American Eagle Bulk Packs sold at Walmart:
1. 150rd Bulk Pack of XM855 (green tip) 62gr for $69, Recommended for carbines.
2. 120rd Bulk Pack of XM193 (plain tip) 55gr for $60.
M855 and M193 Ammunition (FM 3-22.9):
1. The M855 bullet is longer and wider than the M193 bullet and has a different configuration. These differences require different twists in the barrels, lands, and grooves to stabilize the bullet in flight. These differences include the following:
• The M16A1 has a 1:12 barrel twist (the bullet rotates once for every 12 inches of travel down the barrel).
• The M16A2/A3/A4 and the M4 have a 1:7 barrel twist (the bullet rotates once for every 7 inches of travel down the barrel).
2. The M16A1 does not put enough spin on the heavier M855 bullet to stabilize it in flight, causing erratic performance and inaccuracy. The shot groups are--
• 30.48 to 35.56 centimeters (12 to 14 inches) at 91.4 meters (100 yards).
• 182.88 centimeters (72 inches) at 274.2 meters (300 yards).
Note: Although firing the M855 cartridge in the M16A1 rifle is safe, it should only be used in a combat emergency, and then only for close ranges of 91.4 meters (100 yards) or less.3. The M16A2/A3/A4 rifle and M4/M4A1 carbine fire both M193 and M855 ball ammunition with little difference in accuracy to a range of 500 meters. The M16A2/A3/A4 and M4/M4A1 and their ammunition are more effective than the M16A1 at ranges out to and beyond 500 meters due to better stabilization of the round.