Notes on breaching up of Browning



Notes on breaching up of Browning


Detailed notes concerning stripping and servicing Browning gun. Including stripping down and care of barrels. Additional notes for Browning Mk 2.





Eight page handwritten document


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Breeching up of a Browning.
1/ Assume gun is stripped for cleaning.
2/ Screw barrel to Barrel extention [sic] two complete turns.
3/ Remove from Breech block (1) Transporter. (2) Switch plate and plungers (3) Cocking leever [sic] and axis pin.
4/ Place the Breech block to barrel extension and turn assembly 180°
5/ Hold Locking piece into locking recess under Breech Block
6/ Screw up barrel untill [sic] slight check is felt
7/ Engage the Barrel extension locking spring in barrel locking notches. [underlined] Note [/underlined] if locking spring does not engage in a notch unscrew barrel till it does
8/ Turn assembley [sic] another 180° and the locking piece should fall out of engagement with the Breech Block.
9 Put assembley into barrel casing
10 Hold assembley in foreward [sic] position by the boss and check as follows.

Over Breeching
If the locking notches can be seen in the feed opening the gun is over Breeched

remove assembly and uscrew [sic] barrel one notch and retest.

Under Breeching
If by chance there is fore and aft play in the Breech Block the gun is under Breeched

Remove assembley and screw up one notch and retest.

If by taking the fore and aft play out of the Breech Block, Remove assembley again unscrew one notch and retest. (This applys [sic] [deleted] when [/deleted] only when

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after under Breeching you see the notches on the barrel which denotes [deleted] of [/deleted] over Breeching)

[underlined] Changing feed direction on a Browning [/underlined]
from left to right
1/ Ejector, Nose and spring (on left of Extractor)
2/ Switch plate, the rear of the groove in the switch plate corresponding with the letter R. on the Breech Block.
3/ Feed opening. Belt retaining pawl and spring on right of feed opening. Filling piece on left of feed opening. Bullet stop and Cartridge stop on left of feed opening.
4/ feed slide. Feed pawl lay on top of feed slide.
(pointing inwards always)
5/ Feed Lever. Feed lever plunger and spring with spring replaced into the bottom hole.

The Breech Block sear:- This may be left or right according to direction of fire. Cocking stud and loading Mechanism. This will be fitted on the opposite side to the fire and safe.

Mechanism of Browning Gun.
1 Owing to the very high rate of fire of this gun all the mechaniall [sic] operations are practically insantonius, [sic] the interval between explosions being approx. 1/20th of a second.
2 Recoil:- at the moment of the exptosion [sic] the barrel Extension and Breech Block recoil as a single unit for about 5/16th of an inch. Insuring that the bullet has left the muzzel [sic] before the Breech Block is unlocked the locking piece now rides down its cam, the Breech Block is freed from the Barrel

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extension engages the plunger and compresses the Barrel return spring. The movement tottaling [sic] about 5/8 of an inch and is arrested when the Barrel extension Butts [sic] against the lock frame. at the same time the Barrel Extension pushes the accelorator [sic] upwards outwards and over untill [sic] the two ramps are interlocked with the T shaped projection This locks the B.E. to the lock frame against the pressure of the return spring as the accelorator rotates, its horns strike the rear sear bent on the Breech Block accelerating its backwards movement. The Breech Block in moving to the rear compresses the return spring causing the locking lever through its engagements with the bracket under the top plate to swing foreward [sic] and draw back the fireing [sic] pin. The Breech Block Sear engages the bent of the fireing pin and holds it in the cocked position at the same time a live round which is held by the transporter is with drawn [sic] from the belt to the rear. The Breech Block as it moves away from the Barrel extracts the empty case from the chamber.
On reaching the end of the rear cam, the transporter is forced down by the ramp on the Breech Cover this action brings the live round into position in the cartridge guides the ejector bearing on the emty [sic] case ejects it through the bottom of the breech casing.

The Return.
The Recoil of the Breech Block is arrested when it strikes the Buffer in the Back plate. Provided the rear sear release unit is being operated the Breech Block flies foreward assisted by the return spring during the foreward

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movement of the Breech Block the live round is fed into the chamber and the Transporter plunger meeting the front cam raises the transporter and the ejector is lifted clear of the ramp.
When the bent on the Breech Block stricks [sic] the horns of the accelorator it rotates forward and downwards allowing the Return spring to reassert and return the Barrel Extension and Barrel to the Breech Block.
Altogether in the fireing posusion [sic] the Barrel Extension moves forward. The locking piece rides up the incline surface of the locking piece cam; engages the recess in the Breech Block and locks it to the Barrel Extension. Whilst the last movement is taking place the transporter engages the next round in the Belt under the action of the spring in the feed lever, the Ejector embraces the round ready to support it.

Feed Mechanism.
As the Breech Block travels backwards and forwards the feed lever is caused to ossilate [sic] by the sliding of its stud in the cam grooves on top of the Breech Block. During the backward movement of the Breech Block the feed lever moves the feed slide across the belt with the feed pawl under the round which is held in the feed opening by the Retaining pawl. When the Breech Block travels forward the feed lever swings in the opposite direction and causes the feed slide to move back and Feed in the Belt through the engagments [sic] of the feed pawl of the round. Double Feed is prevented by the feed pawl leg and the

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and the round is brought into position against the Bullet and Cartridge stops ready to be gripped by the transporter at the same time a second is brought over and is engaged by the belt rataining [sic] pawl as each round is withdrawn by the extractor and the link falls away and is ejected from the opposite side of the feed opening from the belt.

Safety Arrangements.
1/ The cam in the Breech Casing is arranged to raise the locking piece and lock the Breech Block to the Barrel Extension before the Barrel and Barrel Extension reach there fully forward position.
2/ The Breech Block sear cannot be engaged by the plunger of the fire and safe unit until the barrel and Barrel Extension are right home. Therefore the firing pin cannot be relesed [sic] prematurely [sic].
3/. If the sear of the Breech Block is accidently Relesed during the forward travel the cocking lever will take weight off the firing pin’s spring and render the force of the blow so that it is insurfishant [sic] to fire.

To Remove feed mechanism.
1/ Remove front split pin of retaining pin
2/ With draw pin to rear
3/ Remove chute lug

To Remove Feed Mechanism.
(opposite side to the feed)
Remove split pin and repeat No. 1 and 2
6/ Remove Bullet stop and chute lug

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7/ Remove filling piece and cartridge stop
8/ Remove Chute lug

To Remove Feed lever.
1/ Remove split pin in Bush
2/ Take out Bush
3/ Remove Feed lever with plunger and spring.

Take care not to let spring fly out
4/ Remove Feed slide.

[underlined] Care of Barrels [/underlined]

the inside of a new Barrel is highly polished this polish deteriats [sic] according to Number of Rounds fired, and methods to preserve as far as possible its initial polish. Barrel maintenance is best considered by minimizing the effects of the following.
1/ [underlined] Powder fouling [/underlined], Caused by the combustion of the cap charge propellant. It is deposited on the bore as a dark film, and if left becoms [sic] very hard.
This type of Fouling is removed as follows.
Use a cleaning rod, and 4”x2” flannalette [sic] soaked in oil, in the Bore. Then remove oily 4”x2” and substitute dry 4”x2” and continue cleaning until barrel has assumed its initial polish.
2/ [underlined] Metallic Fouling [/underlined]:- Caused by metal being stripped off the bullet and deposited along the surface of the bore. Remove as follows. Use wire gauge or Kings Norton Nickle Solvent or (KNS) The former to be used with a double pull through, for “KNS” take 40 [underlined] ccs [/underlined] of specific gravaty [sic] (aprox) [sic] 850 liquid ammonia, and dissolve two tablets of KNS in it. Plug one end of

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Barrel, pour in solution and leave for 30 minutes. If mettalic [sic] fouling is present the solution becomes a dark greenish blue. Repeat operation until solution comes out colourless, after using “KNS” boil out Barrel.
3/ [underlined] Chemical Corrosion [/underlined]. caused by forcing of the products of combustion into the pores of the metal. Detected by a dark colouration of the bore. Remove as follows, Wash out Barrel with boiling water, after using boiling water make sure the barrel is thoughly [sic] dry.
4/ [underlined] Wears [/underlined] Caused by the friction of the bullet or Exessive [sic] use of abrasive materials when cleaning
Detected by use of Barrel gauges.
Tools supplied for use of .303 barrels
1/ Pull through. “Single and Double”.
2/ Cleaning rods
3/ Bore Rods “for Removing broken pull throughs and use with Barrel testing gauges.
4/ Plug and Bore bit and Bore bush
5/ Tools cleaning stick for cleaning lead.
6/ Barrel gauges .303 .307 .308 .310 and 2 lead plug.

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Browning [underlined] Mk II [/underlined]

Length 3’ 8 1/2” Length of Barrel 2’ weight 21lbs 14ozs
Rifling left hand 1 turn in 10” 5 grooves
Rate of fire 1400RPM (approx) used as a fixed or movable gun control of fire rear sear relese unit By manual, pneumatic hydrolic [sic] or electric control. Cooled by air flow over Barrel
Flash eliminator and muzzle attachment

Stripping Sequence
1/ cock and fire
2/ Remove flash eliminator
3/ Raise Breech Cover
4/ Remove Back plate
5/ Remove Return spring and guide rod
6/ Remove Cocking stud
7/ Remove Breech Block
8/ Remove Lock frame Barrel ext. Barrel
9/ Dissengage [sic] Lock frame

Stripping of Breech Block.
1/ Cock and fire
2/ Remove Transporter
3/ switchplate and plunger
4/ Cocking Lever axis pin
5/Cocking lever
6/ Sear Retainer Keeper pin
7/ Sear spring Retainer
8/ Sear spring
9/ Sear retainer
10/ Sear
11/ fireing [sic] pin



“Notes on breaching up of Browning,” IBCC Digital Archive, accessed June 15, 2024,

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