Having been requested by the Naval Institute to contribute an article under the above title, I have compiled such data and records as may be of interest to its readers. It has been my intention to avoid, as far as possible, drawing any comparisons between this and any other special system. As this publication circulates mainly among men familiar with the results obtained from other guns of this class, comparisons can be easily made from the data here given.
It may fairly be said that the rapid-fire gun is a new improvement in ordnance, as the guns ordered for the Chicago, Boston, Atlanta, and Dolphin were the first ordered by any government. Other nations soon followed, and some had guns of this class actually in service before the United States, owing to the fact that these ships were not ready to receive them for some time after the order was placed. From that day to this the importance of this class of ordnance has gradually increased, and is likely to increase still further. From being present only in the secondary batteries it has found its way into the main battery, and its caliber has been expanded from that of the 6-pounder to that of the 100-pounder.
To discuss the advantages of this class of ordnance in general would occupy more space than allowed to an article of this kind. I will therefore confine myself to describing- the particular design of the Driggs-Schroeder.
At the time this gun was designed there was no place in the country where the Navy could obtain ordnance of this type. Even had the Department been inclined to purchase its guns from foreign countries, Congress effectually forestalled this by an act requiring the new ships to be throughout of domestic manufacture. There was, therefore, no course open except to induce manufacturers to start the building of these guns in the United States.
As the most successful gun of that day was the Hotchkiss, that company was offered an order for some 94 guns and a considerable amount of ammunition to induce them to build in this country. This order was accepted and the manufacture of the guns placed in the hands of the Pratt & Whitney Co., of Hartford, the ammunition being made by the Winchester Arms Co., of New Haven, About the time this order was placed with the Hotchkiss Co., an experimental 3-pdr. Driggs-Schroeder gun was made and submitted for trial at Annapolis. The results were all that had been anticipated, but the authorities hesitated to endorse the system until after the successful trial of a larger caliber. A 6-pounder was therefore built, and after successful tests, during which some 150 rounds were fired, under all conditions of service, an order was placed with the Driggs Ordnance Co. (which had been organized after the trial of the experimental 3-pdr.) for 20 guns (10 3-pounders and 10 6-pounders). This order was soon followed by an order for 30 more 6-pounders, on condition that the first gun delivered under the first order should pass a successful test of 200 rounds in 4 consecutive hours. This having been accomplished without any failure whatever, an order was placed with the Driggs Ordnance Co. for 75 additional 6-pounder guns. The experimental 6-pounder, after passing through the tests at Annapolis, was sent to Bridgeport for testing ammunition, and has now fired upwards of 400 rounds, without having any repairs whatever put upon the mechanism. The other 6-pounder gun tested at Annapolis, as mentioned above, has now fired about 350 rounds. No repairs have been put upon it, except the replacing of a small spring in the handle, which was injured in transporting the gun.
A 3-pounder gun has just passed through a very severe trial in England, conducted by the English government.
The general construction of the gun is as follows:
The jacket, in two parts, the forward one of which is termed a sleeve, is shrunk upon the tube, the two parts being connected under the trunnion-band by the screw-thread of the latter. A jog in the adjacent surfaces of tube and sleeve transfers to the trunnions the thrust imparted by the rifling. The breech mechanism is contained in the rear of the jacket, which forms a natural housing and protection for the same.
The trunnion-band is not shrunk on the gun, but simply screwed on tight and pinned to prevent turning. In the guns built for the navy it has been omitted entirely, the gun screwing directly into the sleeve of the recoil mount.
The construction of all the guns is the same in principle. There is a slight change made in the 1-pounder, for the reason that it was intended to shift this gun about and to use it as a subcaliber piece for the large broadside guns. It was therefore thought best not to trust to the mounting to lock the tube and jacket, so for this purpose the sleeve was both screwed and shrunk on.
The general construction of the 6.pounder is shown in Plate A.
In favor of the guns themselves, independent of mechanism, attention is invited to their weight and length, high grade of steel, and the strength of the gun. Their length of bore is 45 calibers—longer, we believe, than any guns of their weight and strength in the world, and certainly longer than any guns of their weight in the United States.
The steel used is of the best quality, furnished by the Midvale Steel Co. and the Bethlehem Iron Co. The records of the Government Inspectors at these works show the steel used in the forgings to possess the following qualities:
Tensile strength, 90,000 to 135,000 pounds per square inch.
Elastic strength, 50,000 to 80,000 pounds per square inch
Elongation, 15 to 30 per cent of its length.
Contraction, 20 to 50 per cent of its area.
These formulae, while not making so good a showing for strength of gun, are still the most reliable to work upon in constructing built-up guns.
The factor of safety is about 50 per cent, so that the actual elastic strength of the Driggs-Schroeder 6-pounder is about 30 tons per square inch. The ultimate or tensile strength of this caliber is about 40 or 45 tons per square inch, depending on the quality of the steel used.
The tube and jacket are proportioned, as near as possible, so that the exterior radius of tube will be a mean proportional between the interior of tube and exterior of jacket. This cannot always be done, but the nearer the approach to this proportion the stronger the construction. In all the Driggs-Schroeder guns this point is very nearly reached, and therefore the design is, theoretically, as near correct as it can be made.
The breech-housing being closed at the top excludes dirt and rain, while it is a great support to the rear end of the chamber.
It has long been known that guns on the sliding-wedge principle were faulty in construction, because the breech-block, being held to the body of the gun simply by two side-pieces, the repeated strains brought these sides closer together and changed the shape of the chamber from round to oval.
GREATER RANGE, ACCURACY AND PENETRATION FOR THE SAME WEIGHT OF GUN.
The rapid-fire 3- and 6-pounders which were first put in service in this country had a length of bore of 40 calibers. Much of the weight of the gun was taken up in the weight of the breech mechanism and its housing.
When the Driggs-Schroeder was designed, a large amount of weight was saved at the breech, so that it would have been possible to make a 40-caliber gun on this design weighing some 50 pounds less than those in service at that time, but it was thought better to use the metal saved at the breech towards strengthening the chase and lengthening the bore. This was done, the bore being lengthened five calibers.
This increase has put from 40 to 70 f, s. on the muzzle velocity of the shell, depending, of course, on the loading. On this point, the report made on the first 3-pounder tested at Annapolis, which was about 44 calibers length of bore, was as follows:
"Theoretically, the increase of velocity due to four calibers increase length of bore is about 70 f. s. The results of practice show that the theoretical conditions are fulfilled.
The following velocities were obtained:
Charge, 763 grams N. D.
Projectile, Hotchkiss common shell, 1500 grams.
I. V. 2042 f. s.
2052 f. s.
2042 f. s.
2057 f. s.
2046 f. s.
Mean 2048 f. s.
The tests made on this point show that there is no difference between the pressures in this and in the Hotchkiss guns of the same caliber, the powder and projectile being the same."
The advantages therefore claimed for the Driggs-Schroeder guns (distinct from those claimed for the breech mechanism, mentioned later) are:
1. For same weight and strength of gun, greater range, accuracy and penetration.
2. A natural housing for breech mechanism.
3. More reliable construction.
2. BREECH MECHANISM.
The essentials of a good breech mechanism for any system of rapid-fire guns are:
2. Ease and rapidity of working breech mechanism.
3. Certainty and force of extraction.
4. Protection of mechanism.
5. Complete ejection of the empty case.
As regards this essential, the strength of the breech-block and its support, in the Driggs-Schroeder gun, is sufficient in the 3-pounder to sustain a chamber pressure of 60 tons per square inch, and in the 6-pounder 70, without in either case passing the elastic strength of the metal. The usual working pressure is only 15 tons per square inch. For further proof of the safety of the mechanism we quote from official reports on 3-pounder:
"The maximum pressure developed in the bore has been 18 tons. Under this and the frequent repetition of lower pressures (about 12 to 15 tons) the block has shown no signs of weakness.
If fully closed before firing, it is, I think, amply strong both in itself and in its support.
Experiments were made to determine whether the cap could be snapped and the gun fired before the breech was fully closed.
There was found to be no possibility of such an accident, the arm of the cocking cam being always interposed to prevent the firing pin from striking the cap until the breech is locked.
It is a feature of this system which gives it an advantage over certain others that the firing pin may be set and kept at half-cock. Tested in this position, it is found to be free from danger of accident.
It may be said, therefore, that the safety of the system is at all points satisfactory."
Report on 6-pounder is as follows:
"The new locking device answers its purpose well. No liability of its being jarred or knocked open while firing was noticed. It was found there was no possibility of firing before the breech was closed and locked.
The strength and endurance of all parts appear to be sufficient."
EASE AND RAPIDITY OF WORKING BREECH MECHANISM.
The lightness combined with a revolving motion of the breechblock results in increase of rapidity of firing and decrease of fatigue in working. This is further augmented by the fact that the cartridge need not be accurately placed. If the case is within three-fourths of an inch of being home, the motion of the breech-block will complete the loading as well as if the rim of the case was close against the extractors.
The breech-block of the 6-pounder Driggs-Schroeder gun weighs 26 lbs.; the corresponding part of the other 6-pounders in service weighs 59 lbs. The difference in the 1 and 3-pounders shows the same proportion of decrease.
This saving of weight is an important factor in rapid firing, especially if the maximum rate of fire is continued any length of time. Without doubt there is a great difference between the rate of fire of aimed and unaimed shots, and also the rate at which ammunition can be supplied will limit in a degree the rate of fire. This fact is brought forward by some ordnance men to sustain an assertion that there is no advantage in increase of rapidity of operating the breech mechanism. The supply of ammunition is not changed by changing the breech system ; neither is the time occupied in pointing. The only operations, therefore, that vary with the change from one system to another is the loading and extracting. It is obvious, therefore, that the less time is occupied in these operations the less time there will be between the different shots, and this will be the case whether the gun is aimed or unaimed.
Ammunition is supplied in boxes containing from 11 to 40 rounds, so that the supply of ammunition would not change the rate of firing a volley, though it might change the time between the volleys.
It is plain, therefore, that the gun that can fire the greatest number of unaimed rounds can also fire the greatest number of aimed rounds, allowing the same time to each for pointing.
No test has ever been made in this country to determine the rate of aimed fire for any rapid-fire gun, so that no data on this point is at hand. The rate made with the Driggs-Schroeder 3-pounder, with an untrained crew, was 33 rounds per minute. This speed was attained on an official trial in England. The rate actually made in this country with the 6-pounder gun was 25 shots per minute, which was also accomplished with an untrained crew. This same crew (consisting of but 3 men) fired 61 rounds in 3 m. 36 sec. The official report on this part of the test is as follows:
"The rapid-fire test of 60 rounds, fired as rapidly as possible, was commenced at 11.05. The start was made with the breech open, and a cartridge in the hands of No. 3."
PROTECTION OF THE MECHANISM,
The housing for the breech mechanism is only open at the bottom and rear, so that the mechanism is entirely protected from shot or falling fragments ; the only pieces exposed are the pistol-handle on one side and the operating-handle on the other. Even were the pistol-handle shot away the gun could still be worked, and almost as efficiently as with it. In designs having the housing for the mechanism open at the top, falling fragments are apt to lodge there, rain beats in, and on shore sand and dust will collect in the mechanism. Besides this, a breech-block supported only at the back requires much more metal in the housing than should be put in this part of the gun.
In almost every system using a sliding or vertically moving block this part of the mechanism projects beyond the housing both at top and bottom, so that even when the gun is closed the breech-block, which is the keynote of the whole mechanism, is at all times exposed to accidental blows or injury in action.
The use of the screw-plug for rapid-fire guns is even worse.
In all the systems devised to utilize this mode of closure, almost the entire mechanism is exterior to the gun. To perform the many motions necessary for the plug to go through requires a complicated system of cogs and levers. The plug must be revolved, withdrawn and swung around on a tray ; all with one motion of the handle. On the tray the plug is only held in place by the friction due to its own weight on a movable knuckle. The whole mechanism must be entered and withdrawn at every fire. A slight displacing of the breech-block in the tray (which is an easy matter) will prevent the plug being returned to the gun.
During all the operations of loading the whole mechanism is out of the gun and at the side, exposed to accidents of all kinds.
Peculiar as it is, it is still a fact that many officers think that any system using the interrupted screw-plug is good because it utilizes that closure, and yet this same interrupted screw-plug has a longer record of accidents, injuries and deaths than all the others put together. Very few professional men who read this paper but who can recall some serious accident from the use of the screw-plug breech-closure. They invariably have an explanation of the cause, but that is little satisfaction to the victim or to his friends.
The advantages, therefore, of the Driggs-Schroeder system over others may be condensed as follows:
1. No danger can result from a hang-fire or misfire.
2. The gun can be left loaded and half-cocked and can be cocked again without opening breech.
3. The mechanism is thoroughly protected from small shot and accidental blows.
4. The breech-block is 50 per cent lighter than some other systems, and lighter than any known, from which results:
5. Greater length of gun for same weight. This results in:
6. Greater velocity and therefore greater muzzle energy.
7. (4) also results in a greater rapidity of fire over other systems of from 5 to 10 shots per minute.
8. Since the block revolves, the full weight of the block is only felt for an instant.
In long-continued firing this would be of the greatest importance to the operator.
9. From (4) it is evident that the system can be carried to heavy guns.
The block of the Driggs-Schroeder 36-pounder only weighs 68 pounds, the full weight of which is only felt for a drop of one inch.
10. The shoulder- piece is on the right side, which is the natural position to fire.
11. Three men only are required for a crew.
12. The handle being on the left side, the loading and operating is done on the left side of the gun. This leaves the captain of the gun (who is on the right side with his right shoulder against the shoulder-piece, and the right forefinger on trigger) with a clear field of vision, so that pointing and loading go on together.
13. The cases need only be pushed to within one inch of extractors. Regarding the handling and pointing of the piece we quote from the official report upon the Driggs-Schroeder guns, tested at Annapolis, as follows:
"The shoulder-piece of the gun is on the right-hand side and the handle on the left. There result from this arrangement, taken with the lightness of the block, certain marked advantages.
The man who works the handle is on the left of the gun. He can work the handle perfectly with the left hand, which leaves his right hand free for loading and inserting the cartridges.
We found in actual firing not only that this arrangement, which does away with one man and reduces the crew of the gun to three, is practical, but that it is much better than to have four men. As the same man inserts the cartridge and closes the breech, there can be no danger of jamming the cartridge or the hand by starting up the block too soon."
DESCRIPTION OF THE BREECH MECHANISM.
Referring to the drawings. Fig. 1 represents a longitudinal section of the breech end of the gun and the breech-block, the cam and firing-pin being shown in side elevation, and other parts and features in dotted lines. Fig. 2 shows the same with the breech-block moved back into position for opening the chamber for the introduction of a cartridge. Fig. 3 is a rear elevation of the breech of the gun, with the breech-block closing the chamber, and a number of other parts and features shown in full and dotted lines. Fig. 4 shows a detail side view of the breech-block. Fig. 5 shows a front view of the same. Fig. 6 is a rear view of the cam in detail. Figs. 7 and 8 are respectively side and rear views in detail of the extractor-arm for the right side of the breech-block. Fig. 9 is a detail side or edge view of the sliding leaf for holding and releasing the firing-pin. Figs, 10 and 11 are broken horizontal sections of the breech-block and sliding leaf, said sections being respectively taken on the dotted lines x x1 and y y1, Fig. 3. Fig. 12 is a vertical section of a part of the breechblock on the dotted line 2 2 of Fig. 1, showing the form of the cavity at that point. Fig. 13 is a broken side view of the breech and the operating handle, showing the spring-catch in the latter and the recess therefor in the former.
In the drawings, A represents the breech-block, which is provided on its upper surface with bands a a, which fit into correspondingly shaped grooves or recesses a' a! in the upper interior surface of the breech A' , and extend downward a suitable distance within the walls of the breech A1. These bands and their grooves firmly hold the breech-block in position and prevent backward movement of the same during firing.
The breech-block A is formed with a cavity, A’, extending from the front toward the rear, the general contour being represented in longitudinal and transverse section in Figs, 1 and 12. Formed in the front part of the cavity is a curved wall, 1 2, of suitable length, which merges into an upwardly inclined wall, 2 3, and in the rear upper part of the rectangular portion of said cavity is a round pin, 4, immovably secured therein.
The central front face of the breech-block containing the cavity is covered by a strong face-plate, 5, which is held in place by a locking plug, 6, screwed into the same and the cheeks of the cavity.
In the sides of the breech-block are formed cams or guide-grooves 7 7, which are of the shape shown in dotted lines in Fig. 1 and full lines in Fig. 4, their lower or rear walls from 8 to 9 being nearly vertical, but slightly inclined forwardly. From the point 9 said guide-grooves continue on in curved lines from point 10 to point 11, the two latter points of said grooves being concentric with the axial bolt when in the upper part of the elongated opening in the breech-block, the purposes and functions of these parts and features being hereinafter fully described. Projecting into the guide-grooves 7 7 are guide-studs 12 12, which are secured in the walls of the breech. The elongated opening 13 is also formed in the breech-block—in its lower portion—and is inclined forward two or three degrees from the vertical, so as to allow of a movement of said block when closing. A strong axial bolt B passes through said elongated opening, fits in openings in the walls or cheeks of the breech, and extends out beyond the same on the left side, where it is provided with an operating handle, b.
In the upper part of the cavity in the breech-block, or above the rectangularly shaped part of said cavity, is arranged the firing-pin C, which is provided at its rear end with a finger-loop c, and at its front end with an upturned head, c' . On the under side of this firing-pin, toward its rear end, are respectively formed half and full cock-studs, c" and c'" , and a downwardly and forwardly extending cocking-lug c"" is arranged near its middle. In the top portion of the cavity, above the firing-pin, is arranged a spiral spring, D.
In the left upper end of the cam E, and extending its full width, is formed a circular recess, e, which is struck with the same radius as the rounded pin 4 in the cavity of the block. Beneath said recess e and in the middle of the upper rear part of the cam, is formed a larger curved and walled recess e’ as shown in dotted lines in Fig. 1 and in rear view in Fig. 6, which terminates in front at the point e" of the cam. This point, when the breech-block is closed, rests beneath the curved wall 1 2 of the cavity and supports said block in raised position. At the rear lower end of the cam is a toe, e'", which, when said cam is turned backward, exerts a downward pressure upon the lower wall of the cavity in the breech-block and cams the block down.
In the rear of the breech-block is located the sliding leaf F, which holds and releases the firing-pin, and which fits in a mortise cut in the rear face of the block and extends downward from the hole for the firing-pin. Side views of this sliding leaf are shown in Figs, 1 and 9, and transverse sections of the same and its mortise in Figs. 10 and 11, which are respectively views on the dotted lines x x1 and y y1 of Fig. 3. A coiled spring/ is located in a vertical cylindrical recess, f', in the rear wall of the breech-block and presses the sliding leaf up against the firing-pin. The top of this spring bears against a flat circular lug f" on the front side of the leaf. The spring is introduced at the bottom of said recess and held in place by a plug f"'. From the rear face of the leaf projects a laterally extending arm, G, which terminates in a lip g having a rounded rear face as shown in Figs, 1 and 9. A vertical slot g' is formed in said arm, and a screw-stud g" passes through the same and into the block, whereby the vertically sliding leaf is kept in proper alignment.
A small rock-shaft, H, passes transversely through the right wall of the gun-breech, and its inner end terminates in a recess in said wall in rear of but out of line with the side of the breech-block. On the inner end of said rock-shaft is a trip or finger, h, which is normally just in contact with the rounded lip p; of the laterally-extending arm G of the sliding leaf F, while on the outer end of said rockshaft is secured a finger-piece or trigger, ll, which projects downward beneath the usual hand-rest or pistol-grip, l and which, on being pressed by the finger, causes the trip h to bear down upon the lip g of arm G, and thus slide the leaf f downwardly against the resistance of the coiled spring f" and liberate the firing-pin (T, which then flies forward against the primer and explodes the cartridge.
The cartridge-case extractor consists of two upwardly-extending arms, JJ, provided with lateral pins or pivots i z", which project into openings in the inner surfaces of the walls of the breech. As the breech-block A is flush with or takes up the whole width of the breech-chamber, the sides of said block, along its bottom and front surfaces, have formed therein recesses JJ, which are of a depth inward from the sides of said block, equal to the width of the long or main portions of the extractor-arms JJ, sufficient room being provided at the upper ends of said recesses to permit the block to descend slightly along the extractor-arms previous to the commencement of its rotary movement. On the inner sides of the extractorarms, along their lower rearwardly-projecting ends, are formed curved projections i' i" , which extend into recesses or steps J formed along the lower front and bottom parts of the breech-block, and which are still deeper or cut farther in from the sides of said block than the recesses J. These deeper recesses or steps, when the breech-block descends to its revolving position, will bring their upper curved walls, 77, in contact with the curved projections i' i' on the inner sides of the extractor-arms. These upper walls, j j\ of the deeper recesses or steps J' J' are circular in form for a certain distance, as shown in Fig. 4, and are slightly eccentric with respect to the center of rotation of the block, so that during its rotation, as hereinafter described, said walls will press slightly and slowly against the curved projections i' i on the inner sides of the lower ends of the extractor-arms, and thus cause the heads i" i" of said arms (said heads being suitably fashioned to grasp the rim of cartridge-case) to move slowly to the rear and pull the shell along with them. At the rear ends, f f, of the deeper recesses or steps J' J' the upper walls, 77, change in curve abruptly downward ; hence these abrupt curves, coming in contact with the curved projections on the extractor arms, when the block has rotated sufficiently to the rear to fully expose the bore of the gun, will cause the extractor-heads i" i" to suddenly pull or jerk the cartridge-case and throw the same quickly to the rear.
Secured within the interior surfaces of the breech-walls, and suspended therefrom at the extreme rear of the breech, is a strong tray or support, L, which receives and sustains the weight of the breechblock when it is turned back and the bore is open for loading. As the cam E rotates rearward and the block A descends, the cocking-lug c"" of the firing-pin C takes against the bottom of the curved walled recess e' , formed in the middle of the upper rear part of said cam, and is moved rearward, the portion of the cam in front of said recess passing up into the curved front part of said cocking-lug. This pushing or retracting movement imparted to the firing-pin is effected against the resistance of the spiral spring D, which is contracted thereby, and said movement is continued until the circular recess e in the cam embraces the round shoulder 4 in the cavity, when the relative motions of the cam and firing-pin cease. When the recess e of the cam comes in contact with the round shoulder 4, the full-cock stud c'" of the firing-pin has passed the rear of the block and is caught by the sliding leaf F, before described.
Fig. 1 represents the breech of the gun as closed, or as it would appear after a discharge. To open the bore, the handle b is pulled to the rear, which turns the axial bolt B and the cam E. When the latter has been turned back a sufficient distance to cause its front point e" to pass out from beneath the wall 1 2 of the cavity in the breech-block, the toe e'" of said cam will press down upon the bottom wall of the cavity and force said block downward, this movement being permitted by the point e" of the cam moving along the inclined wall 2 3 of the cavity. After further turning the cam, accompanied by the downward movement of the block, its circular recess e embraces the rounded pin 4 in the cavity, and after this the further rotation of the cam is necessarily accompanied by the rotation of the block, which by this time has descended far enough for its axial bolt E to move to the upper part of the elongated opening 13, and for the bands to clear their grooves in the breech. After this, the movement of the block is rotary and to the rear around the axial bolt, it being guided by the cam-grooves 7 7 in its sides, and the guide-pins 1212. To close the gun, the handle b is turned forwards. At first the rounded shoulder 4 remains engaged in the circular recess e of the cam and causes the block to swing upward. In the meantime the guide-grooves in the sides of the block move over the pins or studs. On reaching point lo, in consequence of the change of the curves of the grooves, the upper surfaces or walls of said grooves take against the pins and are moved upward, thus forcing upward the breech-block and disengaging the rounded pin from the circular recess e of the cam. When this is effected, the front point e" of the cam commences to impinge at the point 3 in the cavity, and the rotary motion of the cam continuing, moves along beneath the inclined wall 2 3 in said cavity and forces the breech-block upward. In the meantime the guide-pins change position in the grooves, moving from points 9 to points 8 ; also, the axial bolt changes position from the top to the bottom of the elongated opening 13. When the point d' of the cam reaches the lower or front end of the inclined wall 2 3, it moves a short distance beyond the same and beneath the wall 1 2 in the cavity and firmly supports the breech-block in its raised and closed position. Further forward motion of the cam is prevented by coming against the face-plate 5, and by the catch on the handle.
In the 3- and 6-pounder the twist of rifling is that of a semi-cubical parabola. Theoretically, this curve produces less strain on the rotating band than any other, and less than a uniform curve.
The sighting of the guns is such as to admit of either quick rough sighting or very close fine sighting.
The sights, both front and rear, have rings one inch interior diameter each, through which the line of sight passes.
In the front ring there are single cross-wires, and in the rear sightring double cross-wires. For rough sighting it is sufficiently near to keep the rings concentric and the target in the center without regard to the wires. At the distance the front sight is from the rear one the front ring appears considerably smaller than the other (about one-quarter inch diameter) so that the eye will catch the position of center with a very small error. The advantage of the rings is that they give a clear view all around the target, and the motion of the platform and of the target can be anticipated and the sights kept on with little difficulty. With the sight-notch in a solid bar the target is only visible when it is above the line of sights, and motion of the ship or target cannot be anticipated.
When no other drill is provided the following is used:
DRILL OF THE 1-POUNDER, 3-POUNDER, AND 6-POUNDER DRIGGSSCHROEDER GUNS. (CREW OF 3 MEN.)
Nos. Stations. Arms, Revolvers.
1 1st Captain 1
2 2d Captain 1
3 Shell man 1
(Note.—The crews of the secondary battery are not assigned as boarders or riflemen.)
The exercise supposes the guns to be mounted in place and lashed, as well as clamped against elevation and train.
A gun's crew consists of three men, all of whom should be, as far as practicable, thoroughly trained rifle-shots.
The stations of the crew for mustering, when the gun is secured, are as follows : For guns mounted on deck—in line, directly in rear of the gun, facing inboard, No. 1 on the right ; for guns mounted aloft—on deck, abreast the mast, facing outboard, No. 1 on the right.
This is preparatory, and is given to secure attention to the following order:
CAST LOOSE AND PROVIDE.
1 commands; removes gun cover; casts adrift gun lashings; places sight cover clear ; ships gun stock ; tests breech mechanism ; examines bore ; sees in place gear and implements for the service of the gun ; for drill, puts on drill washers.* When all is ready, reports to officer in charge and takes station in rear of and facing gun.
If gun is mounted aloft, he first goes aloft and sends down tackle for hoisting up ammunition and other articles for the service of the gun ; receives articles whipped up by 2 and 3.
2 provides and examines the reserve box containing the accessories and spare parts;! provides three revolvers and belts, and puts revolvers in rack near the gun ; provides clean swab ; adjusts drill apron; sees trunnion and pivot clamps in working order; sees carriage in working order ; takes his station at left side of breech and facing it. If the gun is mounted aloft, he does not go aloft until all the articles for the service of the gun have been whipped up ; then secures net to top under lubber's hole.
3 provides swab and bucket of water ; brings ammunition from hatchway and places it in rear of gun amidships ; takes station alongside the ammunition. If gun is mounted aloft, assists 2.
After performing his duties, every one will put on his belt with revolver. After inspection by the division officer, and at his order "Lay aside belts and arvis," the belts and revolver will be removed and placed clear of the gun.
I places right shoulder to stock ; seizes the directing handle with left hand, and as soon as gun is undamped, lays it with muzzle outboard; plants feet firmly to resist motion of the ship.
2 assists 1; unclamps pivot and trunnion clamps as soon as 1 has his shoulder to the stock ; grasps with left hand and throws back smartly breech-block lever, opening breech ; takes cartridge from 3, points the shell fairly, and then enters it smartly in the gun and closes breech. Performs duties of 3 while the latter is providing fresh box of ammunition.
3 passes cartridges to 2.
1 steadies the gun with the right arm and shoulder ; adjusts sight, seizes pistol-grip, finger on trigger, and with his eye ranging over the sights, steadies the piece upon the object.
2 attends trunnion and pivot clamps. At a sliding pivot mount, adjust the position of pivot for train.
1 tends sight, rectifies aim and fires ; after reloading again rectifies
aim and fires, and so on.
2 tends clamps and loads.
3 supplies ammunition to 2, and in rapid firing stands by to relieve him; keeps empty cases clear of gun; when ammunition is nearly exhausted, provides a fresh supply.
1 removes his hand from pistol-grip, and steadies the gun until the pivot and trunnion clamps are tightened.
2 tightens trunnion and pivot clamps ; half-cocks.
2 grasps breech-block lever and draws it back easily with left hand, keeping right hand in rear of breech opening ; removes cartridge; passes it to 3 ; sponges bore if necessary ; closes breech.
1 eases firing-pin forward when breech is closed, then, assisted by 2, cleans and oils mechanism, if necessary.
3 receives cartridge from 2, replaces it in box, then closes box.
The numbers return what they provided, and secure what they cast loose, the gun having first been laid to the securing position.
DIRECTIONS FOR DISMOUNTING AND ASSEMBLING THE MECHANISM.
1-pounder, 3-pounder, 6-pounder Driggs-Schroeder on non-recoil stand.
No. 2 clamps the gun,
3 backs out right guide-bolt ; i raises rear end of stock ; 3 reenters guide-bolt (not far enough to engage in guide-groove) ; 1 lets stock down to rest on it. (If it is desired to take stock off entirely, 3 removes its pivot-bolt on the Y and takes it off.)
The breech being closed, 2 backs out left guide-bolt ; takes off operating handle ; taps end of axial-bolt to start it ; 1 holds block from underneath with left hand, and with right hand holds on to finger-catch of firing-pin ; 3 draws out main bolt, assists 1 to lower block out of place. The block being out, 1 full-cocks ; 3 removes face-plate; 1 uncocks by bearing down on sear arm, and then takes off finger-catch on rear end firing-pin ; 3 takes out firing-pin and spring; 1 takes out sear-plug, sear-spring and sear; 2 takes off sight, takes out extractors, removes pistol-grip, trigger, rock-shaft and tray.
Except in rare instances, such as dismounting for transportation or cleaning the sights, pistol-handle and tray should not be removed.
Proceed in the reverse way to dismounting ; firing-pin must be full-cocked before putting in face-plate, and let down to half-cock after face-plate is in place.
DETAIL NOTES UPON THE EXERCISE OF DRIGGS-SCHROEDER GUNS,
1. To secure to the crew the freedom of movement necessary to the efficient serving of the gun, arms and equipment should not be carried until required for use.
2. The number of rounds of ammunition to be brought to each gun as a first supply will be regulated by the commanding officer, and will depend upon the requirements at the time. In the absence of orders, a full box will be supplied.
During action the ammunition supply for R. F. guns is dependent mostly upon the rapidity with which it can be whipped up from below. It would be impossible to supply it as fast as it could be used in continuous rapid-firing. It will therefore be necessary to take advantage of all interruptions of fire to increase the supply at the gun, with a given whipping capacity ; the carrying from the hatches to the guns depends upon the distance and accessibility. One man, named conveniently Supply-man, assisted by No. 3 of each gun, can probably supply ammunition to four guns (two on a side) as fast as it is received from below. There may, therefore, be a Supply-man detailed for every four guns of the secondary battery. With Driggs-Schroeder guns, Nos. 1 and 2 can fire 12 to 15 shots a minute with No. 3 away.
3. In inserting the cartridge, 2 will keep it in mind to hold the rear end slightly raised with reference to the point, so as to avoid driving the point of the shell against the upper edge of the chamber.
The lower edge and sides are protected respectively by the breechblock and the extractors.
Neglect to observe the above precaution may result in a burr about the upper edge of the chamber.
While it is not necessary that the case should be pushed home against the extractors, it will be safer to send it well home. The extractors have a certain amount of yielding that will accommodate itself to any severity of ramming within reasonable limits.
4. If, after firing, the cartridge-case sticks after partial extraction, fully extract and then look for dirt or caked powder in the chamber. If such exists it must be removed with sponge if there is time.
5. If, in loading, a cartridge jam and will not let the breech-block close, never attempt to drive it home by forcing the block ; unload at once, put the cartridge aside and try another.
6. If the case does not extract, ram it out from the muzzle.
7. If one extractor breaks, the other will extract satisfactorily; but the first opportunity should be taken to put in a new one : back out the guide-bolts, half-cock, draw axial-bolt, holding the block by hand ; lower the block far enough to expose the extractor, resting the upper part on the tray for support; pull out the broken extractor and put in the new one. Do not put in the new extractor with a cartridge already in the gun, as the rib will come on the wrong side of the cartridge-head.
8. If the primer misses fire, full-cock again without removing block; in so doing the tension of the main-spring will indicate whether or not it is broken. If it feels stiff enough, but misses again, open and extract, put in new cartridge and try again. If it still misses, dismount the block, remove the face-plate and renew the firing-pin or spring, whichever is found defective. If the cap should have failed to obturate at any shot it is possible that a residuum may have been deposited on the front end of the firing-pin or rear face of face-plate, which might shorten the throw of the former and prevent it striking the cap.
9. In action do not try a second time any cartridge that has once failed unless it is absolutely necessary. To do so is an unnecessary experiment by which a telling shot may be missed.
10. In returning ammunition great care must be taken that empty cartridge-cases are not put in ammunition boxes containing loaded cartridges, and vice versa. 3 is held responsible for attention to this.
11. After ammunition boxes have been sent below, and before stowing them in the fixed ammunition rooms, the men stationed in the latter will redistribute the ammunition so as to completely fill all partially filled boxes but one. This last partially filled box should never be sent on deck in supplying.
12. The drill-washers are designed to prevent the firing-pin from delivering a sharp blow on the face-plate when snapping the gun at drill, and from delivering too strong a blow when drill cartridges are used. They should not be kept on when the piece is secured, as they increase slightly the compression of the spring when uncocked.
13. The drill apron is used only when the exercise is with drill cartridges.
14. Reserve boxes for 6-pounder, 3-pounder and 1-pounder contain the following accessories and spare parts:
Accessories—Sponge brushes, cleaning brush, oil can, screw-driver (special), clamping wrench, drill-washers.
Spare parts—Firing-pin, firing-springs, right and left extractors, sear, sear-springs, set of gun-screws.
15. In dismounting, the firing-pin must be uncocked before taking off the finger catch, otherwise the former would fly out with some force and possibly be lost.
16. In lowering the block, "tip the upper end slightly to the rear as soon as the bands are disengaged, and, holding on to finger-catch, lower block (forward of tray) in the hands of No. 3.
17. Lard oil should not be used on any part of the mechanism, as it hardens in cold weather. Mineral or fish oil is best.