The Woodruff Gun
Annotations to the Margreiter article.
How Can the 1½-inch Height Difference Described by Herder Be Accounted For?.
Woodruff round shot were fixed. Lead balls were 2.06” diameter and weighed 1 lb. 14 oz. (30 oz.)
The sabot was about 1 3/8” tall, with about a 11/16” depression to seat the ball, so the ball and sabot together was about 2.75” tall.
Woodruff canister was 42 1-oz. lead .69 caliber balls in 6 layers of 7, so the center balls at least of each layer are stacked one above the other. The Ordnance Manual, p. 270, gives the diameter of a .69 caliber ball as 0.685 inch. So total height would be about:
6 x .685” = 4.11” plus maybe a 1/8” base plate, plus the thickness of the canister can, plus a wooden sabot of maybe 1 3/8” (which would allow for a ½” overlap of the canister can on the sabot), or about 5 5/8” tall.
Assumedly these were also fixed.
One researcher has suggested to me that, as a practical matter, the canister rounds would actually have been constructed with only 41 balls, so the top center ball would not protrude above the level of those in the ring around it, the balls in the outer ring of each level being nested into the depressions between the balls in the level below it.
Woodruff conical shot weighed 2.8 lbs. and were about 3.72” long, according to the example at the Atlanta History Center. Based on other information, I think this weight is too low.
The CAD rendering of the conical shot based on the dimensions of the Dickey example yielded a weight in lead of 55.7 oz, or 3.48 lbs., which is closer to the 3 lbs. 5 oz. (3.3125 lbs.) weight of the damaged Berry conical example, which is missing part of the skirt to account for the lower weight. Filley said his conical rounds, assumedly the same as these, weighed “about four pounds”.
According to the OR, when the conical shot rounds were received by the 3rd MSM Cavalry at Pilot Knob, they protruded 1½” out the top of the ammunition box. The difference between the length of the conical shot and the diameter of the round shot is 1.66”, or 1 11/16”, just slightly more than 1½”. For this to account for the difference, this assumes first, that the powder charges for the two solid shot types, one nearly twice as heavy as the other, were similar, which would not have been the practice then, and second, that only solid shot was carried in the ammunition box, when we know Woodruff specified both solid shot and canister rounds for his gun.
Estimates of the ammunition box dimensions, assuming 4 x 5 shot layout within the box, consistent with the size of the boxes based on scaling comparative dimensions off the 1864 photograph, are about 10” wide at the ends and about 8” tall from the bottom of the box to the bottom of the lid. This box is assumed to be sized for round shot and canister only, as the photo was taken in Helen, AR, and the conical shot was only found at Pilot Knob. For a 4×5 shot layout in a box made of ¾” boards, the box is 11” wide and 13¾” long.
Questions:
How large a powder charge would be used for each type of shot?
Steve Cameron of Trail Rock Ordnance, a live shooter, bases the charge on the proportion of the shot weight to the regulation powder charge. Thus the proportion for a 12-pdr. Napoleon is:
2.5 lb. powder / 12.25 lb. total shot weight = .20408
Thus a Woodruff round shot would have a powder charge of:
30 oz. shot weight x .20408 = 6.1224 oz.
For a 2” diameter powder bag, tests show 2 oz. of powder per inch of bag length. Thus a bag containing 6.1224 oz of powder would be 3.06” tall, plus the thickness of the bag, so perhaps 3.1”.
So a fixed Woodruff round shot would have a length of:
2.06” + (1.375” sabot length -.0.6875” depression = 0.6875” net sabot length) + 3.1” powder bag length = 5.8475” or about 5 7/8” tall.
The proportion for a canister round for a 12-pdr. Napoleon, considering just the shot weight, is:
2 lb. powder / (27 balls x 0.43 lb./ball =11.61 lbs.) = 0.17227
Thus a Woodruff canister would have a powder charge of:
42 oz. x 0.17227 = 7.235 oz., a bag then being about 3 5/8” tall.
So a fixed Woodruff canister would have a length of 5.625” + 3.625 powder bag length = 9¼” tall.
This is taller than the apparent visual height of the ammunition box in the 1864 photo. If the interior height of the box is 7.25”, a canister round of that height would have a powder weight of only 3.25 oz., or less than half the expected charge:
7.25” total height – 5.625” height of canister with sabot = 1.625” height of powder, or 3.25 oz.
A Woodruff conical round, originally a Filley round, was probably intended for the rifled Filley version, which represented half of those produced. A lead, hollow-base conical shot, clearly based on the Minié rifle ball, would be assumed to have been intended for a rifled cannon.
The proportion for a solid shot for a 10-pounder rifle (Parrott or Ordnance rifle) is:
1 lb. powder / 9.5 lb. shot weight = 0.10526
Assuming Woodruff conical shot was originally intended for a rifled gun, and assuming the heavier shot weight, would have a powder charge of:
55.7 oz. x .10526 = 5.86 oz., yielding a bag length of 2.93”
So a Woodruff conical shot would have a length of 3.72 + 2.93” = 6.65”, only ¾” more than the length of a fixed round shot and 2.6” less than a canister round.
I assume that the conical shot was not fixed; that the powder bag and shot were separate as with other rifled rounds. It could be possible that the bag was tied onto the grooves in the conical shot body. The OR text does refer to the new ammunition as “cartridges”, which may imply fixed ammunition. I think probably not.
If the ammunition request to the St. Louis Arsenal was for 2.125” shot for the smoothbore Woodruff gun, perhaps the powder bags were produced using the smoothbore powder to shot proportion. Then:
55.7 oz. x .20408 = 11.37 oz., yielding a bag length of 5.68”
So a Woodruff conical shot for a smoothbore would have a length of 3.72 + 5.68” = 9.40”
Summarizing:
Assuming the powder to shot weight proportions for Woodruff shot are comparable to that of more standard pieces:
Woodruff round shot fixed: 5.875” tall
Woodruff canister fixed: 9.25” tall
Woodruff conical shot for smoothbore with bag: 9.4” tall
The difference between the calculated canister length and the length of the conical shot with a smoothbore charge is only 0.15”, so this does not account for Herder’s extra inch and a half.
If the box is really only 7.25” tall inside, the fixed round shot would fit. To fit in the same box, the canister would have to have a charge of only 3.25 oz., as noted above.
For the conical shot to protrude 1.5” out of an 8” tall box, it would have to have a charge of 10 oz.:
7.25” + 1.5” = 8.75” total length – 3.72” shot length = 5.03” x 2 oz./in.= 10.06 oz.
This would be a powder to shot weight ratio of:
10.06 oz. / 55.7 oz. = 0.18061
The Ordnance Manual for the Use of Officers of the United States Army, Third Edition.
How does the Ordnance Manual show the powder weight to shot weight proportion?
Solid shot:
12-pdr. Gun:
Weight of powder: 2.5 lbs. (p. 280)
Weight of shot alone: 12.25 lbs. (p. 34)
Powder to shot proportion: 0.20408
Weight of shot, “ready for fixing”: 12.75 lbs. (p.280)
Powder to shot proportion: 0.19608
6-pdr. Gun:
Weight of powder: 1.25 lbs. (p.280)
Weight of shot alone: 6.1 lbs. (p. 34)
Powder to shot proportion: 0.20492
Weight of shot, “ready for fixing”: 6.25 lbs. (p.280)
Powder to shot proportion: 0.2
Shot alone proportion difference: 0.20492 – 0.20408 = 0.00084
“ready for fixing” proportion diff.: 0.20000 – 0.19608 = 0.00392
Canister:
12-pdr. Gun:
Weight of powder: 2.0 lbs. (p.280)
Weight of shot alone: 0.43 lbs. x 27 = 11.61 lbs. (p. 36)
Powder to shot proportion: 0.17227
Weight of shot, “ready for fixing”: 14.8 lbs. (p.280)
Powder to shot proportion: 0.13514
6-pdr. Gun:
Weight of powder: 1.0 lbs. (p.281)
Weight of shot alone: 0.21 lbs. x 27 = 5.67 lbs. (p. 34)
Powder to shot proportion: 0.17637
Weight of shot, “ready for fixing”: 7.32 lbs. (p.281)
Powder to shot proportion: 0.13661
Shot alone proportion difference: 0.17637 – 0.17227 = 0.00410
“ready for fixing” proportion diff.: 0.13661 – 0.13514 = 0.00147
In no case do the proportion differences between shot alone and “ready for fixing” (including the weights of sabots, etc.) amount to as much as 0.5%.
In the absence of information about the sabots, etc., for Woodruff projectiles, using the shot weight alone for establishing powder weight by proportion to shot weight seems to be an acceptable method.
