATO in the precision mic, reading -.002 (my GO gauge reads -.003)

IMGP51301-1.jpg


IMGP5254-1.jpg
 
When I FL size, I like to set the die deep enough that the die hits the shell holder hard and does not cam over. That way I know the die did its job.

But I don't like to over-size the brass. I have a set of shell holders (RCBS, I think) in 4 thou increments (I think) so that when the die hits the shell holder the case is not quite 100% sized.

I find the shellholder that sizes just enough that I feel a little bit of resistance as the bolt closes.

You can doe the same thing with a piece of shim stock on top of the shell holder.
 
Ganderite said:
When I FL size, I like to set the die deep enough that the die hits the shell holder hard and does not cam over. That way I know the die did its job.

But I don't like to over-size the brass. I have a set of shell holders (RCBS, I think) in 4 thou increments (I think) so that when the die hits the shell holder the case is not quite 100% sized.

I find the shellholder that sizes just enough that I feel a little bit of resistance as the bolt closes.

You can doe the same thing with a piece of shim stock on top of the shell holder.
Click to expand...

those are redding shell holders and they are in 2 thou increments, just be sure to got the right way so your not over sizing, or undersizing
 
b_w. said:
Hi everyone. Just setting up to do some reloading for my RPR in 308 and are trying to figure out how to set the head space. I have a bunch of once fired Federal brass from the RPR, a lot of once fired IVI I bought and new unfired Lapua brass. I am using a CO Ax Press with Forster National Match 308 full length die and measuring with a RCBS head space gauge.

With the RCBS gauge the once Federal Gold Medal brass is measuring -0.003 compared to loaded ammo measuring -0.005.

The once fired American Eagle (still Federal brass) measures between -0.004 and -0.005. New loaded ammo measures the same.

Unfired Lapua brass is measuring between -0.004 an -0.005.

Am I right to read this that my RPR has a tight chamber and that I should be resizing brass to 0.001 and .002 below the largest once fired size which would be the FGGM at -0.003?

I already resized a bunch of the IVI brass down to -0.004 to -0.005 but figured I should check before doing more and getting onto the Lapua brass.

Thoughts are appreciated.
Click to expand...

set the die touching the plate and then turn back half a turn, resize, chamber. Repeat the proceda with the die turn in 1/8 of a turn each time until the bass chamber with a little resistance. That's it.
 
#1 Rule: Don't assume your shoulder needs to be pushed back. Wait until you have fired the cases enough times that it starts to get harder to close the bolt. Then you know you have a case that is tight to the shoulder to measure. Then bump it 0.001 to 0.002". No need to rush into bumping it until it needs to be.
 
Thanks for the replies. So far I have only been sizing the once fired IVI military brass. I used the once fired in my rifle Federal brass to set the amount of resizing. I now understand that the RCBS Precision MIC is just for comparison. In order to bring the IVI into spec with the Federal I did have to cam over a decent amount. I was a little concerned at first but Forsters site says specifically that the press is designed for it.

Should I be running the new lapua brass through the sizing die or just leave it until its been fired?
 
I would not run new Lapua brass through the sizing die. If any necks are dented from shipping, I would deal with that before loading.
The IVI brass was probably fired in machineguns. Generous chambers. Make sure they chamber freely after you have sized them.
You may find capacity variations between the Lapua, IVI and Federal brass. This could affect your loads.
 
Lapua 308 brass has tight neck, 260Rem is super tight. I run them through an expander (multiple times for 260) otherwise seating depth is all over the place.
b_w. said:
...
Should I be running the new lapua brass through the sizing die or just leave it until its been fired?
Click to expand...
 
b_w. said:
Should I be running the new lapua brass through the sizing die or just leave it until its been fired?
Click to expand...

Yes, I would run the expander ball through the neck, but not far enough into the die to have the neck resized down. Just the expander ball only to make sure the ID is smooth and consistent in size. Also chamfer the OD and ID lip of the neck. If your run the neck through the sizing die you will just work the brass for nothing. And if you push the shoulder back (not likely) you will only make it worse, not better.
 
b_w. said:
Thanks for the replies. So far I have only been sizing the once fired IVI military brass. I used the once fired in my rifle Federal brass to set the amount of resizing. I now understand that the RCBS Precision MIC is just for comparison. In order to bring the IVI into spec with the Federal I did have to cam over a decent amount. I was a little concerned at first but Forsters site says specifically that the press is designed for it.

Should I be running the new lapua brass through the sizing die or just leave it until its been fired?
Click to expand...

Last night I was loading some new Winchester .243 cases, all I did was use a Sinclair expander mandrel die to expand and true the necks. If you do not have a mandrel die then just run the cases through a full length die as normal and trim and deburr the case. I have never found a new case that was too long in headspace, meaning full length resizing doesn't push the shoulder back as they are already shorter than minimum headspace.

Expander Mandrels and Neck Tension
http://www.accurateshooter.com/technical-articles/reloading/expander-mandrels-and-neck-tension/
 
I use the Redding competition shellholders. Use the ..010 over until there is a bit more
Bolt resistance than you want, then go down .002" at a time until
You get the bolt feel you want. Nothing to measure;
And besides, measuring has it limits. I can measure my feet,
But that can't replace trying on boots.
 
Dogleg said:
I use the Redding competition shellholders. Use the ..010 over until there is a bit more
Bolt resistance than you want, then go down .002" at a time until
You get the bolt feel you want. Nothing to measure;
And besides, measuring has it limits. I can measure my feet,
But that can't replace trying on boots.
Click to expand...

Yes, that will work. The cheaper option however is to simply short stroke the press so the case does not go all the way to shell holder contact. If you look at the case neck you can see how far down the neck is being sized. Just size 2/3 of the neck and continue that practice "until there is a bit more Bolt resistance then you want".
 
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