Tech Line & Tips (FAQs)
Most hunters and many other shooters seeking smooth chambering reloads, full length size their cases each time. Since the interior dimensions of sizing dies are determined by the manufacturer, adjusting the shoulder setback is the only control a reloader has over how much a fired case is sized.
In the past, sizing die adjustment has been made through the trial and error method of rotating the die body in the reloading press. While acceptable results can be obtained using this method, precise adjustments are difficult at best.
Using this method, firm contact with the shellholder was not always possible. As a result, irregularities in brass hardness and thickness, as well as the uniformity and quantity of case lube affected shoulder setback. The resulting headspace variations created can adversely affect accuracy due to non-uniform primer/powder ignition. "Squaring" the die in the press is also precluded with this method of die adjustment.
To provide desirable shellholder-to-die contact during sizing, without excessively setting the case shoulder back, Redding now offers shellholders that are in increments of .002" thicker than the industry standard. The nominal thickness for industry standard shellholders is .125". (See dimension X on the shellholder diagram.) Our new Competition Shellholder Set includes five shellholders that are thicker than this in increments of .002". Therefore, the set includes shellholders that are marked +.002, +.004, +.006, +.008 and +.010, which is the amount the shellholder will decrease case to chamber headspace.
To select the proper shellholder for your particular firearm's chamber, start with the shellholder marked +.010. The shellholder should be adjusted to make firm contact with the bottom of the sizing die during the case sizing operation. Resize a case and try it (unprimed and empty) in the chamber of your firearm. If the empty case does not chamber or chambers with difficulty, switch to the shellholder marked +.008 and repeat the process. Stop at the shellholder that allows the firearm's action to close freely. Your cases are now being sized properly to fit your chamber with a minimum amount of headspace.