Civil War Union Artillery
 Parrott 100 Pdr
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Civil War Confederate Artillery
 7 Inch Brooke
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Civil War Cannons
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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.
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