When firing the weapon at high rates of sustained fire the barrel and metal components of the RAS can become hot enough to inflict serious burns. Cover exposed metal portions of the rail with the plastic rail covers. Use the vertical pistol grip during heavy sustained fire.
NOTES: 1. Keep the bottom, left, and right unused rail sections covered with full-length 11 -rib rail cover/heat shield sections. If any accessories are mounted on a rail, cover the remaining rail surface with an appropriately sized rail cover/heat shield. The top full length rail cover/heat shield will be permanently removed if a backup iron sight is installed and replaced with a shorter rail cover/heat shield to protect the firer's nonfiling hand when the barrel is hot.
2. For ease of reference the shorter lengths can be referred to by the number of ribs along their outer surfaces.
b. The even numbered recoil grooves of each rail of the RAS are sequentially numbered within the recoil grooves themselves (Figure 2-16). Each number is preceded by a letter prefix indicating a specific slot on the RAS. The numbers of the top rail have a "T" prefix while those of the bottom rail have a "B" prefix. Additionally, the numbers of the rail to the shooter's left have an "L" prefix while those on the rail to the shooter's right have an "R" prefix. These addresses assist the user in remounting an accessory in the same position, allows standardization on precisely where to mount certain accessories, and identifies reference points for discussions on accessory mounting locations.
NOTE: Each RAS also contains holes within the notches that are threaded l/4-inch deep with 20 threads per inch (Figure 2-16). This is the standard thread size for a camera tripod adapter, which is used to attach standard camera or video accessories. For example, an RAS-equipped M4 carbine with a night vision device mounted may be attached to a standard camera tripod for "hands free" support during long periods of surveillance.
c. Each RAS comes with a vertical pistol grip (Figure 2-17). When installing the pistol grip (3) the rail cover/heat shield must be removed first. Once removed, unscrew the pistol grip lock (1) until the tip (2) is no longer visible through the hole in the pistol grip. Slide the pistol grip onto the RAS (it will cover five notches on the RAS). The tip on the top of the pistol grip lock (1) must then be aligned with a notch and hand tightened. (For further information on these accessories refer to TM 9-1005-319-10.)
Figure 2-17. Vertical pistol grip.
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