Rock Chucker Bushing

[carlsbad]

If you can measure .0005" in a formed piece of brass you're better than I am.

 

[Shooter13]

It can move 1/2” and still be ok as long as it moves to the same spot every time- kinda like a sliding sleeve in a sizing die

Thanks Dusty, I'll try it again and see what it does! (when I get back on my feet!)

 

[Uncle Ed]

I am sure this has been covered somewhere here but I can't find what I am looking for. Does the steel bushing in the top of the Rock Chucker wear enough to cause neck run out during resizing? I am introducing approximately .0005" when resizing my 6 BR cases. My press is 30 years old. The dies a very sloppy fit.

If you place a rubber o-ring under the dies lock ring it allows the die to float and self center in the upper bushing in the press. I just use Lee lock rings that are finger tight on my 1973 vintage Rockchucker press with very good results.

If you use Redding competition shell holders or a standard shell holder that makes hard contact with the die will eliminate any slop in the press linkage.

The Forster Co-Ax press allows the dies to float and it shell holder system allows the case to float.

The Speer #9 reloading manual tells you to not lock the die down until you have a lubed sized case in the die with the ram at full extension and then tighten the lock ring. This procedure centers the die in the press threads and concentric with the shell holder.

Bottom line, if some slop and movement is good for the Co-Ax press it is also helpful for your Rockchucker press.

O-Rings on Dies May Reduce Run-Out
https://www.accurateshooter.com/technical-articles/reloading/o-rings-on-dies-may-reduce-run-out/

Fourteen Reloading Presses Compared: Single-Stage Shootout
https://ultimatereloader.com/2019/04/08/fourteen-reloading-presses-compared-single-stage-shootout/

Summary Data: Precision and Evaluation Metrics
Orange = Bottom Score, Green = Top Score

 

[Old Navy]

Five ten thousandths? .0005 (1/2 of one thousandth)

Or...0.005 Five thousandths??

 

[Old Navy]

I have a gauge similar to Sinclair's concentricity gauge. Fired cases have approximately .0005" runout. (inside a .001 mark on the dial) After they are sized they are over the .001" mark on the dial. I know this is splitting hairs but that is what we do here on this forum.