Principles Of Operation

1.3.1 GENERAL FUNCTIONING. The cycle of operation for the M82A1 Rifle is broken down into eight basic steps (more than one step may occur at the same time). For reference, see Figure 1-4 and the accompanying legend.

(1)

Barrel Key

(12)

Sear

(2)

Impact Bumper

(13)

Barrel Spring

(3)

Bolt

(14)

Mid-Lock Pin

(4)

Bolt Latch

(15)

Cam Pin

(5)

Firing Pin

(16)

Front Magazine Hinge

(6)

Firing Pin Extension

(17)

Magazine Catch

(7)

Bolt Spring

(18)

Disconnector

(8)

Extension Stop Pin

(19)

Trigger

(9)

Accelerator

(20)

Buffer

(10)

Cocking Lever

(21)

Safety

(11)

Sear Spring

(22)

Transfer Bar

Barret Rifle Stripped
Figure 1-4. Identification of Operating Parts

1.3.2 FEEDING. The force of the mainspring pushes the bolt (1), Figure 1-5, forward, toward the barrel extension (2), stripping a cartridge from the magazine and loading it into the chamber. The bolt carrier is moved to the rear by hand when first loading but the bolt carrier handle should be released fully to allow the bolt to come forward freely under spring pressure. The rifle will fire in the semiautomatic mode on subsequent firings.

1.3.2 FEEDING. The force of the mainspring pushes the bolt (1), Figure 1-5, forward, toward the barrel extension (2), stripping a cartridge from the magazine and loading it into the chamber. The bolt carrier is moved to the rear by hand when first loading but the bolt carrier handle should be released fully to allow the bolt to come forward freely under spring pressure. The rifle will fire in the semiautomatic mode on subsequent firings.

Barrett Bolt Carrier Images
Figure 1-5. Feeding Procedure

1.3.3 CHAMBERING. The bolt forces the round fully into the firing chamber (1), Figure 1-6, and the extractor snaps over the case rim. Blockages such as dirt or other debris can prevent full

1.3.3 CHAMBERING. The bolt forces the round fully into the firing chamber (1), Figure 1-6, and the extractor snaps over the case rim. Blockages such as dirt or other debris can prevent full

Chambering Cycle Operation M16

1.3.4 LOCKING. During chambering, the bolt enters the barrel extension (2), Figure 1-6, and the bolt latch (3) engages the bolt latch trip (inside-top of the upper receiver, just behind barrel extension) The bolt latch is depressed, allowing the bolt to retract into the bolt carrier. The bolt rotates due to the cam slot and is locked when its three locking lugs rotate into place in the barrel extension, closing the firing chamber.

1.3.5 FIRING. The trigger (1), Figure 1-7, pivots on the trigger housing pin and presses on the transfer bar (2), causing the bar to rise. The transfer bar engages the sear (3) (housed in the bolt carrier), forcing it upward and out of engagement with the firing pin extension (4). The firing pin extension,

1.3.5 FIRING. The trigger (1), Figure 1-7, pivots on the trigger housing pin and presses on the transfer bar (2), causing the bar to rise. The transfer bar engages the sear (3) (housed in the bolt carrier), forcing it upward and out of engagement with the firing pin extension (4). The firing pin extension,

Boltface Browning

1.3.6 UNLOCKING. When the cartridge is fired, gas pressure exerts a thrust on the bolt face via the case head. The bolt carrier (1), Figure 1-8, carries the bolt (2) and barrel extension (3) to the rear until the accelerator (1), Figure 1-9, protruding beneath the bolt carrier (2), contacts a shoulder in the trigger housing area. The accelerator is then pivoted up, causing the accelerator rod (3) to be pushed out of the bolt carrier. As it protrudes from the front of the bolt carrier, it separates the bolt from the barrel extension. Because of the cam slot in the side of the bolt, the bolt rotates as it travels rearward and unlocks from the barrel extension.

Cocking The Bolt

1.3.7 COCKING. As the bolt carrier recoils to the rear, the cocking lever (4), Figure 1-9, rides the transfer bar (5) back and down, causing it to disconnect from the trigger. The transfer bar is held down in the position by the disconnector and not released until pressure is released from the trigger. After disconnection, the cocking lever swings on its pin and overrides the transfer bar. The other end of the cocking lever protrudes into the bolt carrier and into the firing pin extension. As the cocking lever pivots, it withdraws the firing pin and compresses the firing pin extension spring. The firing pin extension now catches the sear.

Barrett M82a1 Operation

1.3.8 EXTRACTION. As the bolt locking lugs rotate away from the barrel extension, the bolt withdraws from the barrel and the bolt latch (1), Figure 1-10, locks the bolt in its extended position. The extractor (1), Figure 1-11, located on the bolt face (2) and hooked over the rim of the fired case, pulls the case from the firing chamber.

Barrett Cal M82a1
Figure 1-10. Extraction Procedures

1.3.9 EJECTION. As soon as the fired case has been extracted and has cleared the rear of the barrel extension, it is expelled from the rifle by the spring-powered ejector (3).

Barrett Ejection
Figure 1-11. Ejection Procedures

1.3.10 SAFETY MECHANISM. There is a single thumb-lever (1), Figure 1-12, which prohibits the rifle from firing by blocking the trigger from rotating up, effectively preventing it from rotating the transfer bar on to the sear.

Figure 1-12. Thumb Safety Lever

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