I can't quite figure out the concept of the competition shell holders. The instructions say to start with .010 and then go to .008 etc. They say that .125 is the normal shellholder. So does .008 bump the shoulder more or less than the .010??
.008 bumps it more. Think of the number on the shellholder giving you a longer dimension on your head space gauge.....or the shellholder is that much thicker...whatever seems better.
I don't use mine much anymore....I just don't like the feeling of bumping the shellholder tight to the die.
Some folks figure bumping the shell holder squares the die with the shell holder and so with the case in the shell holder. Some folks square the case head to the case body too.
The numbers on the shell holders reference the .125 normal shell holder. The shell holder does not itself bump the shoulder of course but allows the die to come down the additional referenced distance. Given spring back and cam-over issues the results may not be a perfect match for the numbers.
I believe the competition shell holders to be a quick and generally successful way to arrive at a final setting with fewer trials and less scrapped brass than other systems of gage and turn a little bit but I don't believe the final result is any better. That is the Redding Instant Indicator - left set up in another press for ready reference - and the Redding competition shell holder set give a quick measurement and a quick adjustment at some extra cost for the convenience - and again all measurements are relative for the dial indicator and shell holder.
Thanks for all the responses!
What Clark says is very accurate...if the shellholder and die are bumping different rates of cam over can make the redding comp shellholders a little fuzzy to work with.
I use a hornady head space gauge and a rcbs head space mic to guide me. I've found different brands of brass might size different, harder brass after repeated use or annealed brass will also size a bit different.
I've used in the past the comp shellholders, and skips shim kit from Sinclair to make adjustments. What's working best for me now is a shaved shellholder that doesn't contact the die. I put a matching index mark on the die lockring and theads that represents about .002" head space for most brass. If I have to make an adjustment one way or another moving the marks apart about 1/4" corresponds to about a..004" change in head space. So basically I'm back to moving the lockring to make adjustments...but my marks make it fast and pretty accurate. Funny how you can come full circle sometimes.
Also re head space....I used to cycle the case through the sizing die pretty fast....I now hold the case up in the die at least 2 seconds... i feel this gives me a more uniform sizing...but not sure I can prove it.