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.
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.