I have a rock chucker loading 308 FC gold fire formed ounce fired cases in my accuracy international which tack drives FC Gold medal match rounds. Here is the problem, before I resize the case the runout is virtually 0 maybe .0005 after resizing the cases the runout is between .003/.005 I have tried recentering the expander ball, oh I'm using RCBS Dies ordered a set of Reddding series A dies also and I have a redding competition seater die. What gives how can I maintain a lower runout number.

Believe it or not but I bought the Lee Collet Dies and it solved my problems. I was having the exact problem with my 35 Whelen.

First place I would look is variance in neckwall thickness. Fired cases will show the chamber profile on the outside. Run them thru a die with expander and the inside of the neck now is "trued" and any differences in wall thickness will show up on the outside of the case.
If that is not the problem then you need to start at square one. Check one thing at a time! shell holder,press ram travel, is the die in the press concentric with the the shell holder/ram ...?

muck

Your expander ball is the culprit. Try chucking expander stem in a drill and polishing the ball with 400 grit emory cloth or better yet w/crocus cloth. I put a neoprene o'ring under the lock nut for expander stem which locks the stem but allows it to seek its own center within the slack in the threads. Adjust the expander plug to the highest position possible (being sure that it is below the neck sizing portion of die), if possible so that the expander ball has started into the case neck while case neck still supported by die body to insure that it starts as straight as possible.

Another important factor is to clean case necks and lubricate. Imperial neck lube or powdered graphite works well.

Regards,
hm

Like TXPO, I solved my runout problems when I started using the Lee Collet neck die. Before that I was using the Redding S bushing dies (with and without the expander), but couldn't get the results I wanted. I've been real happy with the Lee dies, although I must add that the internal workings might need to be polished with some super fine sandpaper to remove burrs and tooling marks left over from the machining process. It's a simple process, however, and after it's done these dies really work well, without any case lube I might add.

Pull the expander stem and resize a few brass without it and check the runnout. If it's still bad you either have a bad die or a bad press. (just my opinion). possible also a bad shellholder?? Try to eliminate some variables--try a different shellholder---maybe take that set of dies to a friends house and try them in his press??

IF THE RUNNOUT DOES wind up being good without the expander ball you would then need to do some tuning of the expander ball/stem.

Muck is right on.

If your neck wall thickness varies .003" for instance, then if you run a perfectly round, perfectly lubed, perfectly "floated", expander ball through it, the interior runout of the case neck neck will be 0.0", but the exterior runout will still be .003".

It is not too unusual for case neck wall thicknesses to vary .005" from one side of the neck to the other in some makes.

Just as an experiment, outside neck turn one piece of your brass just enough to clean it up all the way around. Then run it through your normal sizing and loading process and measure the runout of the completed round.

If that reduces your runout to desired levels, then you know what to do with the rest of your brass.

If it doesn't, then you can go through all the rigamarole of floating sizer dies, floating shell-holders, trying bushing-type dies with no expander ball, etc.

AC

[ 04-16-2003, 21:11: Message edited by: Alberta Canuck ]

I ditched the expander ball and replaced with the collar the holds the decapping rod, pulled it up as high as possible, and left a gap between the ram and the die body, used imperial die wax, and that gets it down to .001". Occasionaly one will jump out to .002" or even .0025", but the sierra MK's pull it back down. I beleive that is due to not having turned the necks, and it is Lapua brass. So not even Lapua is immune to out-of-size neck thickness.