Originally Posted by SidecarFlip
As long as we are discussing dies, I want to bring up a hint of sorts...
On RCBS dies, the expander ball decapping pin collet sometimes appears to be off center when you rotate the die body and observe the end of the expander ball rod. Whats occuring is the the slop in the threaded rod allows the jam nut to lock the shaft slightly offcenter. Thats easily fixed by adding a ground and case hardened flat washer between the jam nut and the top knurled knob before tightening the jam nut. The washer spreads out the locking force and allows the expander ball/shaft to center in the bore.
I too, have noticed off center decapping pins and expander balls. Someone suggested I put a decapped case in the press, lower the rod until the pin goes through the flash hole then tighten the lock ring; very tight. That fairly well centers the expander in the die.
Regarding off center expander balls, after measuring neck runout on fired cases then full length sizing them in conventional dies and checking neck runout again, the tighter the expander ball is in the sized down case neck and the more friction there is, the more the necks get bent as the ball goes up and out of them.
That can be minimized by first cleaning out the powder/primer residue in fired case mouths by running them over a spinning bore brush in an electric drill. Do this before cleaning the cases.
Another thing to do is use the next larger size expander ball then polish it down to the same diameter as the original but with a much smoother finish. I've polished down .31 caliber expander balls to diameters of .3075" to .3085" in .0005" steps to get less neck tension on 30 caliber cases. RCBS 30 caliber expander balls have typically been .3070" diameter; to me, that's too small. Case mouths deburred with traditional tools typically make a sharp edge on the inside that can scrape off a lot of bullet jacket unevenly around them and that unbalances them. I use an Easy Out turned clockwise to debure trimmed cases. Radiusing that edge with a bore brush and using larger expander balls helps a lot.
Opening up the neck in full length sizing dies or using bushing dies solves all these bent neck issues.
One can use most any die for a larger case to decap smaller cartridges in their press. Be sure to mount it high enough in the press to clear the case mouth.