Setting up a RCBS Die

[jsthntn247]

I have a 35 whelen that I shoot during Mississippi's "primitive weapons" season. I want to set the die up for minimal shoulder bump .002. I have it set up right now where it is a nickel's thickness from the shell holder so that it doesn't crimp the cartridge. The decapper is about 3/8" past the bottom of the die. The best I can tell with calipers I am bumping the shoulder's back .004. Question is do I screw the whole decapper assembly down further or back deeper into the die to get less shoulder bump? This is a single shot so I'm not worried about feeding issues. It is also stretching the brass .010 right now when resized, is this normal??

 

[Waskawood]

Wouldn't you screw the die out of the press a tad? The decapper assembly doesn't move the shoulder.

 

[PREMOD70]

You have a whole lot of measurements going on, how are you using the calipers to get the various measurements? Are you also using a RCBS shellholder?

 

[jsthntn247]

Using a Lee universal shell holder

 

[BoydAllen]

You have several problems as far as understanding how your die works. First of all, it is your seater die that would crimp, not your FL die. I highly doubt that you are getting any shoulder bump with the bottom of your FL die a nickel's thickness off of the shell holder. Second, as was stated in an earlier reply, moving the decapping assembly has no effect on shoulder bump. It needs to be just far enough down in the die to reliably decap. If you end up lowering the die a bunch to get it down to where it will touch the shoulder, I would raise the decapping assembly by the same amount, so that your expander does not run into the bottom of the case and bend the rod. Thirdly, as was asked before, just exactly how are you measuring shoulder bump, with what tools, and technique? The reason that I ask is that if you think that your are bumping shoulders with the die backed off that far, I would guess that your bump measurement technique may not be correct. Lastly, I am not aware of a Lee universal shell holder that is used for sizing or seating on a press. Perhaps you could give us a link to a picture or listing.

 

[K22]

The best method I've found for setting up a full size die for proper sizing is using a Wilson Case Gage. The gage as two steps which will tell you if you have the proper head space. By adjusting the die so that the case is approximately half way between the steps you can prevent over sizing but sizing enough to permit easy chambering to enhance accuracy. This works so well for me that I no longer neck size my cases.

Sinclair International sells a specific tool to measure shoulder bump if you feel you need to do that but I've found that using the Wilson Case Gauge to set up my dies produces very accurate reloads that are problem free with regards to chambering.