bigted said:
black and pyrodex style powders are meassured by volume only. never meassure your charge by a scale for weight. only use a powder meassure that is adjustable to start with and later when you get a load that will stay with the rifle...you may want to make a powder meassure for that rifle outta horn or a piece of brass or some such thing.
but never depend on a scale to come up with a weighed charge for your black powder gun...any of them :surrender:
With respect, that is a common misconception, but I've never understood where it came from. B.P. charges have always been been specified by weight, whether in pounds, ounces, drams, or grains. FWIW, there is no volumetric unit of "grains". We often use the convenience of volumetric measurement to approximate a particular weight of powder, whether GOEX FFFg with my brass Treso or H4895 with my Lyman 55. Volumetric B.P. powder measures take advantage of two factors.
One factor is that, since the second quarter of the 19th century, almost all varieties of real corned "Gunpowder" have approximately the same bulk density - which is coincidentally close to that of water at 1.0g/cc. This is in sharp contrast to more modern propellants that vary drastically in bulk density. Grain size (Fg, FFFg, etc.) per se does not make a major difference - just the density, rounding, and size
distribution of the powder grains. Whatever the volume is in cubic inches or cubic centimeters, the "100gr" setting on a powder measure
should throw charges weighing
approximately 100gr of any real black powder. This will naturally vary somewhat with both the density of the powder and the technique of measurement - as-poured, or tapped to settle then topped up and/or struck-off level. My reading suggests that, in the old days, manufacturers often calibrated measures for a particular powder and a particular technique - often tapped and struck-off. Sometimes it seems to have been for more of an average density of different granulations and/or manufacturers, and nowadays, some seem to be set for the density of water as an approximation. Unfortunately, this calibration seems to be inconsistently done now, as some measures of recent manufacture are way off with any powder - but this is consistent with all powders in those measures, and is a design & manufacturing problem, not something inherent to the "system".
The other factor is that real B.P. is not particularly sensitive to small variations in charges. Hence, the somewhat greater variations in individual charges is less important for accuracy, except possibly in the higher levels of target shooting, where shooters often weigh all charges. The difference in power among different powders, lots, and granulations is dealt with separately from the measurement of the powder, as it is also with modern powders. One shooter might note that she gets about the same trajectory and POI with 60gr of GOEX FFFg, 85gr of GOEX FFg, or 95gr of '98 vintage Elephant FFg, but not note which lots or how these charges were measured, and this information is often good enough for our purposes. In contrast, a long-range competition shooter might note that that he has to adjust his charges, weighed to .1gr, by up to 3 grains when changing between lots of post-2004 Goex Fg.
It is when we get into the B.P. substitutes that the measurement technique
must be specified. The new powders are often formulated and manufactured to have the same volume as the equivalent B.P. charge, and thus for the use of the same measured volume as that weight of B.P., while being of significantly lower weight. Hence, if weighed charges are used, a conversion like that posted by Christian becomes imperative.
Regards,
Joel
