case at each resizing increment). And, this test proved that when the shell- holder does not abut the resizing die, functional headspace variation is signifi- cantly increased – in this instance, mea- sured variation is 4-thousandths-inch when the shellholder almost touches the die, compared to 1½-thousandths-inch when the shellholder abuts the die. COMPETITION SHELLHOLDER LIMITATIONS
Redding does not stock these shellholders in every rim size that any given varmint hunting handloader might need. In some instances, getting a set would require placing a special order. However, upon request, Red- ding will add such a set to the process the next time it produces Competitions Shellholder sets, so the delay should not be too onerous. The other thing that some readers likely will think of is: “What if I want to get closer than the nearest too-short case headspace within 2/1000-inch? Well, that might be a good question but producing these special shellholders is expensive and a set of nine instead of a set of five might be too much for the av- erage budget. We have two alternatives. We can either special order a specific (odd-thousandths) shellholder and wait, or we simply can do a bit of judicious material removal on the next-too-tall Competitions Shellholder. Removing about 1/1000-inch does not take too long using a progression of corundum-paper grit sizes – from about 100 to about 400. I would measure initial shellholder height, then sand for a few
seconds using a sanding block, then measure again. When this sanding had removed about half the needed amount of material, as evidenced by new shell- holder height being less than original height by half the desired change, I would test shellholder for squareness. I would apply a light coating of
Prussian blue to the end of a quality die and install that in the press. Then I would raise the ram to allow the shell- holder to lightly touch the die. If a high side exists, the bluing will transfer there and there only. I would carefully sand that side to remove the bluing. I would reapply a light coating to the die and repeat the test. I would continue this by careful steps until the shellholder touched everywhere with only a tiny amount of pressure. Then I would switch to progres-
sively finer grits and sand just enough with each to remove most of the scratch- es from the previous grit. By the time I reached 400-grit, I would expect total material removal to be about twice the removal with the coarsest grit. I would be very careful to approach this with enough caution as to not remove too much material! If I then discovered that I had to remove more steel, doing so would be easy enough to accomplish. Meanwhile, the closest 2/1000-
inch is probably close enough for most of us most of the time. It certainly is far superior to the typical 6/1000-inch headspace generated by a conventional shellholder with most dies for cases used in most guns.
And, because the case body at TEST #3
BODY LENGTH (+/- 1/1000-INCH VARIATION FROM AVERAGE RESIZED LENGTH) DIE TOUCHING UNSIZED CASE PLUS TURNS (1/14-INCH PER TURN)
CASE 1
2 3 4 5 6 7 8 9
AS FIRED +7¹⁄₂
+9
+8¹⁄₂ +8
+9¹⁄₂ +9¹⁄₂
+10¹⁄₂ +10
0 3
Page 140 Winter 2013
+1 +2 +3 +4 +5 +6 +9¹⁄₂
+8¹⁄₂
+11¹⁄₂ +9¹⁄₂ +8¹⁄₂ +9¹⁄₂ +8¹⁄₂
10 +8 +8
+8¹⁄₂ +9
+8¹⁄₂
+9¹⁄₂ +8¹⁄₂ +9¹⁄₂
+11¹⁄₂ +9¹⁄₂
+10¹⁄₂ +9¹⁄₂
+9¹⁄₂ +10 +11¹⁄₂ +8¹⁄₂
+11
+8¹⁄₂ +8 +9¹⁄₂ +9¹⁄₂
+10 +8¹⁄₂
+9¹⁄₂ +10 +10¹⁄₂ +9¹⁄₂ +10 +10¹⁄₂ +10¹⁄₂ +10 +9
+11¹⁄₂
+11¹⁄₂ +12
+10¹⁄₂ +10¹⁄₂ +10¹⁄₂ +11¹⁄₂ +11¹⁄₂ +11¹⁄₂ +11 +12
+11¹⁄₂ +12
+7
+10¹⁄₂ +10¹⁄₂ +11
+11¹⁄₂ +11
+12¹⁄₂ +13¹⁄₂ +11¹⁄₂ +12
+12¹⁄₂
AVERAGE CHANGE FROM AS-FIRED CONDITION (1/1000-INCH) +0.20 +0.10 +0.95 +1.85 +2.30 +2.70 MAXIMUM CASE-TO-CASE VARIATION (1/1000-INCH) 1¹⁄₂
3¹⁄₂ 3 2¹⁄₂ 1¹⁄₂ 2¹⁄₂
+12¹⁄₂ +12 +11 +13
+12 ¹⁄₂ +13¹⁄₂ +15
+14¹⁄₂ +15
+14¹⁄₂
+4.70 4
ABUTTING -¹⁄₂
0 0 0
-1
-¹⁄₂ -¹⁄₂
+¹⁄₂ 0
-1
-9¹⁄₅ 1¹⁄₂
the transition from the hollow section to the head has some ability to stretch elastically, functional headspace of about 2/1000-inch is not apt to result in much, if any, permanent case stretching in most cases when used in most guns. To accomplish functional head-
space reductions with the Co-Ax press, I have been pestering my friends at For- ster Products to offer a precision set of shims that a discriminating handloader could install, as needed, under the jaw plates of that superior press. With a set of six such shims (1, 1½, 2, 4, 8, and 16), a handloader could achieve headspace reduction adjustments in half-thou- sandths increments from 1 to 32½ (with misses only at ½ and 32). This would seem to represent adequate precision and adjustment for practically any need. When this happens, my Co-Ax will go back in place as my primary single-stage press. I suppose that if enough Co-Ax owners made the same request this might happen. Meanwhile, Co-Ax own- ers easily can use Redding Competition shellholders with that press simply by installing the conventional shell holder adaptor that Forster offers. CONCLUSION
When full-length resizing cases for typical chambers using typical dies, the only way to simultaneously minimize headspace and maximize headspace uniformity is to use the correct Redding Competition shellholder with the sizing die adjusted to solidly abut the shell- holder while resizing all cases within the batch.
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