July 31, 2007: Two years ago, field testing of the XM-312, the replacement for the eighty year old, .50 caliber (12.7mm) M-2 ("Ma Deuce") machine-gun, began, in the United States and overseas. Then, nothing. That's because the test results were not encouraging, the biggest shortcoming being the low rate of fire (about 260 rounds per minute). This is about half the rate of the M2, and was believed adequate for the 25mm smart shells the XM312 was originally designed for (as the XM307). But for 12.7mm bullets, it didn't impress the troops. There were some reliability problems, which could be...