Joel/Calgary
50 Cal.
- Joined
- Oct 19, 2004
- Messages
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I want to start a thread on measuring shot & powder where folks share their experience and research that the moderator(s) can edit into a reference. I've seen some of this in various places, and it would seem useful to consolidate it. Here's my info, as gleaned from reading and some testing.
Hmmm... the table spacing has been squashed. I've tried to edit to keep it adequately intelligible.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
B.P. measures presume a specific density for the powder. Many modern powder measures are calibrated for an average powder density of 1.00g/cc, but actual powder densities vary somewhat, depending on type and granulation (from the Mad Monk). In reality, the density assumed is, at best, accurate for only certain granulation(s) from certain manufacturer(s), and other powders will not weigh exactly the marked weight. Depending on the calibration of the measure, maybe no powder will give a charge of exactly that weight. For historical reference, prior to the first quarter of the 19th century, powder was generally not as dense.
Because powder grains are not perfect spheres of uniform size, the exact weight of a powder charge will also depend on how it was measured: as-poured or settled, and if settled, by how much. Additionally, there is the matter of whether the charge was left rounded or struck off level.
When I got started reloading cartridges in the early '70s, low cost & low tech was still common enough, especially for beginners, that advice was often published for it, with original sources cited sometimes going back to the 19th century. (In our current litigious society, I doubt one could publish an article on reloading with cast bullets using a hammer, a nail, a dowel, a board with a hole drilled in it, some powder scoops, and a tea cup to hold the powder). Unfortunately, the information I'm giving is all from memory, as I don't have any of this readily available.
In measuring powder with scoops (commercial like Lee, or homemade), there were four variations on technique that gave fairly consistent results; which to use depended, in part, on what precision was good enough for the user's purposes. Each of these techniques has a direct parallel in the use of a powder measure with a horn or flask. In approximate order of increasing precision, they are:
- Scoop the powder by sinking the measure upright into the powder container to well below its mouth, let it fill, and raise it straight up. This is approximately equivalent to pouring a rounded-full measure from a horn/flask.
- Fill and withdraw the measure as above, then strike the excess off level at the mouth. This was often called a "struck" measure by the old timers and often gave a somewhat more consistent but slightly lighter charge. In our context, it is, naturally, pour a rounded measure and strike it off level.
- Sink the scoop in the powder, then tap it (a consistent number of times and sharpness) to settle the powder before raising the scoop. Called a "shook" measure, it also tended to be more consistent, gave the heaviest charge of the four techniques, and, I vaguely recall, was often what commercial powder measures were calibrated for. This would be equivalent to our pouring a measure, tapping it to settle the charge, and topping it up as it settles.
- Combine the second and third in a "shook and struck" measure. Depending on the shape and size distribution of the powder grains and the dimensions of the measure, the settling _might_ be as effectively done after the measure was raised but before it was struck off level. This is most analogous to using a mechanical powder measure including the knocker, and was found to give the most consistent charges, and _usually_ somewhat heavier than the simple scooped one. It was, naturally, the slowest and fussiest of the four. This should be the most precise way to use a horn/flask and measure. Whether that increase in precision is needed for an individual's purposes is different matter. I recall some of the modern m/l writers mentioning using this technique (can't recall who - it was a while ago, and I don't have my stuff indexed) for maximum precision but not backing it up with comparative data.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
How much shot a measure will hold depends on the aggregate density of the shot - for lead (and its alloys), it's usually given as approximately 7 times denser than the powder, depending somewhat on the alloy. This is apparently the density of hexagonally-close-packed uniform spheres composed of lead alloys with bulk densities of 10.75-11.25 g/cc, depending on alloy, and is independent of shot size (IIRC, that should calculate to 6.9-7.2 g/cc, with most shot alloys in the 7.1-7.2 range). All comparisons I've seen of shot and powder in real-world measures actually come out with shot less than 7 times the weight of the powder because the shot are not perfectly packed in the measure. The dimensions of the measure STRONGLY affect how much shot actually fits in - especially with larger shot. Because of the effects of the geometry of the shot against the sides of the measure, larger shot will not pack as well as smaller, so it will weigh even less in a given measure, and the smaller the diameter of the measure, the greater will be the effects of shot size on charge weight. (I've heard this called "boundary effect" in a discussion of packing.) A shot measure is comparatively fat to minimize the boundary effects on packing and be more consistent with different sizes of shot but with some loss in precision, while a powder measure is skinny to allow more precise measurement of the much finer powder because the boundary-effect differences are much less among different granulations of powder.
Picture a layer of shot in the measure. In the middle, the shot is likely close to that perfectly ordered hexagonal packing, but around the edge, there will be places too small for a shot to fit, so there is less shot in the layer than a perfect hexagon of the same cross-section, or, alternatively, of a circle drawn over a wide perfect layer of hexagonally packed shot. The larger the cross-section of the measure compared to the size of the shot, the greater the portion of the area that will have shot in dense hexagonal packing (roughly proportional to the area of the measure, or to the diameter squared) and the smaller the portion with "missing" shot (roughly proportional to the circumference, or to the diameter [directly, not squared]). Similarly, the larger the shot, the wider the boundary region with "missing" shot for a given diameter of measure, and the lower the weight for that layer. The actual 3-dimensional geometry is more complicated, but the same principles still apply.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
To newcomers: you're often going to see the use of one measure for both powder and shot in dealings with muzzleloading smoothbores. Just remember that both numbers given refer to nominally-weight settings on a volumetric measure, but only one of the substances will have a weight close to the setting involved - the other will be around 7 times lighter or heavier.
The following are the traditional equivalencies, as cited in some writings and as found on combined shot and powder measures, usually "dippers"/scoops, with the shot size not specified but probably either #6 or #8, and measurement technique (scooped/poured/settled, level/rounded) not specified. BTW, drams are the traditional units of measure (weight) for powder charges, and an avoirdupois dram is 1/16 of an ounce or 1/256 of a pound or 27.34 grains, and the nominal precision of the powder measurements here is only the nearest 1/4dr (8gr).
Traditional Powder/Shot Volume Equivalences
2dr = 55gr 3/4oz Pb shot
2.1/4dr = 62gr 7/8oz Pb shot
2.1/2dr = 68gr 1oz Pb shot
2.3/4dr = 75gr 1.1/8oz Pb shot
3dr = 82gr 1.1/4oz Pb shot
3.1/4dr = 89gr 1.3/8oz Pb shot
3.1/2dr = 96gr 1.1/2oz Pb shot
3.3/4dr = 103gr 1.5/8oz Pb shot
4dr = 109gr 1.3/4oz Pb shot
4.1/4dr = 116gr 1.7/8oz Pb shot
4.1/2dr = 123gr 2oz Pb shot
The following are powder measure settings to measure out ounces of shot, as posted by GrayBear and anecdotally verified by others (measure dimensions, shot size, and measurement technique (level/ rounded) not specified):
POWDER MEASURE SETTINGS TO MEASURE OUT OUNCES OF BIRD SHOT
50 grain setting => 3/4 ounce of shot
60 grain setting => 7/8 ounce of shot
70 grain setting => 1 once of shot
80 grain setting => 1.1/8 ounces of shot
90 grain setting => 1.1/4 ounces of shot
100 grain setting => 1.3/8 ounces of shot
110 grain setting => 1.1/2 ounces of shot
120 grain setting => 1.5/8 ounces of shot
Note the difference: in a shot/powder scoop, a 3dr(82gr) powder setting is the same as a 1.1/4oz shot setting, while in a powder measure of 1/2 or 1/3 the diameter, you need a 90gr setting to get 1.1/4oz of shot.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Dimensions of 1oz Pb (#8?) shot in various gauges (diam. x height), in inches (from an old Hercules Powder reloading pamphlet):
10ga - .775 x .610
12ga - .729 x .690
16ga - .662 x .837
20ga - .615 x .968
28ga - .550 x 1.210
.410bore - .410 x 2.175
- - - - - - - - - - - - - - - - - - - - - - - - - - -
For shot materials other than lead, you can calculate a good first-approximation of the shot-measure setting by comparing their bulk densities to that of lead shot alloys.
Shot material densities and comparison to average lead shot alloys.
- material - density(g/cc) - %lead shot alloys
- Fe - 7.86g/cc - 70% // "steel"
- Bi-Sn - 9.69g/cc - 86% // "bismuth"
- W-Fe - 10.3g/cc - 92% // Federal "Tungsten-Iron"
- W-polymer - 10.6g/cc - 94% // Kent "Tungsten-Matrix"
- Pb-Sb-Sn - 10.0-10.75g/cc - 89-96% // ("high alloy", bullet material ranging down into very hard shot)
- W-Sn-Fe - 11.0g/cc - 99% // "Nice Shot"
- Pb-Sb - 11.1-11.25g/cc - nominal 100% // (normal shot alloys)
- Pb(pure) - 11.4g/cc - 102%
- W-Ni-Fe - 12.0g/cc - 107% // Remington "HeaviShot"
- W-Cu-Sn - 12.0g/cc - 107% // Olin "Tungsten-Bronze"
NOTE: Calculations of charge volumes need to take into account packing effects of different shot sizes and size of charge, e.g. a measure of Fe#1 has 63-67% the weight of the same measure of Pb#6 per findings below, rather than the 70% difference in the bulk material densities.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Steel shot contained in shotshell-reloader bushings calibrated for Pb#6 (from a short item in an old American Rifleman):
bushing -> Fe#1 +/- 1/16oz
1.1/2 -> 15/16oz
1.5/8 -> 1.1/16oz
1.3/4 -> 1.1/8oz
1.7/8 -> 1.3/16oz
2.1/4 -> 1.1/2oz
This was for Fe#1 shot, so a measure of smaller shot would weigh more, and larger shot would weigh less.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
As I use my shot measure (dipper), I get:
1.1/2oz Pb (measure) = a little more than 1.1/4oz Bi#4 = a little less than 1oz Fe#3
1.7/8oz Pb (measure) = a little more than 1.1/2oz Bi#4 = a little less than 1.1/4oz Fe#3
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Hmmm... the table spacing has been squashed. I've tried to edit to keep it adequately intelligible.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
B.P. measures presume a specific density for the powder. Many modern powder measures are calibrated for an average powder density of 1.00g/cc, but actual powder densities vary somewhat, depending on type and granulation (from the Mad Monk). In reality, the density assumed is, at best, accurate for only certain granulation(s) from certain manufacturer(s), and other powders will not weigh exactly the marked weight. Depending on the calibration of the measure, maybe no powder will give a charge of exactly that weight. For historical reference, prior to the first quarter of the 19th century, powder was generally not as dense.
Because powder grains are not perfect spheres of uniform size, the exact weight of a powder charge will also depend on how it was measured: as-poured or settled, and if settled, by how much. Additionally, there is the matter of whether the charge was left rounded or struck off level.
When I got started reloading cartridges in the early '70s, low cost & low tech was still common enough, especially for beginners, that advice was often published for it, with original sources cited sometimes going back to the 19th century. (In our current litigious society, I doubt one could publish an article on reloading with cast bullets using a hammer, a nail, a dowel, a board with a hole drilled in it, some powder scoops, and a tea cup to hold the powder). Unfortunately, the information I'm giving is all from memory, as I don't have any of this readily available.
In measuring powder with scoops (commercial like Lee, or homemade), there were four variations on technique that gave fairly consistent results; which to use depended, in part, on what precision was good enough for the user's purposes. Each of these techniques has a direct parallel in the use of a powder measure with a horn or flask. In approximate order of increasing precision, they are:
- Scoop the powder by sinking the measure upright into the powder container to well below its mouth, let it fill, and raise it straight up. This is approximately equivalent to pouring a rounded-full measure from a horn/flask.
- Fill and withdraw the measure as above, then strike the excess off level at the mouth. This was often called a "struck" measure by the old timers and often gave a somewhat more consistent but slightly lighter charge. In our context, it is, naturally, pour a rounded measure and strike it off level.
- Sink the scoop in the powder, then tap it (a consistent number of times and sharpness) to settle the powder before raising the scoop. Called a "shook" measure, it also tended to be more consistent, gave the heaviest charge of the four techniques, and, I vaguely recall, was often what commercial powder measures were calibrated for. This would be equivalent to our pouring a measure, tapping it to settle the charge, and topping it up as it settles.
- Combine the second and third in a "shook and struck" measure. Depending on the shape and size distribution of the powder grains and the dimensions of the measure, the settling _might_ be as effectively done after the measure was raised but before it was struck off level. This is most analogous to using a mechanical powder measure including the knocker, and was found to give the most consistent charges, and _usually_ somewhat heavier than the simple scooped one. It was, naturally, the slowest and fussiest of the four. This should be the most precise way to use a horn/flask and measure. Whether that increase in precision is needed for an individual's purposes is different matter. I recall some of the modern m/l writers mentioning using this technique (can't recall who - it was a while ago, and I don't have my stuff indexed) for maximum precision but not backing it up with comparative data.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
How much shot a measure will hold depends on the aggregate density of the shot - for lead (and its alloys), it's usually given as approximately 7 times denser than the powder, depending somewhat on the alloy. This is apparently the density of hexagonally-close-packed uniform spheres composed of lead alloys with bulk densities of 10.75-11.25 g/cc, depending on alloy, and is independent of shot size (IIRC, that should calculate to 6.9-7.2 g/cc, with most shot alloys in the 7.1-7.2 range). All comparisons I've seen of shot and powder in real-world measures actually come out with shot less than 7 times the weight of the powder because the shot are not perfectly packed in the measure. The dimensions of the measure STRONGLY affect how much shot actually fits in - especially with larger shot. Because of the effects of the geometry of the shot against the sides of the measure, larger shot will not pack as well as smaller, so it will weigh even less in a given measure, and the smaller the diameter of the measure, the greater will be the effects of shot size on charge weight. (I've heard this called "boundary effect" in a discussion of packing.) A shot measure is comparatively fat to minimize the boundary effects on packing and be more consistent with different sizes of shot but with some loss in precision, while a powder measure is skinny to allow more precise measurement of the much finer powder because the boundary-effect differences are much less among different granulations of powder.
Picture a layer of shot in the measure. In the middle, the shot is likely close to that perfectly ordered hexagonal packing, but around the edge, there will be places too small for a shot to fit, so there is less shot in the layer than a perfect hexagon of the same cross-section, or, alternatively, of a circle drawn over a wide perfect layer of hexagonally packed shot. The larger the cross-section of the measure compared to the size of the shot, the greater the portion of the area that will have shot in dense hexagonal packing (roughly proportional to the area of the measure, or to the diameter squared) and the smaller the portion with "missing" shot (roughly proportional to the circumference, or to the diameter [directly, not squared]). Similarly, the larger the shot, the wider the boundary region with "missing" shot for a given diameter of measure, and the lower the weight for that layer. The actual 3-dimensional geometry is more complicated, but the same principles still apply.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
To newcomers: you're often going to see the use of one measure for both powder and shot in dealings with muzzleloading smoothbores. Just remember that both numbers given refer to nominally-weight settings on a volumetric measure, but only one of the substances will have a weight close to the setting involved - the other will be around 7 times lighter or heavier.
The following are the traditional equivalencies, as cited in some writings and as found on combined shot and powder measures, usually "dippers"/scoops, with the shot size not specified but probably either #6 or #8, and measurement technique (scooped/poured/settled, level/rounded) not specified. BTW, drams are the traditional units of measure (weight) for powder charges, and an avoirdupois dram is 1/16 of an ounce or 1/256 of a pound or 27.34 grains, and the nominal precision of the powder measurements here is only the nearest 1/4dr (8gr).
Traditional Powder/Shot Volume Equivalences
2dr = 55gr 3/4oz Pb shot
2.1/4dr = 62gr 7/8oz Pb shot
2.1/2dr = 68gr 1oz Pb shot
2.3/4dr = 75gr 1.1/8oz Pb shot
3dr = 82gr 1.1/4oz Pb shot
3.1/4dr = 89gr 1.3/8oz Pb shot
3.1/2dr = 96gr 1.1/2oz Pb shot
3.3/4dr = 103gr 1.5/8oz Pb shot
4dr = 109gr 1.3/4oz Pb shot
4.1/4dr = 116gr 1.7/8oz Pb shot
4.1/2dr = 123gr 2oz Pb shot
The following are powder measure settings to measure out ounces of shot, as posted by GrayBear and anecdotally verified by others (measure dimensions, shot size, and measurement technique (level/ rounded) not specified):
POWDER MEASURE SETTINGS TO MEASURE OUT OUNCES OF BIRD SHOT
50 grain setting => 3/4 ounce of shot
60 grain setting => 7/8 ounce of shot
70 grain setting => 1 once of shot
80 grain setting => 1.1/8 ounces of shot
90 grain setting => 1.1/4 ounces of shot
100 grain setting => 1.3/8 ounces of shot
110 grain setting => 1.1/2 ounces of shot
120 grain setting => 1.5/8 ounces of shot
Note the difference: in a shot/powder scoop, a 3dr(82gr) powder setting is the same as a 1.1/4oz shot setting, while in a powder measure of 1/2 or 1/3 the diameter, you need a 90gr setting to get 1.1/4oz of shot.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Dimensions of 1oz Pb (#8?) shot in various gauges (diam. x height), in inches (from an old Hercules Powder reloading pamphlet):
10ga - .775 x .610
12ga - .729 x .690
16ga - .662 x .837
20ga - .615 x .968
28ga - .550 x 1.210
.410bore - .410 x 2.175
- - - - - - - - - - - - - - - - - - - - - - - - - - -
For shot materials other than lead, you can calculate a good first-approximation of the shot-measure setting by comparing their bulk densities to that of lead shot alloys.
Shot material densities and comparison to average lead shot alloys.
- material - density(g/cc) - %lead shot alloys
- Fe - 7.86g/cc - 70% // "steel"
- Bi-Sn - 9.69g/cc - 86% // "bismuth"
- W-Fe - 10.3g/cc - 92% // Federal "Tungsten-Iron"
- W-polymer - 10.6g/cc - 94% // Kent "Tungsten-Matrix"
- Pb-Sb-Sn - 10.0-10.75g/cc - 89-96% // ("high alloy", bullet material ranging down into very hard shot)
- W-Sn-Fe - 11.0g/cc - 99% // "Nice Shot"
- Pb-Sb - 11.1-11.25g/cc - nominal 100% // (normal shot alloys)
- Pb(pure) - 11.4g/cc - 102%
- W-Ni-Fe - 12.0g/cc - 107% // Remington "HeaviShot"
- W-Cu-Sn - 12.0g/cc - 107% // Olin "Tungsten-Bronze"
NOTE: Calculations of charge volumes need to take into account packing effects of different shot sizes and size of charge, e.g. a measure of Fe#1 has 63-67% the weight of the same measure of Pb#6 per findings below, rather than the 70% difference in the bulk material densities.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Steel shot contained in shotshell-reloader bushings calibrated for Pb#6 (from a short item in an old American Rifleman):
bushing -> Fe#1 +/- 1/16oz
1.1/2 -> 15/16oz
1.5/8 -> 1.1/16oz
1.3/4 -> 1.1/8oz
1.7/8 -> 1.3/16oz
2.1/4 -> 1.1/2oz
This was for Fe#1 shot, so a measure of smaller shot would weigh more, and larger shot would weigh less.
- - - - - - - - - - - - - - - - - - - - - - - - - - -
As I use my shot measure (dipper), I get:
1.1/2oz Pb (measure) = a little more than 1.1/4oz Bi#4 = a little less than 1oz Fe#3
1.7/8oz Pb (measure) = a little more than 1.1/2oz Bi#4 = a little less than 1.1/4oz Fe#3
- - - - - - - - - - - - - - - - - - - - - - - - - - -
