Browning Gun .303

Browning Gun .303

A detailed manual on a Browning Gun. There are instructions and sketches on the stripping of the gun.

20 printed sheets

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MAnkersonR[Ser#-DoB]-180129-04

BROWNING GUN

.303

[underlined] NAMES OF PARTS [/underlined]

[inserted] RUABTEECAB 1140 [indecipherable word] [/inserted]

1. The following descriptions of parts gives the names and uses of the different components falling under each group. Where the symbol (F) follows a name it denotes that it is not in itself a gun component, but simply a feature of a main group. Such features are formed either by machining, or by permanent fixing to main component by riveting, etc.

[inserted] [circled R]ecoil
[circled U]nlocking
[circled A]cceleration
[circled B]ackward out of the block
[circled T]ransporter
[circled E]xtraction
[circled E]jection
[circled C]ocking action
Action of [circled B]elt feed [/inserted]

[underlined] RECOILING PORTIONS: [/underlined]

[underlined] BARREL GROUP:- [/underlined] (a) Locking notches. (F)
(b) Ejector top clearances. (F)
(c) Ejector side clearances. (F)
(d) Tang. (F)
(e) Boss. (F)
(f) Barrel extension stud. (F)
(g) Barrel locking spring.
(h) Locking piece
(i) Locking piece pin.
(j) Locking piece cam grooves. (F)
(k) Clearance for trigger motor push rod.
(l) Clearance for Fire & Safe mechanism plunger. (F)
(m) Breech block guide grooves. (F)

BREECH BLOCK:- (a) Breech block.
(b) Cartridge face. (F)
(c) Cartridge guides. (F)
(d) Accelerator face. (F)
(e) Transporter stop. (F)
(f) Clearance for T.M. push rod and F & S plunger. (F)
(g) Cam grooves. (F)
(h) Locking recess. (F)
(i) Return spring hosing. (F)
(j) Cocking stud housing. (F)
(k) Guide ribs. (F)
(l) Sear housing. (F)
(m) Sear retainer housing. (F)
(n) Switch plate housing. (F)
(o) Transport housing. (F)
(p) Firing pin housing. (F)
(q) Sear spring retainer keeper housing. (F)
(r) Cocking stud pin. (enlarged head to provide bearing on barrell [sic] extension) (F)

[underlined] FIRING PIN:- - [/underlined] (a) Firing pin spring pin.
(b) Bents. (F)
(c) Firing pin spring.
(d) Firing pin spring housing. (F)
(e) Cocking lever slot. (F)
(f) Striker. (F)

[underlined] SWITCH PLATE:- [/underlined] (a) Plunger.
(b) Spring.

[underlined] COCKING LEVER:- [/underlined] (a) Nose. (F)
(b) Tail pin. (F)

[underlined] SEAR:- [/underlined] (a) Bent. (F)
(b) Spring.
(c) Sear retainer.
(d) Sear spring retainer and head.
(e) Spring housing.
(f) Sear spring retainer keeper and pin.
(g) Stud. (F)
(h) Sear retainer stops. (F)

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TRANSPORTER:-- (a) Arm. (F)
(b) Horn. (F)
(c) Claw. (F)
(d) Plunger.
(e) Plunger spring and pin.
(f) Ejector.
(g) Ejector spring.
(h) Ejector pin.

[underlined] COCKING STUD:- [/underlined]

[underlined] NON-RECOILING PORTIONS: [/underlined]

[underlined] BARREL CASING:- - [/underlined] (a) Muzzle attachment.
(b) Front barrel bearing. (F)
(c) M.A. chamber.
(d) Flash eliminator.

[underlined] BREECH CASING:- - [/underlined] (a) Trunnion block.
(b) Rear barrel bearing. (F)
(c) Lock frame grooves. (F)
(d) Cocking stud slots. (F) (2)
(e) Trigger motor and F & S mechanism.
(f) Plunger clearances. (F) (2)
(g) Joint cover and detent pawl housing. (F)
(h) Detent pawl.
(i) Detent pawl spring.
(j) Breech block guide ribs. (F) (2)

[underlined] LEFT SIDE PLATE:- [/underlined] (a) Transporter cam.
(b) Retainer hole. (F)
(c) Transporter guide.

[underlined] RIGHT SIDE PLATE: [/underlined] (a) Return spring pod recess. (F)

[underlined] BOTTOM PLATE:- [/underlined] (F) (a) Locking piece cam.
(b) Rear sear release unit flanges. (F)
(c) Transporter guide.

[underlined] TOP PLATE:- - [/underlined] (F) (a) Cocking lever bracket.

[underlined] FEED OPENING:- [/underlined] (F) (a) Retaining pawl.
(b) Retaining pawl pin. (2)
(c) Bullet stop.
8 (d) Chute lugs. (4)
(e) Retaining pawl spring.
(f) Cartridge stop.
(g) Filling piece.

[underlined] BACK PLATE:- [/underlined] (a) Catch and pin.
(b) Catch plunger.
(c) Buffer.
(d) Buffer tube screw.
(e) Buffer tube screw plunger spring.
(f) Plunger catch spring.
(g) Buffer discs. (22 in number)
(h) Tube buffer. (F)
(i) Buffer tube screw plunger.

[underlined] BREECH COVER:- [/underlined] (a) Ratchet teeth. (F)
(b) Pin.
(c) Recess. (F)
(d) Slide grooves. (F)
(e) Cover catch.
(f) Cover catch spring.
(g) Catch spring sutd [sic]. (F)
(h) Cover catch axis pin with lever.
(i) Feed lever.
(j) Feed lever stud. (F( [sic]
(k) Feed lever bush.
(l) Feed lever plunger.
(m) Cover transporter guide spring.
(n) Cover transporter spring stud. (F)
(o) Transporter guide ramp. (F)

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[underlined] THE SLIDE:- - - [/underlined] (a) Feed pawl pin.
(b) Feed Pawl extension.
(c) Guide ribs.
(d) Feed Pawl.
(e) Feed pawl spring.

[underlined] LOCK FRAME:- - [/underlined] (a) Projections. (F)
(b) Accelerator stop. (F)
(c) Accelerator.
(d) Accelerator pin.
(e) Accelerator claws. (F)
(f) Accelerator shoulders. (F)
(g) Frame guide ribs. (F)
(h) Barrel return spring.
(i) Rear sear.
(j) Rear sear spring.
(k) Rear sear plunder.
(l) Rear sear pin.
(m) Rear sear cradle.
(n) Rear Sear lever.
(o) Rear sear lever pin.
(p) Rear sear buffer spring.
(q) Barrel return spring plunder.
(r) Barrel return spring plunger guides. (F)
(s) Barrel return spring socket.
(t) Barrel return spring socket pins. (2)
(u) Rear sear buffer spring washer.
(v) Lock frame retainer.
(w) LOck [sic] frame retainer tube.
(x) Lock frame retainer tube stud.
(y) Lock frame retainer spring.

[underlined] RETURN SPRING: [/underlined] (a) Rod.
(b) Stop pin. (F)
(c) Collar.
(d) Head. (F)

[underlined] SEQUENCE OF STRIPPING [/underlined]

2. (a) Remove the flash eliminator.
(b) Remove the back plate
(c) Remove the return spring.
(d) Raise the breech cover, remove the cocking stud and breech block.
(e) Remove the lock frome [sic] and barrel assembly, then separate the lock frame from the barrel extension as follows:- -

[underlined] NOTE:- [/underlined] As the lock frame and barrel assembly are drawn to the rear, the rear sear release unit must be removed. Grip the barrel firmly in the left hand, the lock frame held in the right hand, trip the accelerator with the right thumb.

(f) Separate the barrel from its extension and then the locking piece from the extension.
(g) Remove the barrel locking spring.

[underlined] TO REASSEMBEL [sic]: [/underlined]

(a) Raise the breech cover.
(b) Reassemble the locking piece and the barrel locking spring to the extension.
[underlined] NOTE:- [/underlined] The chamfered edge to be uppermost and to the front.

(c) Reassemble the barrel to the extension and breech up.

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(d) Insert the barrel assembly with the lock frame attached.
[underlined] NOTE:- [/underlined] To assemble the lock frame to the barrel assembly, grip the barrel firmly with the left hand, the lock frame held firmly in the right hand with the forefinger of the right hand raise the claws of the accelerator, enter the projections of the lock frame into the slots of the barrel extension, engage the boss of the extension with the head of the barrel return spring plunger, then push the lock frame right home, i.e., until the accelerator is resting on the stop when the two units will be locked together.

(e) Insert the breech block ensuring that the cocking lever is right forward.
(f) Insert the cocking stud.
(g) Depress the rear sear and push the parts forward.
(h) Replace the return spring.
(i) Replace the back plate and put down the breech cover.
(j) Replace the flash eliminator.

[underlined] NOTE:- [/underlined] When replacing the recoiling portions, great care is to be exercised in order to avoid damage to the muzzle and the barrel bearing. Depress the rear sear in order to clear the rear sear lever from the bottom plate, then fix the rear sear release unit before the group is forced right home. Depress the lock frame retainer plunger and lock the group in positions.

Before assembly of the flash eliminator to the muzzle attachment, the following mixture is to be applied cold to the threats of both muzzle attachment and flash eliminator, by means of a brush. Excessive application is to be avoided.

[underlined] MIXTURE:- [/underlined] Powered Graphite 2 ounces.
Mineral Jelly 6 ounces.
Heat together and allow to cool.

[underlined] STRIPPING THE COMPONENTS [/underlined]

3. [underlined] TO STRIP THE BREECH BLOCK: [/underlined]
(a) Ease the Firing pin spring.
(b) Remove the transporter.
(c) Remove the switch plate, plunger and spring.
(d) Remove the cocking lever pin and lever.
(e) Remove the sear spring retainer keeper.
(f) Remove the sear spring retainer.
(g) Remove the sear spring, sear retainer and sear.
(h) Remove the firing pin.

[underlined] TO REASSEMBLE:- [/underlined]
Reverse the above procedure. Test for functioning by cocking and firing.

4. [underlined] TO STRIP THE LOCK FRAME: [/underlined]
(a) Remove the accelerator.
(b) Remove the barrel return spring and plunger.
(c) Remove the rear sear lever pin and rear sear lever.
(d) Remove the rear sear pin.
(e) Remove the rear sear with plunger and spring.
(f) Remove the barrel return spring socket retaining pins first taking the weight off the buffer spring.
(g) Remove the barrel return spring socket with rear sear buffer spring and washer.
(h) Remove the rear sear cradle.
(i) Remove the retainer plunger spring stud and tube.

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[underlined] LIST OF TOOLS USED FOR STRIPPING [/underlined]

[a] TOOL [b] USE

[a] Braces, carpenters. Bits, stockbolt. [b] Removing and replacing the Buffer Tub Screw.
[a] Spanners, Flash Eliminator. [b] Removing and replacing the Flash Eliminator.
[a] Spanners, .303 inch M.G. Browning Muzzle Attachment [b] Holding the Muzzle Attachment rigid when removing or replacing the Flash Eliminator.
[a] Spanners, Adjustable. [b] Removing and replacing the Locking piece Cam nut.
[a] Tools, Cleaning Muzzle Attachment [b] Cleaning Muzzle Attachment.
[a] Spanner, 1/4 and 5/16 [b] Removing and replacing Loading Gear.
[a] Rods, Cleaning .303 inch M.G. Single Pull-through with Adapter. [b] Cleaning the Bore. Cleaning the Bore of gun on aircraft.
[a] Drift. No. 6, 7, 8. [b] Removing and replacing the Firing Pin Spring retaining Pin.
[a] Drift, No. 9. [b] Removing and replacing the Firing Pin Spring Retaining Pin.
[a] Punch, Copper Face 2 3/4 inches. Hammers, Rubber. [b] Removing and replacing Loading Mechanism
[a] Pliers, Flat Nose. Screwdrivers, Small. [b] Removing and replacing Split Pins, etc.
[a] Tools, Combination, .303 in. M.G. Browning. [b] Removing and replacing the Firing Pin Spring and Ejector.
[a] Cartridge, Drill. [b] Removing and replacing the Return Spring Rod, the Transporter Guide Spring and the Lock from the Retainer.

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[inserted] RUABTECAB [/inserted]

5. [underlined] BACKWARD MOVEMENT: [/underlined]

This consists of the following operations: - -

(a) [underlined] ACTION OF RECOIL:- [/underlined] When a round is fired, recoil action takes place, and gas is momentarily trapped in the muzzle attachment. These combined forces drive the barrel to the rear. The barrel carries with it the barrel extension and the breech block, the latter being locked to the barrel extension, due to the fact that the licking [sic] piece is held upwards by the locking piece cam. The barrel extension boss forces the barrel return spring plunger backwards and compresses the barrel return spring.

(b) [underlined] UNLOCKING OF THE BREECH BLOCK:- [/underlined] As the barrel moves backwards, the locking piece pin strikes the slanting surfaces of the lock frame projections and forces the locking piece down the slope of the locking piece cam. The locking piece is thus withdrawn from the locking recess in the breech block and the breech block is unlocked from the barrel extension.

(c) [underlined] BACKWARD ROTATION OF ACCELERATOR:- [/underlined] During recoil action, the barrel extension bears against the front of the accelerator, and rotates the accelerator backwards as far as the accelerator stop. During this movement the shoulders of the accelerator engage in front of the boss on the barrel extension tang, and hold the barrel extension and barrel to the rear.

(d) [underlined] BACKWARD MOVEMENT OF THE BREECH BLOCK:- [/underlined] As the accelerator rotates backwards its claws bear against the accelerator face of the breech block, and drive the breech block to the rear. During the backward travel of the breech block, the return spring is fully compressed.

(e) [underlined] BACKWARD ACTION OF THE TRANSPORTER:- [/underlined] When the gun is in the fired position, the claw of the transporter is engaged in front of the rim of the cartridge against the cartridge and bullet stops. As the breech block and transporter travel backwards, this round is withdrawn from the belt and carried to the rear, being supported by the ejector. On reaching the chamfered face of the transporter guide, the plunger is depressed. The ramp on the cover then forces the transporter down and carries the live round on to the cartridge face of the breech block.

(f) [underlined] EXTRACTION AND EJECTION:- [/underlined] The empty case in the chamber is held by the cartridge guides on the breech block face. Thus as the breech block travels backwards, the case is withdrawn from the chamber. Being unsupported it is free to fall off the breech block face, when sufficiently clear of the barrel. If the empty case has not already fallen off, positive ejection will take place during the downward movement of the transporter. The rim of the live round bears on the rim of the empty case and forces the empty case off the face of the breech block. In case of the last round in the belt, its empty case, if not already fallen off, will be ejected by the ejector.

(g) [underlined] COCKING ACTION:- [/underlined] The tail of the cocking lever lies in the cocking lever bracket. When the breech block moves backwards, the cocking lever is rotated on its axis and its nose draws the firing pin to the rear and compresses the firing pin spring. The bent of the firing pin bears against the sear and compresses the sear spring. The sear under the influence of its spring, returns, ready to engage the bent when the cocking lever rotates in the forward movement.

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[inserted] [indecipherable words] [/inserted]

(h) [underlined] FIRST ACTION OF THE BELT FEED:- [/underlined] The stud on the feed lever is engaged in a cam groove on top of the breach block. Therefore as the breech block travels backwards, the feed lever is rotated on its axis. The nose of the feed lever, being engaged in a recess of the feed slide, moves the slide across the belt. The feed pawl rides over the round held by the retaining pawl and by the action of the pawl spring engages that round ready for feeding. During the whole of this action, the belt is prevented from leaving the gun by the retaining pawl and spring.

6. [underlined] FORWARD MOVEMENT: [/underlined]

This consists of the following operations:-

(a) [underlined] ACTION OF RETURN SPRING & BUFFER: - [/underlined] On completion of the backward movement, the return spring is fully compressed, and any surplus energy from recoil is absorbed by the buffer discs. Thus the force of recoil is expended, and the return spring is able to drive the breech block forward.

(b) [underlined] SECOND ACTION OF BELT FEED:, - [/underlined] As the breech block moves forward, the stud on the feed lever runs in its cam grooves and rotates the feed lever. This causes the feed slide to feed in the belt so that a live round is brought against the cartridge and bullet stops. During this movement, the retaining pawl and spring are depressed by the next live round, and then, under pressure from its spring, the pawl rises and engages behind that round.

(c) [underlined] RETURN OF THE COCKING LEBER [sic]: - [/underlined] During the forward travel of the breech block, the tail of the cocking lever engages in the cocking lever bracket, and causes rotation of the cocking lever. This rotation resets the lever for cocking, engages the bents of the sear and firing pin, and at the same time gives clearance for the firing pin to travel forward when released.

(d) [underlined] FORWARD ACTION OF THE TRANSPORTER FEEDING OF ROUND:- [/underlined]

As the breech block travels forward, the transporter plunger rides down the sloping face of the transporter plunger rides down the sloping face of the transporter guides until the transporter arm reaches the transporter stop. During the downward movement, the live round is brought into line with the chamber and the firing pin hole. The round is still supported by the ejector. With continued forward movement of the breech block, the live round is fed into the chamber.

(e) When the ejector is brough abreast of the ejector side clearance in the barrel extension, the transporter plunger rides up the transporter cam. This causes the transporter to rise and so lift the ejector clear of the live round, the ejector being forced outwards by the contour of the cartridge case. When clear of the round, the ejector spring returns the ejector to its normal position. As the transporter reaches its fully forward position, its claw rides over the rim of the live round in the belt, and under pressure from the cover transporter guide spring, engages in front of it. At the same time, the ejector, under the influence of its spring, embraces the case of the round, ready to support it, when later it is withdrawn from the belt.

(f) [underlined] FORWARD ROTATION OF THE ACCELERATOR:- [/underlined] When the accelerator face of the breech block strikes the claws of the accelerator, the latter is rotated forward. The accelerator shoulders becomes [sic] disengaged from the barrel extension boss, and the barrel, and the barrel extension are driven forward by the barrel return spring.

[page break]

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(g) [underlined] LOCKING OF THE BREECH BLOCK:- [/underlined] As the barrel moves forward under the influence of the barrel return spring, the locking piece pin is carried away from the lock frame projections. When the breech block is home, and the breech is closed, the locking piece is forced upwards by the slope of the locking piece cam, enters the locking recess of the breech block and locks the breech block to the barrel extension. The breech block being fully locked before the recoiling portions are right forward.

(h) [underlined] FIRING OF THE CARTRIDGE:- [/underlined] When the breech block is right forward, i.e. the breech closed, the lower lug of the sear is brought into line with the rear end of the T.M. push rod slot. The push rod is thus able to strike the sear and drive it inwards. The sear bent disengages from the firing pin bent, the firing pin is carried forward by its spring and strikes the cap of the cartridge.

(i) [underlined] OPERATION OF THE REAR SEAR:- [/underlined] On ceasing to operate the controls, the rear sear lever is released, allowing the rear sear to rise. Thus on the backward movement of the breech block, obtained as the result of the firing of the last cartridge the rear of the breech block depresses the rear sear, which is then forced upwards again by its spring when clear of the accelerator face. On the breech block being forced forward by the return spring, its forward movement is arrested by the accelerator face engaging the bent of the rear sear. The shock of the engagement between breech block and rear sear is absorbed by the buffer spring.

(j) Should the breech block strike the rear sear before it has fully risen, resulting in a partial engagement of the bents, as the rear sear is carried forward in this low position, a projection towards the rear strikes an inclined ramp and forces the bents into full engagement.

[underlined] SAFETY ARRANGEMENTS: [/underlined]

[underlined] UNLOCKING OF THE BREECH AFTER FIRING:- [/underlined] When the recoiling portions are forced to the rear by recoil action, the breech remains closed and locked, because the locking piece continues to rest on the locking piece cam until the bullet has left the muzzle. The projections of the lock frame then unlock the breech by forcing the locking piece down the slope of the cam. On the final forward movement of the Recoiling Portions the Locking Piece is held up in engagement with the Breech Block by its base sliding on the upper step of the Locking Piece Cam. During this period the breech is positively locked. The push rod of the trigger motor on the plunger of the Fire & Safe unit is so positioned that it cannot operate on the Sear to disengage it from the firing pin, until the recoiling portions are home and the breech is locked.

[underlined] MISCELLANEOUS [/underlined]

7. [underlined] BREECHING UP THE BARREL: [/underlined] [deleted] A [/deleted]

Breeching up, i.e., the correct positioning of the breeech [sic] end of the barrel in relation to the front of the breech block, when the locking piece is fully engaged in its loocking [sic] recess, (although easily carried out), required to bee [sic] done with care.

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There must be no cartridge or empty case in the chamber while making this adjustment, and assuming the gun to be completely assembled, the sequence of operations are as follows:- - -

(a) Raise the breech cover and remove back plate and return spring.
(b) Remove the breech block and withdraw the recoiling portions to the rear until the breech (notched) end of the barrel is about 1 1/2 to 2 inches clear of the gun side plates.
(c) Remove the lock frame from the barrel extension.
(d) Raise and move leftwards the barrel locking spring from engagement with the locking notch, and rest the spring on the barrel extension.
(e) Unscrew the barrel about one quarter of a turn.
(f) Remove from the breech block the transporter, switchplate, plunger and spring, cocking lever axis pin, and cocking lever.
(g) With the breech block in this condition, reassemble it to the barrel extension.
(h) By means of the barrel, rotate the assembly through 180 degrees, and see that the locking piece is in full engagement with the breech block.
(i) While keeping the locking piece in full engagement, carefully screw up the barrel until its breech end can be felt to bear against the front surfaces of the breech block.
(j) Engage the barrel locking spring in the appropriate locking notch (should) a notch not register with the spring when the latter is moved back to its central position, unscrew the barrel required distance to allow it to engage with the next notch). In no circumstances is the locking spring to be filed or altered in any way to make it engage with a notch.
(k) Return the assembly in this condition fully home in the [missing letter]un, while steadying the top of the barrel extension with the left hand, test the breech block for any movement in relation to the barrel extension in a fore and aft direction. If there is any fore and aft movement, remove the assembly and screw up the barrel one notch further and retest.

[underlined] Note:- [/underlined] By this means, the gun should be breeched up to the minimum possible clearance, but care must be taken not to “over-breech” the gun. Over-breeching can be detected when the gun is being assembled; if the breech block and barrel extension cannot be pushed fully home by reasonable pressure of the hand on the cocking stud, the gun is “over-breeched”.

8. [underlined] CHANGING FEED DIRECTION: [/underlined]

For right hand feed the undermentioned components are positioned as stated. ositions [sic] are reversed for the left hand feed.

(a) Ejector nose and spring on left od transporter.
(b) Switch plate, the rear of the groove in the switch plate corresponding with the letter “R” on the breech block.
(c) Retaining pawl and spring; on the right of feed opening.
(d) Filling piece; on left of feed opening.
(e) Bullet stop; on left of feed opening.
(f) Cartridge stop; on left of feed opening.
(g) Feed pawl extension; assembled to feed [underlined] pawl on side of nearest rear of gun. [/underlined] (When changed for left hand feed, in the same position relative to the gun).

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(h) Slide filling piece (MK. I* and I** guns only) on side of feed pawl opposite to feed pawl extension. (Same relative position for left hand feed.)
(i) Slide; assembled with feed pawl to right.
(j) Feed lever plunger and spring in lower hole at side of feed lever with cover raised.

9. [underlined] FITTING TRIGGER MOTOR & LOADING MECHANISM: [/underlined]

When fitted, the trigger motor needs no adjustment, being located by the projection on the trigger motor bracket and the locking stud. The locking stud nut must be kept tight. Excessive tightening is liable to strain the trigger motor bracket. The operating handle of the loading mechanism can be adjusted for position.

10. [underlined] BELT FILLING: [/underlined]

(a) Links must be new and undamaged, all oil being removed with petrol, M.T., Grade 111.
(b) Rounds must be correctly positioned by passing through positioning machine. The distance from base of cartridge to top edge of link is to be between 2.072 inches and 2.052 inches.
(c) After filling all brass chippings and filings are to be removed from the belt before stowage in ammunition tank.

11. [underlined] LOADING THE GUN: [/underlined]

(a) Raise the cover and place the first cartridge against the cartridge and bullet stops. Engage the transporter claw. Close the cover.
(b) Operate loading mechanism fully to the rear, then reposition it right forward. The gun is then fully loaded; the breech block being held to the rear sear, a round being held on the breech block face in line with the chamber.

12. [underlined] UNLOADING THE GUN: [/underlined]

(a) Raise the cover. Operate the loading mechanism fully to the rear. Raise the transporter with forefinger, allowing the cartridge supported by the ejector to drop through the ejection opening.
(b) Remove the belt from the feed opening. Replacing the loading mechanism in its forward position. Operate the control to allow the breech block to go forward. Close the cover.

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J – 1

[underlined] APPENDIX “A” [/underlined]

[underlined] STOPPAGES AND IMMEDIATE ACTION [/underlined]

1. [underlined] STOPPAGES: [/underlined]

(a) The chief stoppages are primarily due to such defects as faulty breeching up, misalignment of chutes, fualty [sic] ammunition, short or broken firing pin, weak or broken firing pin spring, failure to feed, broken or faulty transporter, damaged cartridge guides on breech block and excessive friction. Stoppages can be reduced to a minimum by the careful observance of maintenance instructions.

(b) The position of the cocking stud will indicate the action that must be taken to clear a particular stoppage.

The positions are as follows:- -

[underlined] First Position:- [/underlined] At the forward end of its slot.
[underlined] Second Position:- [/underlined] From nearly right forward to halfway back in its slot.
[underlined] Third Position:- [/underlined] More than half-way back in its slot.
[underlined] NOTE:- [/underlined] In reading over the stoppage table it will be noticed that the majority of stoppages are due to faulty maintenance.

2. [underlined] IMMEDIATE ACTION: [/underlined]

(a) Immediate action is the immediate application of a probable remedy for a stoppage based on the position of the cocking stud. It must not be considered to be complete until the gun is again functioning satisfactorily. The immediate action table is set out to give a clear indication of the nature and cause of each stoppage and the probable remedy.

(b) The type and number of stoppages that can be cleared in the air will depend on the installation and the spare parts carried in the aeroplane.

[underlined] NOTES: [/underlined] (i) Excessive fouling in the muzzle attachment, a defective barrel return spring or a displaced barrel locking spring will cause a stoppage in the second position.

(ii) Faulty breeching up of the gun will cause a stoppage due to a separated case or to the recoiling portions not going fully forward.

(iii) A broken transporter guide spring or a bent or damaged return spring rod may cause stoppages in various positions.

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[underlined] IMMEDIATE ACTION TABLE [/underlined]

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[a] POSITION OF COCKING STUD [b] IMMEDIATE ACTION [c] RESULT [d] CAUSE [e] REMEDY

[a] First:- [b] Cock the gun. Fire and watch feed. [c] (1) Gun fires [d] (1) Misfire due to defective ammunition. [e] (1) Nil.
[c] (2) Feed takes place, but gun does not fire. [d] (2) (i) Defective firing pin or spring. (ii) Dirt, congealed oil or brass chips in firing pin way in breech block (iii) Defective firing control mechanism or insufficient pressure in the system. [e] (2) Unload. (i) Change breech block. Reload and continue firing. (ii) Remove and clean breech block or change breech block. Reload and continue firing. (iii) Examine and test firing control mechanism.
[c] (3) Feed does not take place, gun does not fire. [d] (3) (i) Defective transporter (ii) Defective feed pawl spring. (iii) Defective retaining pawl spring. [e] (3) Unload. (i), (ii) & (iii):- Change the defective part. Reload and continue firing.

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J – 1

[continued from previous page]

[a] Second:- [b] Cock the gun. Fire. [c] (1) Gun repeats stoppage. [d] (1) (i) Transporter fails to lift due to a defective plunger or spring (ii) Loose link jammed in feed-way. (iii) Cross feed due to cartridge jamming in feed-way. [underlined] NOTE:- [/underlined] (1) (iii) May also cause a stoppage in the first position. (iv) Separated case. [e] (1) Unload. (i) Change transporter. Reload and continue firing. (ii) Clear link. Ensure that feed pawl leg is not damaged. Reload and continue firing. (iii) Adjust belt. Reload and continue firing. This stoppage can be practically eliminated by correct filling and positioning of cartridges in belt. (iv) If inspection indicates that stoppage is not due to above, use clearing plug to remove the separate case unless it is brought out by the round on the breech face. Reload and continue firing.

[a] Third:- [b] Cock the gun, raise breech cover. Clear the gun. Operate rear release unit. Close the breech cover Cok [sic] the gun. Fire. [c] (1) Gun fired. [d] (1) Defective ammunition. Empty case not extracted from chamber or ejected from breech block. [e] (1) Nil.
[c] (2) Gun repeats stoppage. [d] (2) (i) Defective breech block. (ii) Defective ejector. [e] (2) Unload. (i) Change breech block. (ii) Change transporter. Reload and continue firing.

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[underlined] BREECH BLOCK AND COMPONENTS [/underlined]

[diagram]

[page break]

[diagram]

[page break]

[diagram]

[underlined] LOCK FRAME [/underlined] R J A

[page break]

[underlined] PARTS OF THE BARREL EXTENSION [/underlined]

1. Barrel
2. Locking notches
3. Ejector top clearances
4. Ejector side clearances
5. Barrel locking spring
6. Barrel locking spring housing
7. Breech Block guide grooves
8. Fire and Safe unit plunger clearances
9. Tang
10. Boss
11. Stud
12. Locking Piece cam grooves
13. Locking Piece pin clearances
14. Lock frame extension clearances
15. Locking piece
16. Locking piece pin.

[page break]

[diagram]

[underlined] BARREL EXTENSION [/underlined]

[page break]

[underlined] BREECH COVER PLATE [/underlined]

[diagram]

[underlined] BARREL CASING [/underlined]

[diagram]

[underlined] BODY [/underlined]

[diagram]

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[inserted] Brake off
gas on
Mixture control full [indecipherable word]
Throttle tensin [sic] correct
Switchs [sic] on
suffiant [sic] gas In [indecipherable word] Oil Trim normal
[two indecipherable words] in conjunction with [indecipherable word]
Air Speed
Trim of bank of compass check in the air
Altimeter set at zero
[indecipherable word] tab set at position for take off
communications favourable.
No [indecipherable word] in cockpit
Fire Extinguisher [indecipherable word]
Controls moving freely and in [two indecipherable words]
harness of parachute [indecipherable word] & comfortable
no [indecipherable word] coming in on the rear
all clear in front. [inserted]