Yeah, but a too-obvious bias. Like a lot of people on our site, Al prefers the time of our founders -- you know, outhouses, the left hand, a bucket of water....
I kept reading about the precision shoulder bump. I spent hours and hours, and most of the bad words I learned from my drill sargent in basic training, and there was essentially no way I could get a consistant 0.001" or 0.002" shoulder bump. Brass acted pretty much like precision machining of pink peral eraser. Heck, I couldn't even measure the shoulder bump repeatedly to that level of precision. So, taking for granted that it was important because everybody who I viewed as an expert said it was, and my .30-06 brass would stretch itself into imminant self destruction (0.005" of case thinning) in 4 uses, I took on trying to duplicate the performance of the experts.
Understand, I thought when I started that working with brass sheetmetal configured as bottleneck rifle brass to the sub mill tolerances bandied about is a myth. And I still do. And I don't think that level of precision is needed because the rifle chamber is the same every time and the brass expands to fit it before the bullet even leaves. What does matter to a guy like me making hunting ammo is controlling stretch to minimize case thinning just above the base. This is especially important on rimmed magnums or rimmed rifle cases where the shoulder has no part of the actual headspace measurement. It's complicated by the fact that the technique I was using is about as precise as precision slicing cheese.
OK, so because my .30-06 and 7mmMAG brass wasn't lasting very long I decided to figure out how to make real measurable shoulder bumps of 0.001" to 0.002" happen on a predictable basis. My first project was to figure out a reasonable way to measure this.
I started with the Hornady set with a red fixture that clamps to one jaw of the digital calipers, and their full set of inserts. They recommend applying the inserts to contact the case about halfway between the shoulder/case and shoulder/neck intersections. I worked with that for a long time but found that I could resize and measure the same case and get a different reading. I finally figured out that the expander button had a huge effect on the shoulder where the tool was making it's measurement. I determined that the actual shoulder wasn't moving from die trip to die trip, but the button drag changed it where I was measuring and so did it's distortion of the brass.
So I designed a set of substitute collars to use in the tool. Outside shape was the same, but I made up a table of dimensions for the small hole, the larger hole, and the angle where the collar would touch the brass. I dimensioned it so the contact point would occur pretty much on a band 20 to 30 mills wide right at the shoulder with a collar surface cut to the SAAMI angle (to the acccuracy of my compound angle measurements). Table and sketch in hand, I went to the shop, oiled up the old 9" South Bend, stuck a piece of 3/4" aluminum rod through the spindle and machined a new set of collars. [I love that old lathe, it's quiet, accurate, repeats really well, has accurate lead screws, and I've been using it since I was 8 years old (62 years I've used it) - so the fun and relaxation were a bonus.]
Armed with the new collars which made much more reliable measurements of the parameter of interest than the originals, I took on the adjustment of the die itself. I tried shims under the die lock ring to adjust the gap between the shell holder and the base of the die which intern adjusted the shoulder bump. Well, after hours and hours, and uttering every bad word I know, and some new ones I made up on the spot, I was nowhere. Remove the die, replace it, and go thorugh the whole process all over again. I even tried schemes for torquing the dies into the press using a deep socket on the lock ring (a Redding Boss press, if it matters). No success at getting the results I heard being bandied about on the web by those that had the "right stuff".
I finally concluded that I was missing something or those guys with the right stuff were just plain BSing all of us because I could "not" duplicate their results. I hadn't tried a custom die but with the tools I had, it was not happening. Period.
Then I read about the Redding competition shell holders. Once I figured out how they worked, varying the thickness of the rim to bring the base to shoulder distance under the control of a hard mechanical interferernce that left the press mechanism and even die tightness in the press, out of the equation, I figure that might be the way to go. So I bought a set for the Redding size 1 shell holder and by golly, suddenly I had "the right stuff" for my .243, .22-250, and .30-06. They worked great. Most of the time I get a repeatable +/- 0.001" bump using the #4 shell holder (0.004" thicker rim). I have a Lyman 7mmMAG die that won't work no matter what, it over bumps the shoulder by seven mills even with the #10 holder in place, so I round filed it, but any other die i can set up to size to a reliable shoulder bump with no problem.
The only bottle neck rifle cartridge I don't use them on is the .22 Hornet because the brass is so thin it wouldn't matter - it would make cheese slicing look like ultimate precision. I just neck size them and don't worry about it, and they always chamber in my CZ Hornet - isn't broke so I'm not fixing it. The actual measured rim thickness headspace on the CZ is about 0.001" as close as I can measure it based on primer protrusion below the base when primed empty brass with no bullet is fired in the chamber).
I've found the competition shell holders combined with the full contact holder/die base interface is a whole bunch faster to adjust for an ~zero to 0.002" shoulder bump than any other method I've tried. Nobody not bumping the shell holder into the base of the die should fool themselves into thinking including their press linkage and ram fit into the sizing process has anything like the same repeatability as the holder/die pressed together. What I get out of bumping them together, as near as I can measure it, is repeatability within a mill or a bit less. Better than I expected when I started. Pretty good for working the the metalic equivelant of rubber.
Al, you and I can agree to disagree right now and save a lot of typing. You will never change my mind and convince me that having the linkage in the loop improves the accuracy or repeatability of the process. And I realize from reading your post above that I'll never convince you that taking it out of the loop will improve the accuracy or repeatability of the process, so I won't try.
Fitch