Commanding Second Brigade, Second Division
Pursuant to your order, I have the honor to submit the following report on the Sims-Dudley pneumatic gun. The gun has now been in action three times, namely, at the Battle of Santiago, on July 1, and at the subsequent bombardment of that city on July 10 and 11. In all 20 shots have been fired, resulting in the destruction of three Spanish guns, the extensive demolition of trenches, and presumably a considerable loss of life to the enemy. It may therefore be asserted that as a destructive agent the gun is a success, and justifies the claims made for it by its makers in this respect. The test, however, to which the gun has been put has been equally serviceable in laying bare certain faults in material and construction, which not only mar the efficiency of the gun, but add greatly to the danger attending its operation. Briefly summarized, these faults are as follows: First, the extreme fragility of the breech mechanism, due to the lightness of construction and character of metal used. This was demonstrated after the first shot, when the extractor failed to work and has since proved useless. This alone has been an effectual bar to rapid fire, and has greatly reduced the efficiency of the piece. Subsequently, the brass handle on the firing pin broke off, owing to a flaw in the metal composing the pin, and finally the lower end of the trigger broke, owing to the crystallized condition of the steel of which it was made. I have further noted a tendency on the part of the firing tube to slip back through the bands designed to hold it in its position relative to the pressure chamber, and while I have retarded this by tightening the bands, still it is a serious fault, inasmuch as if allowed to go unnoticed it would eventually cause a break at the breech, which could not result otherwise than in serious loss of life to those in the vicinity. All of these defects can easily be remedied by the makers, as can also the defect in the powder cartridge, the shell of which is so light that it expands and jams on explosion, and ma be said to have been the initial cause of many of the difficulties to which the gun has been subject. These shells must be given more weight and rigidity. As to the equipment of the gun for field service, I would suggest that it be rigged as nearly as possible like our light artillery pieces, with such modifications as are necessitated by the difference in construction of the pieces. The small trial wheels as at present arranged are quite useless.
I am, sir, your obedient servant,
HALLETT ALSOP BORROWE
Sergeant, First U.S. Volunteer Cavalry
Dynamite Gun Detachment