Setting up Forster benchrest sizing die help

[Clark]

I have 9 Bonanza sizer dies and 16 Forster.
None of them have the decapping stem installed.
I de cap with a Lee decapping die or a Lee collet neck.

There was a little fortune cookie strip of paper that came in my Sinclair concentricity gauge box that said ~ you will probably find the problem is the expander ball ~

After testing concentricity along the reloading process, I have found there are many contributors to cartridge eccentricity but the rest do not add up to as much trouble as the expander ball can make.

 

[bigedp51]

A picture is worth a thousand words......................

I also use a universal decaping die and then wet tumble before sizing.

I use a bore light and shine it in the vent hole and see where the spot of light hits the expander.

I adjust my expander higher so the case neck stays centered in the die longer. If the expander is adjusted too high you will feel the excessive force when expanding the case neck.

You can also buy the Forster expander and spindle assemblys and install them on your RCBS dies.

Below my RCBS .223 die with the Forster expander assembly installed.

I'm not sure why the two illustrations below were made with the expander at different heights. "BUT" if you adjust the expander too high as seen in Fig.3 the force on the downstroke of the ram will be excessive and you will damage the case neck.

My point being here you can fine tune the expander adjustment and then check the case on a runout gauge.