RCBS dies and run out

[yodave]

I run an older RCBS rock chucker press, you know one of the last good ones before they went offshore.......

I find that some seating and sizing dies give me more run out then others, and not always the same amount of run out from one loading to the other, it finally hit me that the threads between the press and the dies all seam to be a bit sloppy..........so after some head scratching and playing around I got my run out down to an acceptable level......but how you ask........well a couple of wraps of Teflon tape on the dies seamed to help center up the dies in the press a lot better and removed a lot of that run out that was evident using everything as per the instructions..........


okay now share a tip or two........

 

[Varmit]

Thanks, I will try that and see if they improve

 

[sharp shooter]

I hate run out……..I leave my dies and de-capping pins a bit loose so they somewhat centre themselves. A VLD chamfer helps and I am slowiy obtaining RCBS competition dies to make seating easier. And I switched to Lapua brass many moons ago and saw a difference right away. Next purchase to help avoid runout will be a Wilson trimmer.

 

[Chinbullco]

Need to find where run out is occuring before "fixing". If firing the cartridge creates run out brass is thin one side and nothing will fix. If resizing die creates run out loosen lock ring on die and remove shell holder snap ring allowing die and shell holder to "float". Set de-capping / neck expander rod under downward tension. If seating die is run out culprit make sure bullet seating cup is locked in straight and bullet tips don't bottom in bullet seater cup. If the trimmed case mouth shows run out buy yourself a Wilson case trimmer.

 

[bigedp51]

A older method of centering your dies in the press threads was to leave the dies lock ring loose and resize a lubed case. When the ram was at the top of its stroke with the lubed case in the shell holder "then" the dies lock ring would be tightened. And the die would be centered in the press. (hopefully)

Plus the fact that more neck runout is caused by locking down the expander button and spindle off center than any other reason.

Simple solutions today.

Below on the left is the RCBS expander and spindle assembly and on the right is a Forster unit. The Forster unit has a thick rubber washer/grommet under the lock nut, this allows the spindle to float and self center in the neck of the case. The expander button is also located high on the spindle and the expander enters the case neck while the neck of the case is still centered in the neck of the die. Meaning the expander button will not pull you case necks off center and reduce your neck runout.

Below the Forster expander and spindle unit that can be ordered separately fitted to a RCBS .223 die. "AND" the RCBS die has also been fitted with a Lee die lockring with a rubber o-ring fitted to the bottom of the lockring.

The die is only tightened down finger tight and a reference mark is placed on the die lock ring and press, this allows the die to float and self center in the threads of the press. The expander floats and self centers inside the die and the end result is more concentric ammo. By doing what is pictured above I have turned my 1973 Rockchucker press into a Forster Coaxal press that allows the dies to float in the press for a lot less than $300.00
And after over 46 years of reloading I'm now producing cases with the "least" amount of neck runout when full length resizing..


Forster Full Length Sizing Die Cutaway
https://www.youtube.com/watch?v=V2Wt8-VqeAE