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View Full Version : Oddball X-Die, should I return it to RCBS?



stubbicatt
04-14-2013, 07:07 AM
As I understand it, RCBS dies are cut with chamber reamers just like the ones used in chambering a rifle.

I bought a RCBS 243 Winchester "X-Die," a design I have really come to appreciate over the years in 308 and 223. So extending it to 243 seemed reasonable.

Following the instructions, one sets the "outside" dimensions of the case first, then the neck length portion of the die. By this I mean, I back off the neck length shoulder/mandrel and set up the die for proper dimensions by screwing it into the press until it contacts the shellholder, and then maybe 1/4 turn further to get proper FL sizing.

Over the years I have learned by experience that often one needs to back off the die from contact with the shell holder a little bit to arrive at the smallest amount of shoulder setback that allows easy chambering in your rifle. So, using a Stoney Point comparator setup, I was able to measure with a vernier caliper the shoulder to case head length of brass fired in my rifle to get a datum point. Starting with the die fully in contact with the shell holder, it set the shoulder back almost 2/100ths of an inch over fired length! It also set the shoulder back nearly the same amount as compared to new, unfired, factory ammunition! You can look at the brass and see an obvious difference with respect to the point on the walls of a case where the shoulder begins between these cases.

Wow. This was a surprise! Talk about asking for a case head separation!

So I analyzed what I had here. Either there is an issue with the die, or an issue with the shellholder, or an issue with the method of measuring the shoulder to casehead length, or a combination of these things. After looking closely at the setup, the angle of the shoulders of the resized cases is different from either new brass or as fired brass, the resized brass having a "steeper" angle. --So this is definitely the die. If the angle is different, then the datum point on the shoulder where the headspace dimension is measured will have changed, leading to wonky measurements.

I'm pretty sure the die was cut with a reject reamer or something.

Can anybody offer a different analysis before I send it back to RCBS? I mean they have NEVER sold me a die that wasn't perfect, dimension wise.

Thanks in advance.

Schuetzenman
04-14-2013, 07:48 AM
.02" set back, not .002"? If so something is definitely wrong. Shell holder isn't any kind of cause of that. Can you post a photo of the resized case and a virgin case or fired case? It almost sounds like you're describing what you might get from an Ackley Improved die.

stubbicatt
04-15-2013, 06:16 AM
.02" set back, not .002"? If so something is definitely wrong. Shell holder isn't any kind of cause of that. Can you post a photo of the resized case and a virgin case or fired case? It almost sounds like you're describing what you might get from an Ackley Improved die.

Yes, 2 100ths of an inch. And I think I describe the shoulder angle incorrectly, it is not like an Ackley Improved shoulder, but sharper, more tapered when pulled from the die. One thing I didn't do was to disassemble the die and clean it of preservative etc. I don't think that it is possible to put that much cosmoline like substance in a die, but I will clean it with a chamber brush before proceeding to the next step.

deth502
04-15-2013, 03:37 PM
my first thought would as well be some sort of "improved" die, but afaik, rcbs does not make any of those calibers in the x-series (or at least didnt a few yrs ago)

second guess would be not enough lube, ie, the die, instead of sizing the neck down, is stopping it and forcing it back into the shoulder.

deth502
04-15-2013, 03:38 PM
or, some machining marks in the die, or burrs, or foreign material could also be stopping the neck.

stubbicatt
04-15-2013, 03:44 PM
Starting over:

The overall difference in as sized versus fired brass is .01", NOT .02", as measured by the Stoney Point Comparator. My memory let me down again.

Photo 1: The fired case is on the far right, two cases sized in the X die are to the left, one with a bullet and one without. In this photo you can see that both the neck/shoulder junction and the shoulder/case body junctions are set back a visible amount. The Stoney Point Comparator indicates that this is only .01" difference. The two sized cases reflect the same dimension, as viewed with the Mod 0, Mk 1* eyeball.

http://i80.photobucket.com/albums/j187/stubbicatt/IMG_0211_zps964c654b.jpg (http://s80.photobucket.com/user/stubbicatt/media/IMG_0211_zps964c654b.jpg.html)

Photo 2: I have added to the left a 4th case, this one unfired, virgin brass. In my mind you can clearly see that the neck/shoulder junction and the shoulder/case wall junction are visibly further from the case head than they are on the resized cases to the right, and the fired case on the far right also has a "longer" dimension to the shoulder/case wall junction. The overall length of the sized cases and the virgin, unfired case to the left, are comparable. The overall length of the unsized, fired, case on the far right is shorter, as would be expected.

http://i80.photobucket.com/albums/j187/stubbicatt/IMG_0217_zpsea9405eb.jpg (http://s80.photobucket.com/user/stubbicatt/media/IMG_0217_zpsea9405eb.jpg.html)

My concern is that the only way to account for these differences is to consider that the angle of the shoulder portion of the resized case is more tapered than the as fired or virgin cases. In essence, the arbitrary datum point on the shoulder where the Comparator takes its measurement may not correctly reflect the shoulder setback, given that the resized cases have steeper shoulders.

I hope you guys can see what I'm talking about here. Of course, it could simply be a tempest in a teapot.

O.S.O.K.
04-17-2013, 03:17 PM
Call RCBS - they are great guys and will help you out. They'll probably ask you to send it in and then they'll most likely send you a new one.

Schuetzenman
04-19-2013, 06:48 PM
I would have to concure, contact RCBS. They may want to have the die and a few of the resized cases back for analysis.

stubbicatt
04-22-2013, 08:21 AM
Alright then. I will send the die back. I am unwilling to part with my Lapua brass, having paid nearly a dollar each for it. Heck, I may just buy a box of commercial Winchester and fire it in my rifle and resize the cases and send one of those cases instead.

El Laton Caliente
04-22-2013, 08:28 AM
Alright then. I will send the die back. I am unwilling to part with my Lapua brass, having paid nearly a dollar each for it. Heck, I may just buy a box of commercial Winchester and fire it in my rifle and resize the cases and send one of those cases instead.

LOL, have you tried to buy cheap .223 lately?