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Old 01-21-2010, 09:20 AM
.Steve. .Steve. is offline
 
Join Date: Oct 2009
Posts: 834
Default Powder Measures, WW296, Old Cases' Length

The following was added to the sticky at the top of the page and put here to save the bother of reading the whole thing to find this.

WW296 and Powder Measures

WW296 is a very fine grain ball powder. It seems to flow quite well in most powder measures. Seems is the operative idea. WW296 and H110 cannot safely be reduced beyond 3% at most according to the manufacturer. Before trusting any measure to charge a case directly, it should be tested against a scale extensively.

Redding BR-30 (range 10-50 grains) and Redding 10X Competition (range 1-25 grains) meter WW296 with an observed 0.1 +/- grain variation. The 10X is probably the most accurate small charge measure made.

A RCBS Little Dandy using rotor #16 with about 10 drops of dried nylon fingernail polish in the bottom of the drilled fixed cavity to reduce the capacity is equally as accurate throwing charges just under 15.0 grains. All three of these systems use the idea of a round tube filled and emptied by rotation.

A Lyman #55, grey color, turned out to be useless for WW296. The Lyman #55 system uses sliders that move left and right creating a square shouldered hole in a cylinder. The sliders can be lined up for a straight edge or offset slightly making a stepped cavity. They should never be adjusted so that the top slider partially covers over the larger slider hole underneath.

Careful testing has observed that using WW296 with a Lyman #55 creates a safety problem. The measure throws short charges. WW296 cannot safely be reduced beyond 3%. The error range of the Lyman #55 approaches 20% short charges.

A Lyman #55 was set up very carefully to throw 14.5 grains of WW296 measuring individual charges. Three sets of 10 charges weighing 145.3, .4, and .3 grains were thrown. All seemed to work well. Loading cases, short charges were noticed. Weighing everyone, the pattern ran with charges fairly consistently near 14.5, but sometimes like this: 14.5, 14.0, 14.2, 14.5, 14.0, 12.5.

Every effort was made to be consistent. The measure does not throw WW296 consistently. With the Lyman #55, it was not a full versus empty hopper problem, but two adjacent charges being very different.

It is clearly impossible for the charge to increase past 14.5. The measure is capable of short charging. A guess is it bridges somewhere in the hopper and rotor interface and does not fill the rotor cavity completely. It seems to either fill it fairly well, or lose 3 grains somehow. A Lyman #55 Powder measure should not be used for any fine grain powder like WW296 or H110.

Based on past experience, having one orange one and one grey one, they would not hold a consistent charge over a period of time. The sliders always seemed to be walking no matter how tight the thumbscrews were set.

The Redding BR series never change unless you change them. They are consistent with WW296 within 0.1 +/- grain in a 15.0 charge for an average. They can also be reset fairly easily with the micrometer system. The Lymans use three slides and there is no hope of resetting them without starting all over again.



Case Length

Case length in the carbine case matters for reasons of headspace, ignition, and extraction. Too long causes bolt closing problems and too short increases headspace, makes it hard for the firing pin to reach the primer, and in the extreme makes it hard for the extractor to pop over the case rim. Using a batch of old many times reloaded cases, an oddity was observed. The cases had been full length resized, expanded, and then trimmed each reloading to be in the 1.280-1.282” range. They were never cut short.

With this batch of cases, the fired cases measured in the 1.270” area. Full length resizing them did not make them much longer. The FLR and expanded cases hovered in the 1.278”area which is a little short. They were loaded and fired without problems. Much shorter than this area would have resulted in the case being too short to be easily forced under the extractor. It was also observed that the brass was stiff and did not spring back after being fired, work hardening, as it were, from repeated reloadings.
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