Minimum headspace question

[Texas10]

I suppose an argument could be made that setting up the chamber on the long side of spec, i.e., bolt closes stiff on the no-go gage, will result in fire formed brass with an increased internal capacity and thinner walls, resulting in lowered pressures and more room for powder. Maybe some one here has actually experimented with that idea and can add some data and conclusions.

And if your dies are set up to only move the brass enough to chamber the round again, brass life might not be too adversely effected.

The only "fly in the ointment" that I can see with that idea is this; what if the actual chamber diameter is on the large side of spec. If that's the case, you're going to be moving more brass with each sizing with resulting short brass life unless you have a die custom made to your chamber spec using your fire formed brass.

In the end, the relationship between your chamber and your die is what matters. And if you've exceeded the dies capability to adjust to your chamber, you may need to adjust your chamber to your die or buy another brand of die to get the performance you need.

[RC20]

I suppose an argument could be made that setting up the chamber on the long side of spec, i.e., bolt closes stiff on the no-go gage, will result in fire formed brass with an increased internal capacity and thinner walls, resulting in lowered pressures and more room for powder. Maybe some one here has actually experimented with that idea and can add some data and conclusions.

And if your dies are set up to only move the brass enough to chamber the round again, brass life might not be too adversely effected.

The only "fly in the ointment" that I can see with that idea is this; what if the actual chamber diameter is on the large side of spec. If that's the case, you're going to be moving more brass with each sizing with resulting short brass life unless you have a die custom made to your chamber spec using your fire formed brass.

In the end, the relationship between your chamber and your die is what matters. And if you've exceeded the dies capability to adjust to your chamber, you may need to adjust your chamber to your die or buy another brand of die to get the performance you need.

I don't see the miner brass difference making any difference in pressures. Case variance is more than that (assumes same case used). Different mfs and how thick the inteiroi is would make some difference. Had a discussion with someone on that, they said it was irrelevant (top shooter of some kind)

You chamber difference will be the shoulder, once its pushed out and if you minimum bump it, then that is not an issue

I have shot a lot of Model of 1917 30-06, its normal head space is almost to a field reject point (they did not care, they wanted the gun to shoot in mud and hot combat with carbon build up)

I segregate the brass now, but before I did that it was a non factor before (other than it would crack a bit sooner).

I haven't had any crack since I gave them their own fodder and do the minimum bump back per that case not the SAMMI spec Savage cases (now, I had a Sako at one time that was co shot with the 1917x)

Yes they also do some case sizing but its pretty small.

I will get some measurements next time I shoot the 1917.

As this is a work in progress the reloading has been adapting. Minimum shoulder bump back was one step over the old methods, annealing is another, I now have a neck sizer only die (which works really well) instead of the ball in the sizing die.

There are other things to do but I am doing one at a time as I get a system down and comfortable with it, then look at what seems to be the next step for either brass longevity (minimum bump back and annealing) or better accuracy (neck sizer)

Part of that is I need to keep up with my shooting needs and a significant change can disrupt the output.

[m12lrs]

I don't see the miner brass difference making any difference in pressures. Case variance is more than that (assumes same case used). Different mfs and how thick the inteiroi is would make some difference. Had a discussion with someone on that, they said it was irrelevant (top shooter of some kind)

You chamber difference will be the shoulder, once its pushed out and if you minimum bump it, then that is not an issue

I have shot a lot of Model of 1917 30-06, its normal head space is almost to a field reject point (they did not care, they wanted the gun to shoot in mud and hot combat with carbon build up)

I segregate the brass now, but before I did that it was a non factor before (other than it would crack a bit sooner).

I haven't had any crack since I gave them their own fodder and do the minimum bump back per that case not the SAMMI spec Savage cases (now, I had a Sako at one time that was co shot with the 1917x)

Yes they also do some case sizing but its pretty small.

I will get some measurements next time I shoot the 1917.

As this is a work in progress the reloading has been adapting. Minimum shoulder bump back was one step over the old methods, annealing is another, I now have a neck sizer only die (which works really well) instead of the ball in the sizing die.

There are other things to do but I am doing one at a time as I get a system down and comfortable with it, then look at what seems to be the next step for either brass longevity (minimum bump back and annealing) or better accuracy (neck sizer)

Part of that is I need to keep up with my shooting needs and a significant change can disrupt the output.

Here is an interesting.solution to the neck tension adjustment scenario

Whidden full length non bushing sizing die and his expander ball kit

http://www.whiddengunworks.com/produ...kits-and-sets/

http://www.whiddengunworks.com/product/sizer-die-only/