
11-02-2009, 06:51 PM
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Join Date: Jan 2005
Location: Hilliard, Ohio
Posts: 9,997
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The shorter cut is designed to meter more easily, but longer grains are easier to get consistent ignition from. Hatcher wrote about working up a load for National Match ammunition one year (back when the military still supplied the ammo for matches) in which he had two powders very similar to what is now IMR4320. One had grains 1/22" long and the other had longer 1/11" grains. The former would meter within an extreme spread of 0.6 grains in the arsenal loading machines, while the latter was much more difficult for it, producing an extreme spread of 1.7 grains; a big number by a modern reloader's standards. Yet, in machine rest testing, the sloppier load of the coarser grained powder was consistently more accurate.
Hatcher believed easier passage of the flame front through the coarser grains was responsible for achieving ignition enough better to overwhelm the better consistency of the finer grain loads. He also said that new records were set at the nationals with that coarse grained ammunition. He reported that some know-it-all pulled some bullets an pronounced it inferior because the charge variation was higher than the ammunition issued the year before. The records somehow escaped this fellow's notice.
The bottom line is that until you work up loads with both, you won't know which version might do better in your gun, or if you will see any difference at all? If you are lucky enough to find a charge weight-indifferent load as Hatcher did, you won't really care about the metering precision much. At that point, you can just get one of the inexpensive Lee Perfect measures to use with it, which will do about as well as any with coarse sticks. The only measure I know of that does better with them is the JDS Quick Measure. It's design can't cut grains, and my copy is never off by more than .2 grains. More usually the error is half that. But it costs more than the Lee.
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Nick
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