I know this is a something of a silly and perhaps irrelevant question, but I’m going to ask in anyway, since it’s been puzzling me for over two decades. I was in the army in the mid-80s. I was infantry (11-B), stationed at Fort Ord, California and Fort Sherman, Panama. When I enlisted we still had the old M-16 A1s; we got the A2s about a year before I completed my term of service. I also attended sniper school, where we trained with the so-called “M-21 system,” which (for anyone who doesn’t already know) is an accuraized M-14 fitted with a scope and firing match grade ammo. In sniper training we received the common sense instruction that the best way to fire from the prone position using a sandbag rest is to remove one’s hand from beneath the weapon—since any human appendage is certain to wiggle at least a little—and wedge the M-21’s magazine and receiver tight against the sandbag so as to obtain maximum stability. I did this with great results. In fact, I was one of the best marksmen in my class. Here’s the rub: We were told that the same technique should be used with all weapons—including the M-16—which sounded like good advice at the time. But when I tried shooting the M-16 this way, I wasn’t anywhere near as accurate as I had been using the old “hand between the weapon and sandbag” approach I’d learned in basic training. So why did a seemingly common sense shooting technique produce excellent results with the M-21/M-14 and horrible ones with the M-16? Okay, I know asking something like this means I’m bored and have nothing better to do with my evening, but I’d still like to know. Thoughts?