Initial Inspection And Assembly Inspection Of Rifles Major Groups

The rifle's four major groups are packaged as shown in Figure 2-1.

1. Upper Receiver

2. Bolt Carrier Group

3. Lower Receiver

4. Bipod Assembly

Ensure all components are present (see paragraph 1-7, page 1-4) and inspect for obvious damage, reporting any discrepancies to the Barrett factory. Detailed inspection should be conducted as follows:

Figure 2-1. Four Main Groups

2.1.1.1 INSPECTION - THE UPPER RECEIVER

Major Component Groups M16 Rifle

(1) Barrel springs (1), must not be overstretched, and each coil should be tight, with no spaces between coils.

(2) Impact bumpers (2) should be in good condition (not frayed, cracked, or twisted).

(3) The muzzle brake (3) should be tight and fully screwed on (see 3.3.4, page 28 for installation procedures).

(4) The upper receiver (4) should not be cracked, bent, or burred. Pay special attention to the hinge lip at the front of the receiver to ensure that it is not cracked, bent, or deformed in any way.

(5) The barrel (5) should be clean and free of obstruction.

(6) All scope mountings (6) should be tight, in good condition, and free of oil (iron sights, front (7) and rear (8), may be lightly oiled at pivot points to prevent corrosion).

2.1.1.2 INSPECTION - THE BOLT CARRIER GROUP

Firing Mechanism Bolt Action
Figure 2-3. Bolt Carrier Group

(1) Ejector and extractor (1) must be checked to ensure they are under spring tension, and neither chipped nor worn.

(2) With firing mechanism decocked (use rear lock pin to depress sear (2), depress the bolt latch and manually work the bolt in and out, feeling for any roughness, which may indicate wear, corrosion, or dirt/grit in the carrier (4).

(3) Push the bolt (5) into the carrier and inspect for firing-pin protrusion. Check firing-pin hole (on bolt face) to ensure it is not eroded or elongated. Bolt face should not be pitted.

(4) Inspect bolt latch (3): should not show any deformation.

(5) Swing the cocking lever (6) forward. The sear should capture the firing-pin extension before the cocking lever is fully depressed.

2.1.1.3 INSPECTION - LOWER RECEIVER

Caliber Gun Assembly

(1) With bolt carrier in place, pull it rearward and check to see that the mainspring (1) moves freely (full travel) and is not deformed.

(2) Hold bolt carrier back and down approximately % in (6 mm) under mainspring housing (2) (sheet metal closure). With the thumb safety (3) on fire, pull the trigger. Firing mechanism should function (a slight rise in bolt carrier is normal). If the housing is bent, the bolt carrier will rise excessively as the trigger is pulled, preventing proper functioning.

(3) Lower receiver (4) should not be cracked, bent, or burred.

(4) Check bipod assembly (5) and mounting hardware to see that legs extend and hardware functions properly.

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  • Eleanor
    How works bolt action ejector?
    9 years ago
  • gerda
    How airsoft bolts mechanisms work?
    8 years ago
  • james colley
    How to decock a bolt action rifle?
    8 years ago
  • ROSAMUNDA
    How bolt action mechanism working?
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