OP Quote - The first try was with Vihtavuoi N-310 using data from their webpage.
First 1.8 gr: 517 fps, awful accuracy, and huge velocity spread. I think it was a problem with inconsistent ignition due to low pressure....

The problem is that Vihtavuori shows 2.2 gr giving 909 fps! OK they used a 7” barrel, probably not vented but I should have been less than 200 fps off. The extreme velocity spread for the last two loads was about 100 fps even though accuracy was good considering the fixed sights on a J frame.

I know it may sound a bit far-fetched but this kind of result is not that unusual when powder charges do not come all that close to filling the case volume. I have had similar results, as have others, that have posted their experiences on this forum.

I have had notable, variable, velocity results due, mostly, to powder placement in the cartridge case. Considerably more consistent results were obtained when the powder was physically closer to the base of the case (primer) accomplished by gently shaking the loaded firearm, with muzzle up, and then carefully returning to firing position. If the opposite operation is performed you may have a difficult time believing the difference in velocity and the far greater standard deviation of muzzle velocities.

My personal experience is that "coated" .32 bullets generally offer the highest muzzle velocities when all other factors are similar. I've compared identical bullets, copper-plated (washed), lubricated lead alloy, powder-coated that were otherwise loaded identically. Powder-coated almost always wins the race.

Congrats on your use of a chronograph. Hard to believe the number of fellas that reload without one and settle for guess-work.

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