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| CHAPTER 1. | INTRODUCTION |
1. PURPOSE AND SCOPE
a. This manual furnishes guidance for commanders in the training and employment of the Davy Crockett section in infantry and armor units. It is applicable to all units receiving a Davy Crockett team (augmentation) under TOE 7-97T.
b. Throughout this manual the term parent unit will apply to the battle group in infantry units and the battalion or squadron in armor units. The term company will also apply to troop.
c. Organization and tactical employment of the Davy Crockett within the new division organizations (ROAD) are covered in the appropriate unit manuals.
d. Material contained herein applies to nuclear warfare only.
e. Users of this manual are encouraged to submit recommended changes or comments to improve the manual. Comments should be keyed to the specific page, paragraph, and line of the text in which change is recommended. Reasons should be provided for each comment to insure understanding and complete evaluation. Comments should be forwarded direct to the Commandant, United States Army Infantry School, Fort Benning, Ga.
2. DESCRIPTION
a. The Davy Crockett weapons system consists of two weapons, the XM28 (light weapon) (fig. 1) and the XM29 (heavy weapon) (fig. 2). Both weapons function in the same manner, use the same fire control equipment, and fire the same major caliber ammunition-the principal differences between the two are the size and weight of the barrel, the range of the weapon, and the manner of adjustment of fire on target. Fire adjustment with the XM28 (light weapon) is made by an attached 20-mm spotting rifle; and with the XM29 (heavy weapon), by using major caliber (279-mm) high explosive ammunition.
b. The light and heavy weapons are open-breech, recoilless, smooth bore, single shot, low-angle fire, muzzle-loaded weapons.
c. The light weapon consists of a 120-mm barrel with a 20-mm spotting rifle attached. It can be mounted on a tripod for ground use or by a special adaption kit on a ¼-ton truck. Two fixed propellants and two launching pistons, designed for use in this weapon only, are used to propel the major caliber projectile to the target. The light weapon has the capability of engaging targets at ranges up to 2,000 meters.
d. The heavy weapon consists of a 155-mm barrel mounted on a tripod for ground use. In the infantry battle group, armor battalion, or armored cavalry squadron it is stowed in the M 1 rn, full-tracked armored personnel carrier. When transported in this manner, it can be fired from the ground mount only. In the airborne battle group, the weapon is mounted by means of an adaption kit on a ¼-ton truck, and can be fired from the ¼-ton carrier or from the ground mount. A launching piston and one of two different type fixed propellants, all designed specifically for this weapon, are used to propel the major caliber projectile to the target. A "Zone I" propellant is used for ranges up to 1,900 meters, and a "Zone 11" propellant is used from 1,700 to 4,000 meters.
FIGURE 1. Light weapon system XM28.
FIGURE 2. Heavy weapon system, XM29.
e. The 20-mm spotting round (XMI01) and the HE major caliber projectile (XM:{90) detonate on impact.
3. TECHNICAL DATA
a. XM28 (Light weapon)
| Num | Sub Num | |
Weight (lbs) | Diameter | Length (Inches) | Height (Inches) |
| (1) | Barrel, recoiless, XM63E1 with bracket | 73.5 | 120-mm | 60 7/16 | ---------- | |
| (2) | Rifle, spotting, XM69 | 7 | 20-mm | 27 1/2 | ---------- | |
| (3) | Mount, tripod, XM120 | 23 | ---------- | 40 3/8 (folded) | 41 assembled | |
| (4) | Mount, vehicle | 84 | ---------- | 25 | 17 1/4 | |
| (5) | Sight unit (telescope XM107 and telescope mount XM117) | 5 | ---------- | ---------- | ---------- | |
| (6) | Overall weight of the light weapon to include barrel, spotting rifle, tripod mount, and sight unit. | 108.5 | ---------- | ---------- | ---------- | |
| (7) | Overall length of light weapon | ---------- | ---------- | 60 7/16 | ---------- | |
| (8) | Pack boards (15 ins. wide) | 7 | ---------- | ---------- | 24 | |
| (9) | Maximum range 2,000 meters | 7 | ---------- | ---------- | 24 | |
| (10) | Launching piston drop pattern - 150 - 600 meters | |||||
| (11) | Performance characteristics on mount XM120 | |||||
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| (a) |
Elevation firing limits 0 - 800 mils:
1. Maximum elevation - 875 mils. 2. Minimum elevation - 0 mils 3. Per turn of elevation - 8 mils (average) |
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| (b) |
Traverse limits from center position: 1. Traverse screw right or left - 40 mils. 2. Cross tube right or left - 160 mils. 3. Per turn of traverse - 3 mils (average) |
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| (12) | Performance characteristics on vehicle mount | |||||
| (a) |
Elevation firing limits - 0-800 mils: 1. Maximum elevation - 875 mils. 2. Minimum elevation - 0 mils. 3. Per turn of elevation - 8 mils (average) |
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| (b) | Traverse right or left - 6,400 mils. |
b. XM29 (Heavy weapon)
| Num | Sub Num | Component | Weight (lbs) | Diameter | Length (Inches) | Height (Inches) |
| (1) | Barrel, recoiless, XM64E2 | 217 | 155-mm | 98 3/8 | ---------- | |
| (2) | Mount, tripod, XM121 | 34 | ---------- | 52 5/8 (folded) | 35 7/8 (assembled) | |
| (3) | Carriage, XM121 (width 12 ins | 60 | ---------- | ---------- | 18 1/2 | |
| (4) | Sight unit | 5 | ---------- | ---------- | ---------- | |
| (5) | Overall weight of the heavy weapons, to include barrel, tripod mount, carriage, and sight unit. | 316 | ---------- | ---------- | ---------- | |
| (6) | Range: | |||||
| (a) | Maximum 4,000 meters | |||||
| (b) | With propellant, XM76, (Zone I), up to 1,900 meters. | |||||
| (c) | With propellant, XM77, (ZONE II), 1,700 - 4,000 meters | |||||
| (7) | Launching piston drop pattern 150 - 700 meters. | |||||
| (8) | Performance characteristics on mount, XM121. | |||||
| (a) | Elevation firing limits 5-800 mils | |||||
| (b) | Maximum elevation - 800 mils | |||||
| (c) | Minimum elevation - 5 mils | |||||
| (d) | Per turn of elevation (average): | |||||
| 1. | Elevation handwheel knob (coarse elevation) - 24 mils | |||||
| 2. | Elevation hand knob (fine elevation) - 8 mils | |||||
| (e) | Traverse: | |||||
| 1. | Right or left - 6,400 mils | |||||
| 2. | Per turn of traversing hand wheel - 15 mils | |||||
c. Ammunition and Accessories
| Num | Sub Num | Component | Diameter | Weight (lbs) | Length (Inches) | Remarks |
| (1) | Cartridges, spotting, XM101 | 20-mm | 1.0 | 7.25 | For XM28 only | |
| (2) | Propellant, XM75 | 120-mm | 11 | 23 | For XM28 only | |
| (3) | Propellant, XM92 | 120-mm | 12 | 23 | For XM28 only | |
| (4) | Propellant, XM76 (Zone 1) | 155-mm | 11 | 26 | For XM29 only | |
| (5) | Propellant XM77, (Zone II) | 155-mm | 19 | 26 | For XM29 only | |
| (6) | Piston, launching, XM1 | 120-mm | 11 | 38,11 | For XM28 only | |
| (7) | Piston, launching, XM5 | 120-mm | 12.3 | 38.11 | For XM28 only | |
| (8) | Piston, launching, XM2 | 155-mm | 32.4 | 73.44 | For XM29 only | |
| (9) | Projectile, atomic, super caliber, 279-mm, XM388 | 279-mm | --------- | 30.97 | For XM28 and XM29 | |
| (10) | Projectile, atomic, super caliber, 279-mm | 279-mm | --------- | 30.97 | For XM28 and XM29 | |
| (11) | Projectile, atomic, super caliber 79-mm, practice XM390 | 279-mm | ---------- | 30.97 | For XM28 and XM29 | |