To compensate for lower magazine capacity, soldiers could carry more magazines, but that would add weight. An unloaded XM7 weighs 8.18 pounds, while the unloaded M4A1 weighs 6.54 pounds.

It proved mechanically reli­able, but so is the M16 when given at least minimum care. The AK-47 has a heavy sheet steel 30-shot magazine compared to the lightweight alloy 18-­shot M16 magazine.

The XM7 has a 20-round capacity compared to the Army’s previous M4A1 30-round magazine. Soldiers’ current basic combat load means they carry seven magazines into battle for M4A1 carbines ...