When I have a barrel chambered I have them cut off a barrel stub, and short chamber it to make a chamber gauge. With that gauge I take a Piece of fired brass measure it with my calipers, I then size the brass, and place it back into the gauge, to see how much the brass was sized. (I can also measure other things with this stub, such as jamb length, neck specks length, and diameter and fit.)Originally Posted by chainsaw
I also use Harrell's dies, (Again good dies don't have to be expensive, Harrell's will do a custom fit neck bushing FL die for $70 bucks.) and Lynwood gives a small brass chamber gauge made of brass, that works the same way. unfortunately Harrell's doesn't make many different calibers of dies, on a handfull or two, and in them cases I exclusively use Forester dies. Also if I don't have a tight neck chamber where I need to change the bushing size, I use Forester. For example if you look at my avatar, that target and match win pin, was from the 2010 IBS 600 yard Nationals. The gun that I shot had a standard (No turn chamber) size chamber, and I loaded all my ammo with Forester dies. (FL Sizer, and Micrometer seater.)
In the past shooters measured set back by putting the bolt into the gun, (Most would remove the firring pin.) and closing it on the cartridge, They looked for a depth where the bolt would close with just a slight amount of tension feel on the bolt at the mid to bottom of the stroke. They would adjust the die until they found the spot, where the bolt would not just flop down on the sized brass.
Other tools can be used, (I can not say I have ever used them.) Sinclair and Hornady Both sell a headspace gauge that attaches to the caliper, and allows you to measure how much set back you have.
On my 6PPC I use shims under the die, so that I can closely change set back. I also only set me die to push the shoulder back .0005. In my other guns I strive for a .002 should bump back.
The reason why the brass that is full sized last so long is it is exercised, moved in and out but only a very small amount, this exercising of the brass actually makes it last longer. Now over working the brass (Excessive sizing) is what work hardens brass. One problem with neck sizing is the brass looses its rigidity, and will not go back into shape, This happens because the brass is not exercised. It develops a memory, and stays in that shape, even if you FL size it, it goes back to the same shape. So eventually the neck sized only brass looses it shape, and ability to go back to it. (Now this is after, many firings.)
No, not really, If you look at my brass that is out of my dies, you can see and tell that the entire brass has been sized. There is sizing marks all the way to the base.
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