Advice on misaligned RC IV

[clannagael]

Hi,

I need some advice on my Rockchucker IV. I've been seeing a lot of runout in my loads so I've been trying to track it down. I think I may have found the culprit - the ram seems to be misaligned. I'd like to know if anyone else has seen this (is it normal)? Is there any way to fix it? Is this even the problem? Advice?

As you can see when I raise the ram the first contact point is the front edge of the cartridge case. It happens with all of my dies and two different shellholders, an RCBS and a Hornady.




Thanks.

 

[JRS]

The Rockchucker, like most mass produced presses are bored in two separate steps. They aren't aligned very well. The Lee Classic Cast is bored in one step. I haven't used my Rockchucker for a number of years. I use two classic cast presses, along with my Crawford (Hood) presses.

 

[Scott Harris]

People "float" their dies and the shell holder with a rubber o-rings to help the die and brass align better. You can try this by removing the c-clamp that holds the shellholder and replace it with an o-ring to keep it in place and put an o-ring under the locking ring. This can take care of small alignment issues and improve runout. That said, your press looks really mis-aligned. I'd call RCBS.

 

[LHSmith]

People "float" their dies and the shell holder with a rubber o-rings to help the die and brass align better. You can try this by removing the c-clamp that holds the shellholder and replace it with an o-ring to keep it in place and put an o-ring under the locking ring. This can take care of small alignment issues and improve runout. That said, your press looks really mis-aligned. I'd call RCBS.

+1....I don't even use an o-ring....I let the S/H run commando.

 

[watercam]

+1 call RCBS.

 

[M-61]

Just wondering.....is this a press you have been using for some time and the problem just occurred now? Has it loaded acceptable ammo in the past?

 

[clannagael]

Just wondering.....is this a press you have been using for some time and the problem just occurred now? Has it loaded acceptable ammo in the past?

Great question.

Indeed, I've had the press for about 6 years and I've only recently noticed this problem. I started noticing more runout than usual so I checked my dies, cases, etc. Cleaned and lubed everything but then I noticed when I applied some dry lube to neck size they were coming out with an unusual pattern - the graphite ring was really light on one side. That's when I discovered the misalignment. If I rotate shell holders around 360 degrees I can find a suitable, but not necessarily acceptable point where it is more centered.

 

[fredhorace77]

People "float" their dies and the shell holder with a rubber o-rings to help the die and brass align better. You can try this by removing the c-clamp that holds the shellholder and replace it with an o-ring to keep it in place and put an o-ring under the locking ring. This can take care of small alignment issues and improve runout. That said, your press looks really mis-aligned. I'd call RCBS.

+1....I don't even use an o-ring....I let the S/H run commando.

lol, run commando, u had me cracking up. Reminded me of an episode of Seinfeld. ..

 

[bigedp51]

The O-Ring for the shell holder is a 7/8 OD x 11/16 ID x 3/32.

Even Commandos secure their weapons to keep from loosing them.

 

[Patch700]

A couple things to try... First remove circlip that retains shell holder as mentioned. And secondly , have you tried rotating the shell holder 90 or 180 degrees after the cartridge has been inserted to ensure that the shell holder itself has not been ground off center...

A friend of mine had issues much like yours and when i asked what happened if he rotated the shell holder he said " it does it with another shell holder so that cant be it".

Turns out they were both somewhat tight fitting to the cartridge rim AND. Somewhat off center.. I elongated the opening of the ram a small amount to allow the shell holder to find center once brass went up into die , problem solved.

 

[clannagael]

I set up a dial indicator tonight and took some different measurements.

Interestingly the ram has less than .001 runout for the whole stroke. It's very precise and has no play.

On the other hand I measured the two shellholders - an RCBS #3 and a Hornady #1.

Hornady: .001+ runout on the face. < .001 on the collar
RCBS: .006+ runout on the face. >001 on the collar

I'm going to play around with the shellholders and "floating" them to see if I can get some more insight.

Thanks for the feedback.

 

[Dusty Stevens]

Remember- your die is where runout stems from but only as long as your press isnt forcing the issue. All a press needs to do is push a case into the die and extract it. Loose as it can be and still pull a case is the best bet. Make it loose everywhere you can

 

[chapstix97]

I don't use the O ring, I lightly finger tighten die down until touches the press.

 

[bigedp51]

I don't use the O ring, I lightly finger tighten die down until touches the press.

We are talking about using a O-ring to hold the shell holder in the ram and letting the shell holder "float". And not about O-rings under the dies lock ring. :

Evelyn Wood
Reading Dynamics
http://www.ewrd.com/ewrd/index.asp

 

[JRS]

I don't use the O ring, I lightly finger tighten die down until touches the press.

We are talking about using a O-ring to hold the shell holder in the ram and letting the shell holder "float". And not about O-rings under the dies lock ring. :

Evelyn Wood
Reading Dynamics
http://www.ewrd.com/ewrd/index.asp

;D