sizing_die_setup_group.jpg

Thread the sizing die down to contact the shellholder when the press ram is at its full height. The author does not recommend ever setting a press to “cam-over” because it’s just not necessary. If your press cams, screw the die down until it hits the shellholder at the highest point of travel in the press ram. Then back the die off (up) one full turn. Lightly seat the die body lock ring against the press top, and commence and continue the following process: lube and size the case, check the headspace; adjust the die downward, check the headspace. For a 7/8-14 thread, which is virtually all presses, a full turn equals 0.0174 inches, and an 1/8 turn is about 0.009. That little bit of knowledge helps keep from going too far too soon, and also shows just how fine the adjustments get right at the end. When you think you got it, size a few more cases and read them. When you know you got it, lock the die ring. The author makes an index mark for security, and then installs and removes the die holding only the lock ring, not the die body. Note: the expander/decapping assembly was removed from this die just to point out that it’s not necessary to establish the sizing amount.

8 thoughts on “sizing_die_setup_group.jpg”

  1. There is a typo.
    For a 7/8-14 thread, which is virtually all presses, a full turn equals 0.0714 inches, NOT 0.0174 inches.

  2. I’m old and my math must therefore have deteriorated like the rest of me, but how does 0.009 times 8 = .0174, or alternatively, .0174 divided by 8 = .009?
    My “old math” tells me .0174/8=.0022 or .009*8=.072.
    Inquiring minds want to know!
    Arithmetically Yours,
    bw

  3. I’m curious – and am not a mathematician, but if the standard 7/8 x 14 thread will move .0174 inches in one full turn, then I would think that in an 1/8th turn the die will move .002175 of an inch instead of the .009 stated in your article. I’m not trying to be nit-picky about this but I need to make sure I understand what you are saying. I did enjoy the article and got some good points out of it.

  4. There is a typographical error in the numbers: 1/14 = 0.0714 (instead of 0.0174) inch per turn of the die. The 1/8-turn is correct at 0.009″.

    I have read & practice just about all of Glen Zedikers articles & books. I trust his knowledge + experience = wisdom for shooting hardware, technique, reloading, etc. He bases much of what he writes on measurable data, working with other experts in the field, as well as extensive research, experimentation, & common sense.

  5. You guys should read the comments. I posted the “correction” as the first comment about this article. At least you can do the math.

  6. Glen, Thanks for the article.
    By this procedure, the die “floats” and there is no bottoming out to define the stopping point. I understand that if most dies bottom out against a standard shell holder, then the brass will be too short, and I understand why that is bad. In the past, I’ve loaded my match ammo (6.5cm) by allowing the die to float and bumping between .001″ and .002″ (bolt gun).
    My question is, how does “floating” the die compare with using a +.002/4/6/8/10″ shell holders, and allowing the die to bottom (gently) on the shellholder?
    One reason I’m asking is because the lock ring does not seem to give me consistent headspace from installation to installation. Each time I install the FL sizer, I waste several pieces of good brass, and lots of time, re-setting the headspace. By letting the die bottom out on the same +0.004″ Redding shell holder, I get the same number every time, and there is essentially not set-up time.
    I also SUSPECT (but have never tested) the case to case variability would be better bottoming (GENTLY) on the die. This would be because press flex does not affect the headspace measurement when the die is bottoming out (but when it’s not bottoming out, press flex could easily change the “gap” between the die and the shellholder at max travel).
    Thoughts?

  7. Scott – The die is secured to the press by the lock ring, regardless of the positional relationship between the top of the shellholder & the bottom of the die. The important thing is proper & consistent headspace from the sizing process. Any headspace variation may come from loose dies and/or lockrings or perhaps worn, out-of-round pivot pins on the ram mechanism. More on this in a bit.
    The die/lockring must set to each other and be snugly torqued (by hand) into the press. As Mr. Zediker recommends, start with the die away from the shell holder, and turn it down incrementally (adjusting & torquing the die with the lockring set at each adjustment) until the desired headspace is obtained. If all is well, the sizing/headspace should remain consistent. The key is keeping the die/lockring snug in the press.
    Now, camming the ram/shell holder against the die bottom adds undue stress to the pivot pins on the ram mechanism. Remember that the five pivot points (i.e. on an RCBS Rockchucker press) are cycled thousands of times under the compression of each stroke. The heaviest compression comes with the resizing process, and doubles/triples if a progressive press is used, many times more if the ram cams over against the die. Like all mechanical moving parts, these pivot pins & their opposing surfaces wear, and must be periodically cleaned & lubed to minimize that wear. There are a also lot of abrasive residues from the reloading processes, including burned & unburned powder, primer residue (which usually goes directly down the ram when the cases are decapped), dust, & other contaminates, that can & do accelerate wear.
    Just remember to set your dies with the use of the lockring. Set the lockring at your optimal settings (for all the dies), and snug the dies into the press before each process.
    I hope this helps clarifies things more for you.

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