P.M.I.

TOPICS:

• CHARACTERISTICS OF THE M4 CARBINE.

• CLEARING THE M-4 CARBINE

• COMPONENTS, AND DISSASEMBLE/ ASSEMBLE OF THE M-4 CARBINE.

• FUNCTIONS CHECK

• CYCLES OF FUNCTIONING

• S.P.O.R.T.S.

• BRM

CHARACTERISTICS OF THE M4 CARBINE

The M4 Carbines are lightweight, gas-operated, air-cooled, magazine-fed. shoulder-fired weapons that can be fired in either three-round bursts, or semiautomatic. The purpose of the weapons is to provide personnel an offensive/defensive capability to engage targets in the field. The adapter rails allows the operator the capability to mount various accessories on to the M4/M4A1 Carbines.

M4 CARBINE

Caliber ................................. 5.56 mm

Weight ................................... w/30 (loaded) round mag 7.5 lb

Length ................................... Buttstock Closed 29.75 in

Buttstock Opened 33.0 in

Mechanical Features:

Riffling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (RH 1/7 twist)

Detachable carrying handle w/integral accessory mounting rail

Buttstock has four positions; closed, 1 R open, 3/4 open, and fully Open.

Firing Characteristics:

Muzzle Velocity . . . . . . . . . . . . . . . . . . . . 2,970 fps

Chamber pressure . . . . . . . . . . . . . . . . . . . 52,000 psi

Cyclic Rate of Fire................. 700-970 rpm (approx.)

Fire Selector ............................ SAFE-SEMI-BURST (M4)

SAFE-SEMI-AUTO (M4A1)

Max Effective Rate of Fire:

Semi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45rpm

Burst/Auto . . . . . . . . . . . . . . . . . . . . . . 90 rpm

CLEARING PROCEADURES ON AN M-4NOTE: If the rifle will not be fired immediately close the ejection port cover.

COMPONENTS, DISSASMBLY/ASSEMBLY OF AN M-4 CARBINE

UPPER RECEIVER AND BARREL ASSEMBLYDO NOT interchange bolts between weapons.• 1. Inspect hand guards (1) for cracks, broken front or rear tabs and loose heat shields.• 2. Inspect front sight post (2) for straightness and check depression of the front detent.• 3. Inspect compensator (3) for looseness.• 4. Inspect barrel (4) for straightness, cracks or burrs.• 5. Inspect charging handle (5) for cracks bends or breaks.• 6. Inspect rear sight assembly (6) for the capability to adjust windage and elevation and the spring should

retain the short range or long range sight in position.• 7. Inspect gas tube (7) for bends or retention to barrel.

BOLT AND BOLT CARRIER ASSEMBLY• 1. Inspect bolt cam pin (1) for cracking or chipping.• 2. Inspect firing pin (2) for bends, cracks or sharp or blunted tip.• 3. Inspect for missing or broken gas rings (3).• 4. inspect bolt cam pin area (4) for cracking or chipping.• 5. Inspect locking lugs (5) for cracking or chipping. Inspect bolt face (6) for• excessive pitting.• 6. Inspect extractor assembly (7) for missing extractor spring assembly with• insert and for chipped or broken edges on the lip which engages the• cartridge rim.• 7. Inspect firing pin retaining pin (8) to determine if bent or badly worn.• 8. Inspect bolt carrier for loose bolt carrier key (9).• 9. Inspect for cracking or chipping in cam pin hole area (10).

LOWER Receiver AND BUTTSTOCK ASSEMBLY• 1. Inspect buffer (1) for cracks or damage.• 2. Inspect buffer spring (2) for kinks.• 3. Inspect buttsock (3) for broken buttplate or cracks.• 4. Inspect for bent or broken selector lever (4).• 5. Inspect rifle grips (5) for cracks or damage.• 6. Inspect for broken or bent trigger (6).• 7. Visually inspect the inside parts of the lower receiver (7) for broken or missing

parts.

FUNTIONS CHECK1. SAFE: Place selector lever on SAFE: Pull charging handle to rear and

release. Pull trigger. Hammer should not fall.

2. SEMI: Place selector lever on SEMI. Pull trigger. Hammer should fell. Hold trigger to the rear end charge the weapon. Release thetrigger with a slow, smooth motion, until the trigger is fully forward (an audible click should be heard). Pull trigger. Hammer should fall.

3. BURST : Place selector lever on BURST. Charge weapon and squeeze trigger, hammer should fall. Hold trigger to the rear, pull charging handle to the rear and release it three times. Release trigger. Squeeze trigger. Hammer should fall.

1. Feeding (Figure 4-3). As the bolt carrier group moves forward , it clears the top of the magazine, the expansion of the magazine spring forces the follower and a new round up into the path of the forward movement of the bolt with enough force to strip a new round from the magazine.

CYCLES OF FUNCTIONING OF THE M-4 RIFLE.

2. Chambering (Figure 4-4). As the bolt carrier group continues to move forward, the face of the bolt thrusts the new round into the chamber.

3. Locking (Figure 4-5). As the bolt carrier group moves forward, The pressure exerted by the contact of the bolt locking lugs and barrel extension causes the bolt cam pin to move along the cam track (located in the bolt carrier) in a counterclockwise direction, rotating the bolt locking lugs in line behind the barrel extension locking lugs. The rifle is ready to fire.

4. Firing (Figure 4-6). With a round in the chamber, the hammer cocked, the firer squeezes the trigger. The hammer strikes the head of the firing pin, driving the firing pin through the bolt into the primer of the round. This ignites and causes the powder in the cartridge to ignite, forcing the projectile from the cartridge and propelling it through the barrel. Before the round leaves the barrel, some gas enters the gas port and moves into the gas tube. The gas is directed into the bolt carrier. The carrier is thus forced to the rear by the expanding gas.

5. Unlocking (Figure 4-7). As the bolt carrier moves to the rear, the bolt assembly rotates until the locking lugs of the bolt are no longer in line behind the locking lugs of the barrel extension.

6. Extracting (Figure 4-8). The bolt carrier group continues to move to the rear. The extractor (which is attached to the bolt) grips the rim of the cartridge case, holds it firmly against the face of the bolt, and extracts the cartridge case from the chamber.

7. Ejecting (Figure 4-9). With the bolt carrier assembly continuing rearward, and the base of a cartridge case firmly against the face of the bolt, the cartridge is then pushed out of the ejection port by the action of the ejector and spring.

8. Cocking (Figure 4-10). The rearward movement of the bolt carrier re-cocks the hammer, and places it back into the firing position.

S.P.O.R.T.S.

1. Slap upward on magazine to makesure it is property seated.

2. Pull charging handle all the way back, and hold.

3. OSERVE the chamber to ensure round has been ejected.

4. Release charging handle to feed new round. Don’t ride the charging handle Forward.

5. TAP forward assist.

6. Shoot

BASIC RIFLE MARKSMANSHIP

TOPICS :

• THE FOUR FUNDAMENTALS OF MARKSMANSHIP: 1. STEADY POSITION 2. AIMING 3. BREATH CONTROL 4. TRIGGER SQUEEZ

• PEER COACHING

• ZEROING

• M-68

THE FOUR FUNDAMENTALS OF MARKSMANSHIP

a. Steady Position. • (1) Nonfiring Handgrip. The rifle hand guard rests on the heel of the hand in the V formed by

the thumb and fingers. The grip of the non-firing hand is light.• (2) Rifle Butt Position. The butt of the rifle is placed in the pocket of the firing shoulder. This

reduces the effect of recoil and helps ensure a steady position.• (3) Firing Handgrip. The firing hand grasps the pistol grip so it fits the V formed by the thumb

and forefinger. The forefinger is placed on the trigger so the lay of the rifle is not disturbed when the trigger is squeezed. A slight rearward pressure is exerted by the remaining three fingers to ensure that the butt of the stock remains in the pocket of the shoulder, minimizing the effect of recoil.

• (4) Firing Elbow Placement. The firing elbow is important in providing balance. Placement should allow shoulders to remain level.

• (5) Non-firing Elbow. The non-firing elbow is positioned firmly under the rifle to allow a comfortable and stable position.

• (6) Cheek-to-Stock Weld. The stock weld should provide a natural line of sight through the center of the rear sight aperture to the front sight post and on to the target. The firer's neck should be relaxed, allowing his cheek to fall naturally onto the stock. A small change in eye relief normally occurs each time that the firer assumes a different firing position. The soldier should begin by trying to touch the charging handle with his nose when assuming a firing position. This will aid the soldier in maintaining the same cheek-to-stock weld hold each time the weapon is aimed.

b. Aiming. (Figure 4-16). Any alignment error between the front and rear sights repeats itself for every 1/2 meter the bullet travels. For example, at the 25-meter line, any error in rifle alignment is multiplied 50 times. If the bullet is misaligned by 1/10 inch, it causes a target at 300 meters to be missed by 5 feet.

(1) Focus of the Eye. A proper firing position places the eye directly in line with the center of the rear sight aperture. When the eye is focused on the front sight post, the natural ability of the eye to center objects in a circle and to seek the point of greatest light (center of the aperture) aid in providing correct sight alignment.

(2) Sight Picture. Once the soldier can correctly align his sights, he can obtain a sight picture. A correct sight picture has the target, front sight post, and rear sight aligned. The sight picture includes two basic elements: sight alignment and placement of the aiming point.

Another good technique to obtain a good sight picture is the side aiming technique (Figure 4-18). It involves positioning the front sight post to the side of the target in line with the vertical center of mass, keeping the sights aligned. The front sight post is moved horizontally until the target is directly centered on the front sight post.

c. Breath Control. (1) The first technique is used during zeroing (and when time is available to fire a shot) (

Figure 4-19). There is a moment of natural respiratory pause while breathing when most of the air has been exhaled from the lungs and before inhaling. Breathing should stop after most of the air has been exhaled during the normal breathing cycle. The shot must be fired before the soldier feels any discomfort.

(2) The second breath control technique is employed during rapid fire (short-exposure targets) (Figure 4-20). Using this technique, the soldier stops his breath when he is about to squeeze the trigger.

d. Trigger Squeeze.

Trigger squeeze is important for two reasons: First, any sudden movement of the finger on the trigger can disturb the lay of the rifle and cause the shot to miss the target. Second, the precise instant of firing should be a surprise to the soldier. The soldier's natural reflex to compensate for the noise and slight punch in the shoulder can cause him to miss the target if he knows the exact instant the rifle will fire.

The trigger finger (index finger on the firing hand) is placed on the trigger between the first joint and the tip of the finger (not the extreme end) and adjusted depending on hand size, grip, and so on.

PEER COACHING

Peer coaching is using two soldiers of equal firing proficiency and experience to assist (coach) each other during marksmanship training.

(1) The coach checks to see that the-• Rifle is cleared and defective parts have been replaced. • Ammunition is clean, and the magazine is properly placed in the pouch. • Sights are blackened and set correctly for long or short range.

(2) The coach observes the firer to see if he-• Uses the correct position and properly applies the steady-position elements. • Properly loads the rifle. • Obtains the correct sight alignment (with the aid of an M16 sighting device). • Holds his breath correctly (by watching his back at times). • Applies proper trigger squeeze; determines whether he flinches or jerks by watching

his head, shoulders, trigger finger, and firing hand and arm. • Is tense and nervous. If the firer is nervous, the coach has the firer breath deeply

several times to relax.

ZERROING THE M-4 CARBINE USING DOWNRANGE FEEDBACK

GROUPING PROCEDURES:

(1) Match-Grade Performance. Shot group at 25 meters.

(2) 2-Centimeter Shot Groups. When firing a standard service rifle and standard ammunition combination the dispersion pattern may be up to 2 centimeters apart without human error.

Shot groups indicate no firer error.

(3) 3-Centimeter Shot Groups. This is the minimum acceptable firing performance. The soldier should ensure he is properly applying the four marksmanship fundamentals.

Shot groups indicate minor shooting error.

(4) 4- to 5-Centimeter Shot Groups. The placement of shots in these groups (about 4 to 5 centimeters apart on the target) reflects considerable shooting error. Any of these three shot groups could have been a change in position, sight picture, breathing, trigger squeeze or an erratic round.

Shot groups indicate considerable shooting error.

(5) 6-Centimeter or Larger Shot Groups. The placement of shots in these groups (more than 6 centimeters apart on the target) reflects major shooting error. Any of these three shot groups could have been a change in position, sight picture, breathing; or trigger squeeze, or the firer may be anticipating the shot. Firers with these shot groups should receive extensive dry-fire training to help correct firing problems.

Shot groups indicate major shooting error.

Shot groups with inconsistent aiming.

SHOT GROUPINGS

Shot groups with consistent aiming and major shooting error.

Shot groups with inconsistent aiming and major shooting error.

Other Potential Problem Areas. Ensure-• Nonfiring eye is not shuttering. • Equipment is fitted properly. • Soldier is not flinching when the trigger is pulled. • Soldier is firing with the dominant eye. • Soldier is wearing glasses if applicable. • Soldier is maximizing full use of the supported position.

• Correct aiming (A), initial shot-group results (B).

Perfect Zero

M68, CLOSE-COMBAT OPTIC

The M68, CCO is a reflex (nontelescopic) sight. It uses a red aiming reference (collimated dot) and is designed for the "two eyes open" method of sighting. The dot follows the horizontal and vertical movement of the gunner's eye while remaining fixed on the target. No centering or focusing is required.

Modified Fundamentals. The fundamentals of marksmanship are modified as follows: 1. The soldier must zero with the same cheek position he will fire with because the parallax free is only effective beyond 50 meters.

2. The preferred method of aiming using the M68 is to keep both eyes open, which allows a much greater field of view and makes scanning for targets much easier. Position the head so that one eye can focus on the red dot and the other eye can scan downrange. Place the red dot on the center of mass of the target and engage.

3. The soldier must keep the rifle and M68 in a vertical alignment each time he fires.

NOTE: The aiming method used to zero must also be used to engage targets. When using the M68, the weapon must not be canted during aiming or firing.

M68 Dry (Nonfiring) Zeroing. • Starting with a securely installed and live-fire zeroed BIS, adjust windage and

elevation on the reflex sight until the center of the aiming dot is at the tip of the front sight post when viewed through the BIS while assuming a normal firing position.

25-Meter Zero Procedures.

When zeroing the M68, CCO at 25 meters, a designated impact zone must be identified on the 25-meter zero target. Starting from center mass of the 300-meter silhouette on the 25-meter zero target, count down 2 1/2 squares and make a mark. This is now the point of impact. From this point, make 4x4 squared box around the point of impact. This box is now the offset and is the designated point of impact for the M68. Soldiers will aim center mass of the 300-meter silhouette and will make adjustments to the M68 so that the rounds impact in the 4x4 squared box, 2 1/2 squares down from the point of aim. Other procedures are the same as standard iron sight procedures.

• Two clicks = 1 centimeter at 25 meters for windage and elevation. • One click clockwise on elevation moves bullet strike down. • One click clockwise on windage moves bullet strike left.