Shoulder Setback & Die Bottoming Out

[huckberry668]

Phil, it sounds like your chamber is within spec and it's a good thing.

this is what I meant to say. based on your measurements and examples, if the fired cases came out 1.273" and it's shorter than the Go gauge then the chamber is most definitely out of spec too short and you wouldn't want that.

In that case, you wouldn't expect a sizing die to be able to size case length to 1.270".

[ar15barrels]

I am new to reloading, shoot an AR15 in 223 Remington, and have a question regarding shoulder setback and the Redding full length sizing die bottoming out on my Forster C-Ax press shellholder jaws.

Using some Sinclair tools, the average length of fired cases is 1.277". The actual measurement is not relevant...it is odd because of the attachments on the measuring calipers. I carefully adjusted the die downwards a bit at a time, measuring the case until it measured 1.274", so as to give about .003" clearance between the shoulder and the chamber.

I found that to achieve the 1.274" dimension the die was bottomed out on the press shell holder jaws. It would not be possible to push the shoulder back any more since you can not screw the die down any further. This seems very odd to me. What if the rifle had fired shells that were 1.273". Trying to set the shoulder back to 1.270" (.003" clearance), would be impossible.

All this seems to indicate a very tight chamber, and perhaps it is. It is a Krieger barrel chambered in 223 Remington, not 5.56.

Please educate me on what I may be missing here.

- Phil

The missing link in your picture is that the press frame STRETCHES during sizing.
So, while the die is fully contacting the shellplate without a case being sized, when you are actually sizing cases, you will find that there's actually a gap between the die and the shellplate.
It may be a very small gap, only 0.003" to 0.005", but that's enough to allow you to screw the die down further and get the sized shoulder lengths that you need.

In very rare cases, you will absolutely "run out of die" and that's a problem with the sizing die that needs fixing.