UNITED STATES PACIFIC FLEET
AIR FORCE, PACIFIC FLEET
17 April 1944
From: Commander Air Force, Pacific Fleet.
To: Distribution List.
Subject: Basic Gunnery Doctrine and Instructions for Ships of Air Force, Pacific Fleet (Tentative).
Reference: (a) USF 10A, Article 6710.
1. Basic Gunnery Doctrine and Instructions for Ships of Air Force, Pacific Fleet (Tentative), as required by reference (a) is issued for use and guidance of ships of Air Force, Pacific Fleet.
2. All commands are invited to comment on subject doctrine and instructions and to submit recommended changes. Upon sufficient trial and incorporation of approved recommendations, this publication will be revised and issued to ships as Basic Gunnery Doctrine and Instructions for Ships of the Air Force, Pacific Fleet.
J. J. BALLENTINE,
CHIEF OF STAFF
GUNNERY DOCTRINE PART ONE
I. General Considerations.
(A) It is borne in mind that gunnery problems are affected by so many factors that a prescribed procedure may not be practicable under certain circumstance: Gunnery doctrine and instructions must therefore be flexible. However, sound doctrine or instructions should cover ordinary circumstances and may also serve in most extraordinary circumstances and this is the intent of this publication. Instructions and discussion contained herein are derived from a study of doctrine promulgated by other type commands, procedures used by experienced ships, conclusions and recommendations submitted in action reports, and the capabilities of weapons.
(B) The armament of ships of Air Force, Pacific Fleet consists primarily of defensive weapons. Discussion is therefore limited to factors which tend to promote the best defense against enemy attacks, with emphasis placed upon air attacks as those most likely to occur.
(C) Certain aspects of tactical and gunnery doctrine in repelling air attacks are listed in Part IV of USF 10A, which are not repeated hesein. Units will coordinate those considerations with type doctrine as circumstances require.
(D) Conditions of readiness for action are defined and requirements are prescribed in USF 10A, Part II. Requirements of conditions of readiness are amplified by Commander Air Force, Pacific Fleet confidential letter serial 0191 dated 18 January 1944.
(E) Doctrine and instructions contained herein cover the use of armament and fire control systems common to CV class carriers but pertinent parts are intended to also serve for other ships. Ships having 3" and 1.1" batteries should apply, as far as practicable, instructions concerning 5" and 40 mm batteries respectively.
II. Fire Power.
(A) The essentials of fire power are:
1. Accuracy with emphasis on early and continued hitting.
2. Rapidity with resultant high volume of fire.
(B) To obtain the above there must be:
1. Early sighting, recognition of target and readiness to fire.
2. Opening fire at earliest possible moment consistent with practical range of weapons.
3. Highest personnel skill, attained through training and indoctrination.
4. Thorough knowledge of capabilities of battery and fire control equipment.
5. Minimum of communications.
6. Simplicity of methods.
III. Selection of Targets.
(A) Sector organization.
A sector organization (4 sectors) for control of armament is recommended.
Sectors of 100 will give a slight overlap and this is desirable. The sector control method gives best assurance that all targets are taken under fire. Guns should be permitted to move from their assigned sector only when there definitely are no endangering targets in that sector. In this connection it should be kept in mind that in case of a rapidly maneuvering ship, targets will quickly shift from sector to sector.
(B) Preference of Targets.
1. Considering the capabilities of guns and danger of attacks, preference of targets is recommended as follows:
(a) 5"/38 caliber guns.
(1) Torpedo plane or skip bombing attacks.
(2) Dive or glide bomber attacks.
(3) High level attacks.
(b) 40 mm guns.
(1) Torpedo plane or skip bombing attacks.
(2) Dive or glide bomber or strafing attacks.
(3) High level attacks, if within range of guns.
(c) 20 mm guns.
(1) Dive or glide bomber or strafing attacks.
(2) Torpedo plane or skip bombing attacks.
2. The best target is the nearest plane threatening own ship. Planes which have completed their attacks or are retiring should not be fired upon if other threatening targets are available. Retiring planes should not be fired upon if own fighters are engaging them.
IV. Opening Fire.
(A) The responsibility for opening fire rests with the commanding officer. This authority should be delegated to proper subordinates in cases when the time factor is all important. All situations which may be met cannot readily be covered in a doctrine for opening fire but the following general provisions should be adhered to:
1. Enemy character of target normally must be determined before opening fire. This statement is qualified since methods of identification may not readily disclose the true identity of target, and the time factor is such that serious menace may be deemed to exist if fire is withheld pending further efforts of identification. An example of this would be if high speed aerial targets were to suddenly emerge from the sun or cloud concealment to threaten own ship. HERE THE ENEMY CHARACTER IS ASSUMED BY ITS ACTION, notwithstanding presence of own aircraft. In this case authority to open fire should be delegated to the gunnery control officer and others as required by armament characteristics.
2. When ample notice is given of an aerial target's approach, as in the case of prior detection; where the possibility exists of interference with other means of defense, such as fighters; and when the position of the ship in the formation is a factor, the responsibility of opening fire rests directly with the commanding officer.
3. When an enemy air attack develops, friendly fighter planes will, if possible, be vectored out to intercept attack. Ships shall exercise restraint in opening fire on enemy planes which are effectively attacked by our fighters. However, unless own fighter cover has the situation well in hand and no danger to own forces exist, targets should be taken under fire regardless of presence of own fighters, who will break off action when anti-aircraft fire becomes too dangerous.
4. Range of target must warrant opening fire.
5. Fire with automatic weapons may be opened only when the target is in sight except that 40 mm guns may be fired in radar control from their own or the 5" AA battery directors when the target is within self-destructive fuze action range and is attacking.
6. When operating in or near areas set aside as submarine sanctuaries or specified as operating areas for friendly submarines, personnel concerned must be kept fully informed. Outside of these restricted submarine areas, any submarine sighted will be fired upon immediately unless definite information or emergency identification indicates that it is friendly. Authority should be delegated to local gun stations to fire a few bursts at any submarine periscope sighted to indicate its position, except in restricted submarine areas. In all cases due caution shall be exercised to prevent firing on vessels in own screen.
7. During darkness the responsibility of opening fire rests with the commanding officer subject to orders of the Officer in Tactical Command. Here the question of opening fire will naturally be governed by best defense considerations with regard to desirability of concealment and also the danger involved from firing close to friendly ships.
V. Uses of Radar for Fire Control Purposes.
(A) Fire Control Radars.
The primary use of fire control radars is to provide early solution of the fire control problems. When the fire control radar is able to provide train and elevation as well as radar ranges, the director is said to be in Full Radar Control. Modified Radar Control is provided for surface targets where radar is used for train and range, elevations being provided by automatic level from the stable element. In case of low flying aircraft, modified radar control may be used with an arbitrary altitude setting. Full radar control (or modified) must be used when the target cannot be picked up with director optics. When the fire control radar provides only ranges and optics are used for train and elevation, (or with elevation in automatic level) the director is said to be in Partial Radar Control. Partial radar control is the primary method when it is possible to stay on the target using director optics.
(B) Search Radars.
Search radar information must be coordinated with fire control radars to obtain early solution of the fire control problem. In order to accomplish this, target designation must be promptly transmitted from search radars to fire control stations to permit early target tracking. Under certain circumstances spotting of fall of shot with search radars may be of considerable importance.
(C) Ranging by Radar.
Fire control radar ranges, when available should normally be used in preference to optical ranges since radar ranges are more reliable at battle ranges. However, optical ranges should parallel the radar in ranging to minimize interruptions in the event of radar casualty.
(D) Pointing and Training by Radar.
Pointing and training the AA director on air targets by radar alone (full radar control) is not as accurate and is much more difficult than keeping on a target with optics (partial radar control). Optics should be used for pointing and training where possible. However, it is absolutely essential that director crews be thoroughly trained in full radar control to permit accurate fire during low visibility. Ships, therefore, shall take full advantage of opportunities afforded in tracking own planes using full radar control and checking against optics, and also, using full radar control when appropriate target practice can be held.
(E) Illumination Control.
Radars should be used as the primary means of directing illumination either by star-shell, searchlight or both. Directors under full radar control should be placed on the target prior to the order "Illuminate". Ranges and bearings from search radars should be used to initiate illumination where fire control information is not available.
(A) The possibility of searchlight illumination of a target by ships of Air Force, Pacific Fleet is very remote. If very unusual circumstances render advisable the use of searchlights, shutters should remain open only long enough to observe the minimum required fall of shot, and fire should always be opened prior to or simultaneously with the opening of shutters.
(B) The use of star-shells for illumination of targets is discussed under Standard Fire Control Procedures. The prime essentials of good star-shell illumination are correct deflection and burst of star well beyond target.
Rapid and positive identification of the enemy or friendly character of a contact is of the utmost importance. To this end, sufficient personnel thoroughly trained in the identifying characteristics of ships and aircraft must be always available in case of contacts; appropriate personnel must always know the emergency identification signals in effect and ensure that immediate action is taken when required. Since a challenge may provoke gun fire, guns of own ship shall always be trained and pointed on target and ready to fire before making the challenge.
(A) Standard fire control procedures herein prescribed should produce the desired results under normal conditions when used by well trained and efficient fire control parties. Particular circumstances may render departures advisable, but considered judgment should be exercised in such departures.
(B) Brief procedures, only, are listed covering general set-ups. Ships necessarily will need to amplify procedures to ensure that all details are covered.
(C) Standard commands shall be used at all times. Proper interior communications discipline is absolutely necessary for good control of battery.
(D) Types of air attacks for which procedures are prescribed are:
1. Horizontal Bomber Attack,
2. Dive Bomber Attack, and,
3. Torpedo Plane Attack.
The defense against glide bombing, skip bombing, strafing or suicide plane attacks will be similar to that employed against one of the three main type of attacks, depending upon manner of approach.
IX. Control of Gun Fire - 5"/38 caliber battery.
1. Open fire in accordance with instructions in Section IV. Maximum surface range of gun is about 18,000 yards. Consistent with open fire doctrine it is considered that, against air attack, the maximum slant range will be about 10,000 yards, if own fighters are present, In case of enemy torpedo planes being effectively engaged by own fighters, antiaircraft fire should be withheld somewhat longer but in no case at ranges less than 6,000 yards. Range of opening fire at night is subject to modification by Officer in Tactical Command, and this will largely depend upon light conditions.
2. The use of Mark 32 fuzed projectiles introduces factors which influence the choice of a fire control method. Authorized personnel should thoroughly understand the features of this type projectile, discussed in separate correspondence, and analyze the conditions under which its use is most beneficial. The use of this projectile will be discussed further under separate correspondence.
3. The principal methods of control with Mark 37 Director and Mark 1 Computer resolve themselves essentially to 3 in number:
(a) Using full advantage of tracking.
(b) Using a "Dive Attack" set up.
(c) Using barrage fire.
The first method, tracking with guns, director and computer in automatic should be used when practicable. However, with high speed or multiple targets it is generally necessary to use the second or third method. The "Dive Attack" sot up should give best results when target is directly approaching own ship. When the approach is not directly toward own ship, deflection is introduced and at close range large spots may be necessary when using a "Dive Attack" set up. If considerable deflection is introduced, a barrage fire will normally be more effective.
4. Procedures described consider one director and the guns it controls. However, in sector organization, divided fire may result and, also, primary and secondary methods of control may occur simultaneously depending upon number and bearings of attacks.
5. In double or multiple ship concentration of fire, spotting will be very difficult. It may be possible to follow tracers to bursts to aid in spotting, but too much success in this connection cannot be expected. 6. Although surface action is far less probable than air action, ships must be prepared to use their weapons against surface craft, and therefore approved procedures are prescribed herein.
(B) Air Action - Horizontal Bombers.
1. Director Control.
(a) Director, and guns in automatic. Direct range keeping in automatic or semi-automatic rate control with partial radar control.
If target is not visible in optics, director should commence tracking in full radar control. Designation from search radar may be necessary. Continue in full radar control until optics can be used for partial radar control.
(b) Continuous aim.
(c) Salvo fire preferred (continuous fire optional)
(d) Salvo fire interval 4 seconds (or smallest considering state of training.
(e) Use two spotters:
One spotter control in range, other spotter control in elevation and deflection.
1. Follow as closely as possible Primary Method depending upon casualties encountered. One of the following types of barrages may be used.
(a) Director controlled fixed zone barrage.
(b) Local controlled fixed zone barrage using open sight or telescope aim.
(C) Air Action - Dive Bombing Attacks.
1. Dive bombers observed approaching formation before commencing dive shall be fired upon as for Horizontal Bombers.
2. Primary Method of control after diving.
(a) As first plane commences to dive, shift to director controlled "Dive Attack" set-up.
(b) When target is within effective range of automatics shift to next following target.
3. Alternate Primary Method.
(a) As first plane" commences to dive, shift to director controlled fixed zone barrage.
(b) A normal fuze setting for barrage range of 1600-2300 yards (2-3 seconds) should be used. The lower setting is recommended only when cloud ceiling or "peel off" altitude is low. Automatic weapons prove to be much more effective within 2000 yards and low 5" bursts may interfere with the aim of the automatics.
(c) When target comes through barrage, shift to next following target.
4. Secondary Methods.
(a) Control individual guns by heavy machine gun directors, using barrage fire (2-3 seconds) fuze setting subject to same remarks as for alternate primary method.
(b) Local control fixed zone barrage.
(1) Use open ring sight, if installed.
(2) Fuze setting (2-3 seconds),
NOTE: Considering the relative ineffectiveness of 5" guns in local control against dive bombers, it may be advisable to refrain from using them in this connection, if fire of automatic weapons is aided thereby.
(D) Air Action - Torpedo Plans Attacks.
1. In a case of a single plane attack or whan ample time exists between single plane attacks to obtain separate solutions, the primary method of tracking as proscribed for horizontal bombers should be used. Except at night, however, single plane attacks are unlikely and the method described in the following paragraph is preferred against multiple plane attacks.
2. Primary Method.
(a) Use closest plane as target,
(b) Use director control "Dive Attack" set-up.
(c) Use super-elevation correction on the director as a range spot in an attempt to bring bursts about 20 feet above plane,
(d) The lowest fuze setting to use will depend upon distance of screen and closeness of ships of screen to line of fire,
Tho lowest fuze setting normally should be 3 seconds (2300 yards) at which time shift should ho made to next approaching target,
(e) As target closes, deflection may be a problem in this set-up due to its angle of lead, and spots may be necessary.
3. Secondary Methods (order of preference).
(a) Director controlled fixed zone barrage using two fuze settings-5 second setting until target passes through barrage and then a 3 second fuze setting. Super-elevation correction should be used to place bursts about 20 feet above target. As target passes through inner barrage shift to next approaching target,
(b) Control individual guns or groups with heavy machine gun directors using fixed zone barrage fire with 5 seconds followed by 3 seconds fuze settings,
(c) local control using fixed zone barrage fire with two fuze settings - 5 seconds fuze setting followed by 3 seconds fuze setting.
NOTE: Barrage fuze settings may have to be modified if screen is endangered by above settings.
(E) Night Torpedo Attack.
1. The following summary of anti-aircraft defense against night torpedo attack quoted from Pacific Fleet Gunnery Bulletin No. 3-44, is considered an excellent procedure and is therefore incorporated in those instructions:
Set target speed
Set mean of 170 knots on computer until solution is obtained.
Set target altitude (after range has decreased to 6,000 yards).
Use dip dial, rate of climb knob or other method of controlling estimated altitude when target is hot in sight and too low for accurate elevation tracking.
Ratio Mk. 32 Fuzes
50ˇ-75% (If target is very low use the lower ratio).
Open fire Range
10,000 yds. After computer has good solution.
Two essentials in this problem are:
(a) Rapid transfer from search to fire control radars.
(b) Ability of director operators to track and stay on target even during maneuvers. This skill can be acquired only by ceaseless training of operators both aboard ship and at radar schools, which director crews should attend quarterly, if possible.
2. The arbitrary altitude settings in the above procedure are based upon inaccurate radar elevation tracking when the position angle of target is very low and the range is less than 6,000 yards. At ranges greater than 6,000 yards, it is considered that elevation tracking with Mark 4 Radar will be reasonably accurate with a mild sea running and experienced operators. If this is not the case, arbitrary altitude settings are also recommended for ranges in excess of 6,000 yards.
(F) Day Surface Action - Medium Range (less than 8,500 yards).
1. Director Control.
(a) Direct range keeping with director in partial radar control (continuous radar ranging).
(b) Salvo fire (master key)
(c) Salvo interval 4 seconds (or smallest considering state of training).
(d) Continuous aim (if sea is too rough for continuous aim, use selected level).
(e) Use automatic level (pointer position radar for best response, dip dials matched with advance range on computer).
2. Spot direct. (use of a continuous "rocking" ladder covering range band 100 yards on each side of best radar range is optional).
3. Shift way be made to rapid continuous fire when target has been definitely located within small limits.
4. When using Optical Ranges.
(a) Open fire with down ranging ladders of 3 salvos, ladder increments 300 yards.
(1) Fire first salvo using best range plus 300 yards.
(2) Second salvo best range.
(3) Third salvo best range minus 300 yards.
(b) After firing the down ranging ladder commence a 100 yard step continuous ladder from best range, initially down, covering range band 200 yards on each side of best range.
(c) After spotter observes ranging salvos and target has been located, shift may be made to Rapid Continuous Fire, and continuous ladder 100 yards on each side of best range, changing range at 3 second intervals.
(d) At ranges less than 3,000 yards, no ladder is required.
(G) Day Surface Action - Long Range (over 3,500 yards).
1. Same as for medium range except:
(a) Use salvo fire throughout.
(b) Double the increments of all ladders.
(c) At extreme ranges, after spread is fired, a ladder should be run for two steps on each side of best range.
(H) Night Surface Action.
1. Director Control.
(a) Direct range keeping with director in modified radar control until illumination permits use of partial radar control.
(b) Salvo Fire.
(c) Salvo interval 4 seconds (or smallest considering state of training).
(d) Use automatic level with dip dials matching advanced range.
2. Illumination as ordered by Officer in Tactical Command.
3. Open fire with a continuous ladder, size of steps 200 yards.
(a) Fire first salvo with best radar range, second salvo down 200 yards from best range, third salvo at best range, fourth salvo up 200 yards from best range, fifth salvo at best range.
(b) Continue in a band of 200 yards both sides of best radar range using a continuous ladder, initially down, steps 100 yards, back and forth across the target.
(c) If continuous ladder does not bracket the target, apply a direct spot to center continuous ladder on target. As soon as direct spot is applied, resume continuous ladder.
4. When the director is in modified radar control the trainer will automatically cause a slight deflection spread by the inherent errors in matching pips.
5. When using estimated or optical ranges:
(a) Open fire with a. down ladder with steps of 500 yards each.
(b) Fire first salvo using best range plus 500 yards. Continue down ladder until shorts are observed.
(c) After target has been located and crossed by down ladder, start a spotter controlled ladder from the nearest ranging salvo in steps of 200 yards.
(d) If first salvo is observed to be short, start a spotter controlled continuous ladder from this salvo, in steps of 500 yards until target is crossed, on reversing ladder reduce stepsto 200 yards.
6. Shift may be made to rapid continuous fire when target has been located definitely within small limits; For rapid continuous fire change range 100 yards every 3 seconds, following ladder plan of 3(b) above.
(I) Night Surface Action - Illumination.
(a) If the fire control problems can be solved by radar alone, fire should be opened prior to illumination and with flashless powder so that the element of surprise may be exploited to the fullest extent.
(b) When fire has been opened by modified full radar without prior illumination one or two guns may be used to provide starshell illumination, if fall of shot cannot be observed by radar.
(c) If only search radar is available it should be used for firing star÷shell search spreads.
2. Star-shell Search Spread (Fired when target has not been accurately located).
(a) Director controlled.
(b) Units of divergence between guns - 2ˇ.
(c) Use fuze setting and gun elevation to cause starshells to burst:
(1) At an altitude of 1,500 feet.
(2) At a horizontal range of not less than 10,000 yards, if visibility is good or at least 2,000 yards beyond range of most distant target.
(d) Fire three salvos with center of salvos as follows:
(1) On the General Bearing line.
(2) 5ˇ left of the General Bearing Line.
(3) 5ˇ right of the General Bearing Line.
(e) Use flashless powder.
3. Single Star-shells.
(a) Use fuze setting and sight bar range so star÷shells will burst 1,500 to 2,000 yards beyond target and at an altitude of 1,500 feet, (b) Use flashless powder.
4. Searchlights. Primary Method.
(a) Director Control.
(1) Full Automatic.
(b) When ordered, strike arcs with shutters closed.
(c) Open shutters when ordered to illuminate.
(J) Surface Action - Secondary Methods.
1. Follow as closely as possible Primary Methods.
2. Shift to local control as a last resort.
3. As method of control becomes more elementary the most simple procedures are necessary.
4. Every effort should be made to set uniform ranges and deflections on all guns firing and to spot from one station as long as possible.
5. In elementary methods of control ranging ladders with large increments will be found necessary. When target is definitely crossed, ladder should be halved and reversed. In case of a target rapidly closing in range a barrage fire will be the most simple. In this, the gun range should be dropped to a new setting, as target passes through the barrage.
X. Control of Gun Fire - Automatic Weapons.
1. Discussion of the control of automatic weapons is considered necessary on account of wide differences in existing practice concerning the control of these weapons particularly in regard to range of opening fire and the range setting procedure.
2. (a) The following two governing factors should determine the best range to open fire to obtain maximum results:
(1) longest time possible to have target under fire within practical range of gun.
(2) Maximum volume of fire when target is within effective range of gun.
(b) One factor may necessarily affect the other so that a balance between the two may be necessary to obtain the best opening range.
(c) Effective range of automatic weapons is not rigidly defined but it is generally assumed to be the maximum range within which the trajectory is relatively flat and hitting is probable with good gun laying.
3. Primary method of control for 40 mm mounts is by director; for 20 mm guns, the Mark 14 Sight.
(B) Control of 40 mm Fire.
1. Range of opening fire.
The 40 mm H.E. projectile has a self-destructive feature wherein tracer burn-out causes fuze action at approximately 4,000 yards. (Present lots include projectiles with fuze action at about 4,400 yards). Therefore, beyond the range of fuze action, there is no expectation of materially affecting a target by 40 mm gun fire. The effective range of this gun is generally assumed to be about 2000 yards. However, beyond this range, hits can be expected and may be obtained up to the limit of the range of fuze action. Consequently, as a rule, it is considered that there is no advantage in withholding fire when the advance range of target is within fuze action range of projectiles. The quantity of 40 mm ready service ammunition available and the manner of loading should permit a constant volume of fire throughout the approach, even if fire is opened at range in excess of 4,000 yards. Multiple targets closely approaching in successive attacks will naturally force a departure from a definite opening range, but this does not alter the question of what is the best opening range. If fire
is opened at a range in excess of 4,000 yards an appropriate range spot should, initially, De introduced in Mark 51 Director.
2. Range Setting Procedure.
A correct range setting throughout approach of target under fire should give the best results. When radar range settings can automatically be introduced, this problem is solved, but in only a few of the present installations, can this be accomplished. In practice it is found that an initial range setting may be obtained and transmitted to mounts or directors but that, thereafter, ranging must be done locally. Ranges obtained locally, either by estimate or through a range finding device, will be. approximate, only. The usual practice is to set ranges through observation of the tracer stream. With the range setting less than the actual range, the tracer stream will be seen below the target and, as target comes closer, the tracer stream will pass through and then above target. Theoretically, best results would be obtained if the range were reduced gradually as the tracer stream passed through target, in an effort to keep tracer stream at that point. Practically, it is not believed that this can be done. The spotter (range setter) cannot be assumed capable of discerning the tracer stream actually passing through target, inasmuch as the primary reason for the development of the Mark 14 Sight is based upon an individual's lack of stereoscopic vision ability except at very short ranges. The extent of a spotter's ability is to tell when the tracer stream has definitely passed through the target and is missing above. Now, with a fast, directly approaching target (180 knots) the rate of change of range is 100 yards per second. In this case it is considered advisable to decrease the range setting in 800 yard increments, as 400 yard steps will scarcely allow sufficient time for tracking at a new range setting before the tracer stream is again passing above target.
(C) Control of 20 mm Gun Fire.
1. Range of opening fire.
It is considered absolutely essential that maximum volume of 20 mm fire be realized when the target is within effective range of the gun. The maximum effective range may be assumed to be 1200-1500 yards. Therefore, it is most desirable that changing of magazines be not required at this range and if possible not until target has approached within 800 yards, at which range it is expected that target will have dropped torpedo or bombs, if carrying either. However, it is also desirable to take a target under fire for as long as possible within reasonable limits of range, before the bomb or torpedo dropping point is reached. Consequently, in case of 20 mm guns, it is necessary to seek a compromise between these two conflicting factors. It requires 7 1/2 seconds to empty a sixty (60) cartridge magazine. A longer period is normally required due to firing in bursts and a safe minimum average may be said to be 10 seconds. Now, if fire is opened at 2,000 yards, advance range of target will be 1,700 yards range or less, and should be well inside 1,000 yards when the last projectile of an average magazine is fired. To better ensure this, if all 20 mm guns which can bear, open fire at once, an opening range of 1,600 yards is preferable. There is, however, a strong desirability that all or most of 20 mm magazines not be changed at the same time and therefore, a better plan is to open fire with half of the guns at one range and with the other half at a range a few hundred yards less. The desirable opening range for half of the guns would be
2,000 yards, and for the other half 1,600. When a gun is manned by gun layer only, an opening range of 1,600 yards is considered best practice.
2. Range Setting Procedure.
Remarks made in regard to 40 mm range settings, in general, apply likewise to 20 mm guns with Mark 14 Sights. For a fast approaching target decrease in range settings in 800 yard increments is recommended if initial range setting is 1,600 yards or more. When a gun is manned by gun layer only, a single range setting of 1,200 yards is recommended.
3. Fire Discipline.
A most difficult feature of control of 20 mm guns is that of fire discipline. If other guns are firing, communications may become inefficient, and the firing of 40 mm guns tend to cause a sympathetic reaction resulting in premature firing of 20 mm guns by personnel. Every effort must be made to guard against opening fire too early with 20 mm batteries. Likewise, it is most important that effective means be devised to stop 20 mm firing when the order "Cease Firing" is given.
4. Range finding and estimations.
The maximum use of range indicating devices furnished ships is encouraged. These devices usually require plane identification to obtain width of wing span, and, therefore, ability to identify aircraft is important for this reason alone. Range estimations should be practiced and checked by range finder as much as possible. It appears that the prevailing tendency is to underestimate ranges, particularly in moments of excitement, and this should be remembered. If 20 mm fire is opened too early, the only remedy is changing magazines as quickly as possible.
(D) Summary of Recommended Control Procedure,
1. 40 mm mounts.
(a) Best advance range to open fire - 4,000 yards (may be increased to 4,400 yds. if fuze action of projectile is at this range),
(b) Set maximum range on directors (3,200 yards). Apply range spot if present range is in excess of 4,000 yards.
(c) Decrease range settings when target has definitely passed through tracer stream, in 800 yard increments.
(d) Use radar ranges if so equipped, when practicable, in lieu of steps outlined in (b) and (c).
2. 20 mm Guns with Mark 14 Sights.
(a) Two ranges of opening fire.
(1) Half of guns which bear open fire at range of 2,000 yards. Set range of 1,600 yards on sight. Drop range to 800 yards when target has definitely passed through tracer stream.
(2) Other half of guns open fire at range of 1,600 yards. Set range of 1,200 yards on sight. Drop range in 400 yard increments as target passes through tracer stream.
(b) All guns which bear opening fire at same range.
(1) Open fire at range of 1,800 - 2,000 yards.
(2) Set range of 1,600 yards on sight.
(3) Drop range to 800 yards when target has definitely passed through tracer stream.
(c) Any gun manned by gun layer only, open fire at range of 1,600 yards with single range setting of 1,200 yards.
(d) Use every effort to enforce fire discipline.
(e) By training, obtain the irreducible minimum time required in changing of magazines.
(f) Avoid opening fire too early.
(E) Fire of Automatic Weapons on Surface Craft.
1. No procedure is set forth covering fire of automatic weapons against enemy surface craft. When such targets are within range of guns, automatic weapon fire directed against superstructure installations and exposed personnel should be very damaging.
XI. Training Instructions.
(A) Anti-aircraft training instructions and suggestions are treated at length in various publications and in Fleet and Type correspondence. It is noted that ships, in most cases, have prepared excellent training instructions pertinent to their respective ordnance installations. It is desired to emphasize the importance of a few considerations of training which are briefly discussed below:
1. Condition Watch Training.
Training of personnel during condition watches assumes major importance in wartime. It is not practicable to hold frequent and lengthy drills with all batteries completely manned without introducing undue hardships on personnel. Most of the training required to correct deficiencies, therefore, must and should be done during condition watches. To the extent practicable, it is desirable that condition watch personnel be assigned their General Quarters stations. Progressive training in gunnery essentials, properly conducted, should be a definite part of each condition watch.
2. Observation and Correction of Individual Performance.
It is considered that few ships pay sufficient attention to individual performance. If an individual whose station is on a 5" director or computer commits an error, it will usually be quickly apparent, since his error may affect the fire of an entire 5" battery. To a lesser degree, the same thing may be said of an error made by a member of a 5" loading crew, placing his mount out of commission. If these errors are not detected at the time, the results are such as to prompt a later investigation and corrective action. Proper attention to and application of correct procedures are essential to the successful performance of a 5" battery, but because of its characteristics, an individual's performance docs not long go unnoticed. This is not necessarily the case with the fire of automatic weapons. There are many automatic weapons on a ship, each, as a rule, controlled locally. The performance of any one or more of these weapons may be, and usually is, lost sight of in a firing which is viewed collectively from a distant station. If such is the case, obviously a change in training methods should be indicated, since efficiency cannot readily be improved, if existing faults are not known. It is, therefore, strongly urged that ships give every attention to qualified observation of individual performance on automatic weapons, as a most important step toward increasing the effectiveness of these weapons.
3. Training Courses and Aids.
Every opportunity should be taken of training courses and aids available at shore activities and on board ship. For convenience, several training courses and aids available in the Hawaiian Area era listed herein, and certain similar facilities are available in other Pacific Ocean Areas:
(a) A.A. Training Center, Waianae, Oahu, T.H. - Courses offered include a two-weeks complete course in use of automatic weapons and a one-day refresher firing course. When time permits, ships in Pearl Harbor are urged to obtain a quota for two-weeks course.
(b) Facilities at Bloch Recreation Center, Pearl Harbor, Oahu, T.H. including:
(1) Night Lookout Trainer.
(2) Night Vision Testing.
(3) 5"/38 caliber and 3"/50 caliber loading machines.
(c) Camp Catlin, Oahu, T.H. facilities including:
(1) Fleet Gunnery and Torpedo School. A limited quota for officers may be obtained for a four-weeks course in 5"/38 caliber and a three-weeks course in 3"/50 caliber guns and their respective fire control systems.
(2) Short course (three-four days) in fire control radar for Mark 37 Director crews.
(3) Demonstration of CIC in operation.
(4) Spotting Board for control officers and ships' spotters.
(d) Installation of special devices in connection with training in the use of automatic weapons, at the Naval Air Station, Oahu, T.H. is contemplated in the near future. These devices will include a Mark 3-A-2 Trainer with anti-aircraft film to be used in conjunction with the Mark 51 Director or 20 mm mount and Mark 14 Sight, Smooth tracking ability, so essential in the use of the Mark 14 Sight, is greatly facilitated by the use of this training aid. Insta
lla tion of this equipment is authorized for aircraft carriers, and it is recommended that each carrier obtain and install necessary equipment at first opportunity. The Gunnery and Training Division of Commander Air Force, Pacific Fleet, will assist ships in Pearl Harbor in this installation.
BuOrd BULLETIN OF INFORMATION 1-45 of March 31st 1945.
PARAGRAPHS 55 to 57 Inclusive and 67.
Rate of Fire of 40mnm AA Guns. Action reports occasionally state that at high angles of elevation the performance of 40mm AA guns has appeared to be sluggish. The results of tests conducted recently to determine how much the cyclic rate of fire is reduced at high angles of gun elevation indicate that with an increase from 0ˇ to 70ˇ, regardless of the rate of fire at 0ˇ this rate is decreased by approximately 20 rounds per minute. The following tabulation contains the results of these tests:
Rate of Fire (Rounds Per Minute)
The Bureau is informed that a great many, if actually not most, 40mm machine gun mechanisms in service have been set, by adjusting the needle valve of the recoil cylinder, to fire at a rate that first loaders of average skill can maintain that this rate is frequently 120 or even as low as 100 rounds a minute. Attention is invited to OP 820 (Prelim.), Chapter 1 (introduction), which states that the 40mm AAG is capable of a maximum cyclic rate of fire of approximately 160 rounds per minute. It is noted that if the rates of fire are set as low as 120-100 rounds per minute at 0ˇ gun elevation, the rates at high angles of elevation may be undesirably low, especially when these guns are used to counter suicide bomber attacks.
Therefore, it is recommended that the needle valve be set wide open at all times except in certain target practices where for reasons of economy of ammunition a lower rate may be acceptable. Only in this way may the full capabilities of this well-proven weapon be realized. First loaders must be trained to keep up with the maximum rate of which the mechanism is capable.
FOR 20MM GUNS
The present accepted policy is to set range of all gun sights at 1200 yds. and leave it there - and all guns open fire when target is at an estimated range of 1500 to 1600 yds.
April 24, 1945
FIRING DOCTRINE FOR MK 14 MOD 6 - 20MM - GUN SIGHTS
1. On manning gun stations see that "Procedure for manning MK 14 sight" has been carried out.
2. When cocking gun set range at 2000 yards.
3. When slewing to pick up target set range at 400.
4. When securing sight, set range at 400 yards.
5. Firing will be in short bursts to assist gunner in keeping target centered.
Firing on approaching targets: - "Open Fire" range will vary from 1500 to 1600 yards.
1. Set 1200 yard range on sight (after picking up target).
2. "Commence fire" wiil be given by control to the Bank officer over sound power telephone.