On Combat Shooting (Part II)

Anthony G. Williams, in his article Assault Rifles And Their Ammunition: History and Prospects cites this line from Dual Path Strategy Series: Part III - Soldier Battlefield Effectiveness written by the PEO Soldier G5, Strategic Communications Office in August of 2011, to support his idea for a 6.5mm general purpose cartridge (GPC):

"Ultimately, Army service rifles must be general purpose in nature and embody a series of tradeoffs that balance optimum performance for a wide range of possible missions in a range of operating environments. With global missions taking Soldiers from islands to mountains and jungles to deserts, the Army can’t buy 1.1 million new service rifles every time it’s called upon to operate in a different environment."

However, earlier in that paper is contained this section on the range of the rifleman:

The maximum effective range of a weapon system is also a key element as it represents the potential for how far out a Soldier can effectively engage the enemy. This is also critical as it affects a Soldier’s ability to leverage an overmatch advantage. Doctrinally, this means that a Soldier will look to engage the enemy at a range that is greater than the range at which they can be engaged by enemy fire (typically 20 percent). According to FM 3-22.9, Rifle Marksmanship M16/M4 Series, there are three ranges of concern. First, there is the detection range, which must be well beyond the effective range of the weapon system. This provides the Soldier time to prepare to engage the enemy at the farthest possible ranges. The next band is the range overmatch distance, whereby friendly Soldiers can engage the enemy, but the enemy cannot engage the Soldiers. The final band is the threat engagement range where enemy personnel can target friendly forces.

Optimally, friendly forces will engage as the enemy enters the range overmatch area. This advantage is short lived however, since a quickly approaching enemy can move through this area in seconds. For example, according to The Encyclopedia of Land Warfare in the 20th Century, the effective range for AK-47 fired on semi automatic is 400 meters. The effective range for an M4 Carbine is 500 meters. The 100 meter difference provides a decisive range overmatch capability so long as Soldiers are proficient at hitting targets at the 400-500 meter range, which is why extensive marksmanship training is so critical.

The range of a weapon system relies heavily on the ammunition the weapon fires and the length of the barrel. Systems that utilize 5.56mm ammunition typically cite ranges of 500 – 550 meters for point targets while U.S. weapon systems that fire 7.62x51mm typically cite ranges closer to 800 meters for point targets. The rounds actually travel further but tend to destabilize after they slow to subsonic speeds and therefore lose accuracy. Longer barrels allow more of the propellant's energy to be transferred to the projectile, resulting in greater range. The spiral grooves inside a rifled barrel impart spin to the round. The spin stabilizes the round which provides accuracy, though it doesn’t necessarily increase the average range of the system.

Regardless of the range potential for certain weapon platforms, the human factor must be considered. Studies have shown that Soldiers can only consistently hit a human-size target more than 300 meters away 50 percent of the time or less on a qualification range. The numbers are significantly lower when a Soldier is operating in high stress environments. 

Therefore, whether a Soldier is firing a 5.56mm system with an effective range of 500 meters, or a 7.62mm platform with an effective range of 800 meters, what really matters is whether he or she has the skill to hit the target to begin with. Taking the human factor into account, one could argue that the “real world” effective range of a 5.56 system is similar to a 7.62mm weapon platform because the range potential of both platforms significantly exceeds the average Soldier’s marksmanship ability. This is not to say that exceptional Soldiers such as U.S. Army Snipers and Squad Designated Marksmen with specialized training are not fully capable of firing small arms to their maximum potential.

The value of having a system capable of increased range not only depends upon the skill of the operator, but it also depends upon the operating environment. In urban or restrictive terrain, for example, most line-of-sight ranges are significantly less than a weapon’s range potential. In more open terrain, the engagement range increase. For example, according to Lt. Col. Henthorn, in operating environments like Iraq, 80 percent of engagements are less than 200 meters. While in more distributed environments like Afghanistan, only 50 percent of engagements are less than 300 meters. 

What this is essentially saying is that the well-trained rifleman is effective out to 500 meters regardless of the caliber of rifle he is using, even though, in Afghanistan, approximately half of engagements occur beyond 300 meters. Given this, how would issuing GPC-caliber infantry rifles help the rifleman to be more effective?

The paper goes on to talk more about the general purpose round as they define it. Contrary to what Wr. Williams's citation implies, the author of the paper considers the M855A1 EPR to be a true general purpose cartridge, as it can engage a wide variety of targets reliably within the effective range of the rifle. This indicates that what Mr. Williams and the author of the paper (and, indeed, the US Army) mean by "general purpose" ammunition is different.

Regardless, I recommend that the reader follow the link and read the whole thing.