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(5 plates.)

This gun was transferred to the “ Board for Testing Rifled Cannon, &c.," for test, by instruction from the Chief of Ordnance, U. S. Army, dated February 3, 1885.

September 18, 1885, the Board made a progress report covering the first 16 rounds fired from this gan. (See Appendix No. 48, page 48, Report of Chief of Ordnance, U. S. A., for 1885.)

The Yates rifle is a conversion from 10-inch Rodman smooth-bore gun No. 182 (West Point foundry), by lining with a Nashua steel tube, attaching a cast-iron extension piece to the muzzle of the casing and applying the Yates breech mechanism of Midvale steel. For the detailed description of the gun, dimensions, weights, &c., the Board respectfully refers to the construction report of the 8-inch Yates rifle, made by the Inspector of Ordnance at Boston, Mass.



The body or casing consists of the 10-inch Rodman smooth-bore gun above mentioned, pierced through the breech and lengthened by screw. ing a cast-iron extension piece on the muzzle. The portion in rear of the trudnions is turned off, and circumferential grooves are cut in the exterior to receive corresponding interlocking fillets on the breechclamps. The bottom of these annular grooves form cylindrical surfaces 28 inches in diameter. The diameters of the projecting annular fillets or recoil shoulders on the body are as follows: The rear one 29.9 inches, the two forward shoulders 30 inches. The planes of the bearing surfaces of these shoulders are perpendicular to the axis of the piece. The longitudinal sections of the projecting annular fillets are trapezoidal. The radius of the breech is 34 inches; and the spherical zone tangent to and connecting the breech with the cylindrical body has a radius of 11 inches. (See Plate I, Figs. 1 and 2.)


The tube is made of Nashua (N. H.) steel, is cylindrical on the exterior, and has a cylindrical shoulder near the rear end. It is retained

by a securing pin on the under side, placed 3 feet 6 inches in front of the axis of the trudnions.

The chamber and rifled portion of the bore are concentric. The chamber has 3 conical and 2 cylindrical surfaces. The rear end of the chamber is recessed for the insertion of the gas-check by a counterbore .45 inches in depth. The rear conical surface is 11.7 inches in lengtlı and extends forward from the bottom of the counterbore, and is in. tended to support the walls of the long “ cartridge head" or gas check, and to facilitate its removal.

A vertical slot is cut below the axis of the chamber and in the rear end of the tube to permit the use of an extractor in case the gas check sticks in its seat.


These two clamps are made of Midvale steel. They are symmetrical, cylindrical, and rounded in rear. The clamps embrace the breech of the casing like a shell, and are pivoted and held together by two assembling bolts, one screwed into the upper surface of the casing, and the other into the lower or under surface. The interior surface of the clamps corresponds to the exterior surface of the casing before described. Grooves are cut in this surface to correspond with the annalar fillets on the exterior of the casing.

The axial portion of the interior surface of the clamps receives the pressure exerted upon the cartridge head” or gas check and transmits it through the cylindrical walls of the clamps to the recoil shoulders on the cast iron casing.


This is intended to operate the breech mechanism and is pivoted beneath the body of the gun. It has two curved cam slots, one on each side of the pivot, which engage the cam pins attached to the two breech clamps. The lateral swing permitted by these slots is sufficient to expose the rear end of the chamber for the purpose of loading.


The original locking device was a hooked lever attached to one clamp above the center of the breech, which caught upon a pin in the other clamp when the mechanism was closed. It was furnished with a flat retaining spring of steel.


This consisted of a hammer actuated by a lanyard and a firing pin. A spiral firing-pin spring was inserted to retract the firing pin after the discharge of the piece. Instead of a friction or other primer, a 22-inch caliber pistol cartridge was designed to ignite the charge.


A radial vent was placed in the cartridge head" or gas check to receive the priming cartridge which was exploded by the axial firing pin seated in a cylindrical lug in one of the breech clamps.

The above-described firing device and vent were abandoned after the sixteenth round, and an ordinary radial vent was inserted 10 inches in front of the bottom of the chamber.


This gas check was made of composition metal or bronze, and was called the “cartridge head” by the inventor. Its exterior form was similar to the metallic cases of small-arm cartidges. The exterior of the head corresponds in curvature to the breech of the gun. The bottom on the interior was hemispherical, with a radius of 4 inches. It had an axial vent bushed in rear with a steel disk,


168 160

8 135. 25

24.75 133. 25 26.75

Total length of gun
Total length of bore.
Diameter of bore..
Length of rifled portion of bore (original).
Total length of chamber (original)
Length of rifled portion of bore (after 16th round)
Total length of chamber (after 16th round)
Breech clamps (two):
Thickness of metal:

At bottom
At shoulders
At 1st groove
At 2d groove

At 3d groove
Radius of breech :

Exterior (bore)..

Interior (bottom)
Number of recoil shoulders (casing and clamps), 3 each.

8 2.5 1.53 1.58 1. 75

32 34

Total weight of gun
Weight of clamps..
Weight of “cartridge bead," or original gas check

Pounds. 18, 540 3,452

48.5 327


The rifling is polygroove, with an equal number of lands and grooves.


Number of grooves....
Grooves :

Width ...

Bottom rounded with radius of


Rounded with radius of.. Twist, uniform, one turn in..

...inches.. 0.3884 0.06 .do... 0.06

.do.... 0.17 0.01

. feet.. 30


From data furnished by Colonel Yates, the metal of the clamps possessed the following physical properties, viz:

Elastic lim- Tenacity
Number of

it (pounds (pounds per

per square square

inch.) inch.)


Per cent.

[blocks in formation]

6.5 8.5


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The marks left upon the head of the gas check in the early firings indicated that one of the clamps yielded more than the other. At the fourth round the right clamp alone was found to be bearing properly ; the left clamp was found to be bearing at the end of the seventh round.


The inventor, Colonel Yates, was allowed to be present during the trials, and to make whatever changes he desired in the gas check, vent, or breech mechanism upon the approval of the Chief of Ordnance, U. S. Army, and to make any changes he desired when done at his own expense.


These were all made at the Ordnance Proving Ground, at Sandy Hook, New Jersey.


The 8-inch Hotchkiss projectiles and Du Pont's hexagonal powders E. V. L. and E.V. K., density 1.750 and granulation 72, were employed in all the firings.


The Board decided upon firing 500 rounds, with 35 pounds of powder and 180-pound projectiles, as a test for endurance.


The gun was star gauged after the 5th, 8th, 16th, 26th, 59th, 114th, 154th, 220th, and 259th rounds.


Vent. After the 16th round a radial vent was inserted in the vertical plane through axis of bore and on top of the piece to replace the axial vent in the breech.

Chamber.—This was lengthened 2 inches at the same time the vent was changed.

Locking device. The fat retaining spring broke at the 6th round. After the 10th round a new and heavier locking catch of steel was substituted for the original one. After the 13th round the steel locking catch was replaced by one of wrought iron 1.25 inches thick and 5 inches wide, litting over two 2.25-inch steel pins. After the 14th round a new locking plate and a new pin on the right clamp were put in. After the 16th round, the latching devices for locking the breech clamps being insatisfactory to the inventor, he replaced the latches and pins by a steel cap with a retaining device for keeping it closed. (Plate I, Fig. 3.) A cylindrical tenon, 1.5 inches long and 12 inches in diameter, one-half upon rear of each clamp, was turned, over which a rounded cylindrical cap, about 12 inches interior diameter and 18 inches exterior diameter, was fitted. This cap was hinged to one clamp and latched to the other. The other changes were made at the request of the inventer, under his supervision, and in accordance with his letter (Ordnance Of fice, No. 104 I, of 1885). In a letter dated September 25, 1885, the in

ventor, Colonel Yates, says, in relation to this cap over the rear end of the clamps :

It is rather awkward to manipulate, and it takes as much time to free it as it docs to open and close the sections.

The clamp employed was suggested by me, but has nothing to do with the system; is peculiar to this gin, and would not be used on another.

In firing for rapidity, I do respectfully ask that ihe Board will give the above facts due consideration.


Several gas checks were employed during the course of the experiments. Below will be found a brief sketch of these obturators:

No. 1. Original gas check or "cartridge head.(Plate II, Fig. 1.)-This was made of composition metal or bronze, and has already been sufficiently described. Its principal dimensions are as follows: Total length.

..inches.. 12.00 Length of body 11. 25 Diameter, exterior: Front end....

.do.... 8.25 Rear end....

.do.... 8. 67 Head

.do... 9. 25 Radius of base-exterior.

.do.... 34.00 Interior: Total length...... 11.00 Diameter, conical part, front base 8.05 rear base 8.00 Radius of bottom.. 4.00 Thickness of metal, front end.. 0. 10 at bottom (on axis). 1. 00 Weight....

pounds.. 48.50 After the 2d round, one-sixteenth-inch was turned off the lip and the exterior surface was turned off slightly; after the 3d round another one-sixteenth inch was taken off the lip and the surface was eased as before; after the 4th, 5th, and 6th rounds the exterior was filed slightly to make it fit the chamber easily. Number of rounds fired, 7.

Gas check No. 2 (Plate II, Fig. 2).-This was No. 1 gas check cut off to u inches in length and the hemispherical interior turned out to cup shape, with the exterior reduced by filing. Number of rounds employed, 1 (No. 8).

Gas check No. 3.—Steel gas check, 9 inches long; used for firing rounds 9 to 13, inclusive, 5 rounds.

Gas check No. 4 (Plate II, Fig 3).- A compound gas check, consisting of a copper cup pinned to a steel base ; used from the 14th to the 124th powds, inclusive, 111 rounds. Before firing the 60th round the lip of the copper ring was shortened eleven-sixteenths inch and the rini on the steel bead filed circumferentially. Gas check readjusted before the 98th, 100th, and 102d rounds.

Gas chick No. 5 (Plate II, fig. 4).-Steel gas check substituted for compound one. During the firing of this gun the gas check was reipoved, washed ou exterior with wet cotton waste, and then wiped with oiled waste. The seat in the gun was wiped out after each round. This check was used from the 125th to the 220th rounds, inclusive, 96 rounds.

Gas check No. 6 (Plate II, Fig. 5).-New steel gas check. It was in. Herted and removed easily with the hook before firing. Stuck after fir. ing, and removed with considerable difficulty with a lever. Examination showed a slight distortion of gas check due to eccentricity in the seat. Used during 1 round (the 221st).

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