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Chapter 5 Elements of Gun Mounts
A. Introduction
B. Features of modern naval guns and mounts
C. Conclusion
                                                        C. Conclusion

5C1. General

The preceding section provided an overview of the 10 major features or characteristics which distinguish the modern gun from its predecessors. As the discussion has pointed out several times, not all of these features will be found in all modem guns-particularly in small arms and machine guns. And considerable variations in details of design from one mark and mod of weapon to another. But the features described are those that are referred to elsewhere in this book as “conventional,” meaning that they represent standard practice in the art of gun and mount design as it exists in the United States Navy about the middle of the 20th century. New developments and improvements in guns and mounts are, of course, always in progress. Many of these are taken up later in this series of textbooks-particularly in chapter 32, volume 3. Further details of these “conventional” features, as they pertain to specific guns and mounts, are in later chapters concerned with the different main types used in the Fleet.

5C2. Review of definitions

Following is a brief list of definitions which summarize in general form some key terms used in the preceding section.

Gun. The term gun properly designates the tube or barrel, but is commonly used to refer to the whole assembly of which the barrel is but a part.

Mount. This is the entire system between the gun and the ship’s structure which supports the gun, secures it to the ship’s structure, and provides for its elevation, train, and (in guns larger than 20-mm) recoil and counterrecoil. There are several types of mounts, but all of them must accomplish these functions. Larger mounts have other functions as well.

Train. The train of a gun is the position of the axis of the gun’s bore in azimuth (or in a plane parallel to the deck), as measured from the ship’s centerline. Training the gun is rotating it in azimuth. The trainer is the person who controls the training of the gun. The training gear is the equipment used to train the gun.

Elevation. The elevation of a gun is the angle that the gun bore axis makes with the deck, measured perpendicular to the deck. Elevating the gun is increasing this angle; depressing the gun is decreasing this angle. The elevating gear is the equipment used to move the gun in elevation. The term pointing has the same meaning as the terms elevating and depressing combined. The pointer is the person who controls the elevation or pointing of the gun.

Recoil. Recoil is the force tending to push the gun to the rear as the projectile is discharged. It is the gun’s reaction to firing. Recoil is also the rearward movement of the gun. The recoil mechanism is the equipment used to control the gun recoil. Recoiling parts are those that move with the gun in recoil and counterrecoil.

Counterrecoil. Counterrecoil is the forward movement of the gun after recoil which returns the gun to its original firing position. The counterrecoil mechanism (also known as the recuperator) is the equipment that returns the gun to its firing position.

In battery. A gun in its firing position as regards recoil and counterrecoil is said to be in battery. A gun moves out of battery during recoil and returns to battery during counterrecoil. Recoil position is the rearmost position of the recoiling parts in recoil movement.

Housing. The housing of a gun is a generally box-shaped structure joined to the gun barrel with a bayonet-type joint. On most intermediate-caliber guns it houses the breech mechanism. Since it is attached to the gun barrel, it is a recoiling part. Major-caliber bag guns have no housing; these have yokes, which, in general, perform a similar function. (See art. 7B1.)

Slide. On all guns larger than 20-mm, the slide is the structural part which supports the gun, housing, and other recoiling parts, and permits them to move in recoil. The slide will be discussed further in the next section, where it is taken up as part of the mount.

Automatic guns. Automatic guns are case guns in which some of the energy of the propellent explosion is used to open the breach, eject the empty case, and operate the device which automatically loads another round of ammunition. The gun can continue to fire so long as ammunition is supplied and the trigger is operated.

Semiautomatic guns. Semiautomatic guns are case guns in which some of the energy of the propellent explosion is used to open the breech, eject the empty case, and automatically close the breech when another round is loaded. Semiautomatic guns, unlike automatic guns, must be loaded either by hand or by auxiliary equipment.

Nonautomatic guns. Nonautomatic guns are those in which none of the energy of the propellant is used to perform breech opening, closing, or loading functions. All bag guns are of this type.

Rapid-fire guns. Rapid-fire (RF) guns are those in which loading, firing, empty-case ejection, and breech operation are performed automatically but are powered by a source of energy other than the propelling charge.

Axis of bore. The axis of the bore is a straight line passing through the center of the gun bore.

5C3. Designation of guns by caliber

The caliber of a gun (the diameter of its bore measured to the tops of the lands) is expressed in inches or millimeters. For all guns of caliber 3-inch and above, the length of the gun barrel is customarily expressed by dividing the length of the bore plus the length of the chamber by the diameter of the bore. Thus a 3”/50 caliber gun barrel has a caliber of 3 inches and is 50 calibers or 150 inches long. Guns of calibers less than 3 inches are not usually spoken of as being so many calibers long.

Guns are usually designated by (1) their caliber in inches, followed by the length of the gun in calibers and by mark and modification numbers, or by (2) the diameter of the gun is millimeters followed by the mark and modification numbers. Thus there are 16-inch 50-caliber Guns Mark 1 Mod 1, and 40-millimeter Guns Mark 1, Mod 1.

Guns are classified according to bore diameter:

1. Major-caliber---8 inches or larger.

2. Intermediate-caliber--greater than 4 and less than 8 inches.

3. Minor-caliber-greater than 0.60 inch but not more than 4 inches.

4. Small arms-O.60 inch or smaller.

5C4. Guns in service

Guns most likely to be found on Navy ships today are:

    Guns              Carried on

16”/50 cal.......... Battleships
16”/45 cal.......... Same
12”/50 cal...........Large Cruisers
8”/55 cal.............Heavy Cruisers
6”/47 cal.............Light Cruisers
5”/54 cal.............Large carriers, destroyers, and frigates
5”/38 cal.............Battleships, cruisers, destroyers, carriers, and auxiliaries
5”/25 cal.............Submarines
3”/50 cal.............Any ship from patrol craft to battleship
40-mm...............Any ship from patrol craft to battleship
20-mm...............Any ship from patrol craft to battleship