Civil War Cannons and Artillery

Seacoast Artillery Company


Civil War Union Artillery

Civil War Cannons - Parrott 100 Pdr

Parrott 100 Pdr
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Civil War Confederate Artillery

Civil War Cannons - 7 Inch Brooke

7 Inch Brooke
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Civil War Cannons

100 Pdr Parrott Function

Rifling:

Because we built our own rifling machine, we designed it to have features well suited to produce our specialty, which is “blind hole rifling”. This means rifling a bore that is open on one end only. Also our unique design allows us to produce “gain-twist” rifling just like the original guns had. The 100 Pdr. Parrott Rifle, Model 1861 had gain-twist rifling that went from zero twist in front of the chamber to one turn in 18 feet at the muzzle. Our 1/6th scale rifling goes from zero to one turn in 3 feet, (36”), at the muzzle. This twist is more than adequate to stabilize our 1/6 scale projectiles. The 9 lands/ grooves are of equal width. The groove depth is 1/6th of the original’s 100 thousandths of an inch deep.

Accuracy/Range:

Our tests at 100 yards indicate clearly that our 7 ounce, solid steel(12L14), milled base, truncated cone nose, test projectiles which we fired, cut perfectly circular holes in the targets. This is a good indicator that the errors of instability are NOT present in our test results. We believe our very careful and methodical rifling process produces superbly accurate rifling which delivers projectiles to the target without pitch or yaw errors. The ballistics program we use calculates a max range of 3,500 yards more or less depending on the powder charge, so be very careful about the tube’s elevation if you decide to shoot your seacoast gun. Accuracy depends very much on the cannoneer’s skill and weather conditions, but our tests indicate that the accuracy of 5 shot groups can be expected in the range of 2 to 4 inches depending on the gunner’s skill and willingness to go through “load development” process. We are talking about 100 yards here. With extra gunner care and elimination of all possible variables and with excellent sighting technique and excellent wind-doping skill, 5 shot groups of less than 3 inches center to center can be achieved.

Eccentric Axle:

Two artillerymen pulling down on two eccentric axle wrenches rotated the upper carriage wheels down into contact with the I-beam rails. This forced the approximately 13,000 pounds of the tube and the upper carriage up off the rails and facilitated the crew’s movement of the gun into “battery” or firing position. On our 100 Pdr. you can lift the approx. 55 pounds off the rails with two fingers. This 19th century design re-created by Seacoast Artillery Company really works !

3 Deg. Rail Pitch:

The 3 degree chassis rail incline which is higher at the rear of the chassis works very well to burn off excess recoil energy which moves the tube and upper carriage to the rear. This movement, if unchecked, will propel the 55 pound mass right off the back of the chassis! By forcing this mass to go up the incline, the designers knew that some energy would be expended in moving the mass upward, which, in turn, would reduce the amount of energy available to move the carriage to the rear.

Counterhurters:

These friction brakes are used in conjunction with the 3 degree rail pitch to retard carriage movement to the rear during recoil. About one half of the historical photos show the two devices near the ends of the rails and the other photos show them at some mid-point between the back of the upper carriage and the end of the chassis rails. After firing our test gun over 150 times, we believe that the heavy artillerymen of the Civil War assigned to these large Parrott Rifles used the counterhurters drawn up tight behind the upper carriage cheeks. The distance the upper carriage recoils can be regulated by the amount of compression applied to moderately or tightly bind the counterhurters to the I-beam rails.

Chassis Wheel Forks:

The front wheel forks are machined to duplicate the original compound angle which the wheel faces present to the plane simulated by the surface of the traverse circle track segments. A combination of a 15 degree angle of wheel attack to the Circle of traverse with the 6 degree pitch out at the bottom of the front chassis wheels and the 3 degree cone of the wheel contact surface, itself. All these angles work together to allow easy 360 degree rotation of the gun about the pintle-pin without wheel slippage, skidding or crabbing.

Sights:

The sights are completely functional. The front sight is a simple blade screwed into the front sight boss, called the front sight mass in the 1860s, which is located just above the right rimbase near the right trunnion. The rear sight is anything but simple, however, and is quite challenging to make. The graduated staff, 0 to 10, has a small pin on the back, just as the original did to align the peep sight leaves square to the bore axis. This pin fits into a small internal key-way groove in the through-hole in the rear sight holder ball located in the upper-right quadrant of the rear breech face. The left-hand thumb screw on the slider secures the slider in any position on the staff. The right-hand thumb screw rotates the sight leaf piece and moves the peep sight leaf assembly to the left or right for an effective windage adjustment.

 


Parrott 100 Pdr

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