This week’s DTIC document is one well worth reading in the interest of understanding the AR-15’s early deployment and subsequent “fall from grace” later in the 1960s. It bears more detailed examination than I usually put into the Weekly DTIC, so this will be a longer post than usual. The document is DARPA’s Field Test Report, AR-15 Armalite Rifle, a controversial document extolling the virtues of the early AR-15 in Vietnam. The basic thesis of the document is best summed up in this quote:

Analysis: Based on the numerical ratings and the comments of US Advisors and VN Unit Commanders, the AR-15 is the most desirable weapon for use in Vietnam for the following reasons: 1. Ease of training. 2. Suitable physical characteristics. 3. It is easy to maintain. 4. It is more rugged and durable than present weapons. 5. It imposes the least logistical burden. 6. It is the best weapon for al-around tactical employment. 7. Its semi-automatic firing accuracy is comparable to that of the M1 Rifle, while its automatic firing accuracy is considered superior to that of the Browning Automatic Rifle. 8. Vietnamese troops, Commanders and US Advisors prefer it to any other weapon presently being used in Vietnam.

The document also contains several statements that have become controversial, or which go against common wisdom of the subject. Discussion of some of these statements will be handled below:

(d) (C) Test 04, Marksmanship ability, unknown distance. (i) (C) The ARVN soldier’s ability to deliver accurate semi-automatic fire on targets of unknown range using the AR-15 and the M2 Carbine is comparable.

This is something I did not expect before reading this document. It’s unclear exactly what ranges the firearms were used, and whether those ranges were unknown to everyone (as in, perhaps the ranges were unknown because they were in combat), or just the shooters (as in a test). I would hazard a guess that the unknown ranges did not extend very far; I’ve found my ability to make hits with an M1 Carbine even at known distances beyond 200m to be very limited. In contrast, I have had no problems firing AR-15s out to 800+ meters.

(i) (C) The trajectory of the AR-15 bullet is not significantly affected when fired through dense underbrush at ranges up to 50 meters. (ii) (C) The AR-15 round will penetrate jungle undergrowth equally as well as the M2 Carbine round at ranges up to 50 meters.

Later in the document, a full brush penetration test is given:

Test No. 8. Brush Penetration.

Purpose: To determine whether dense brush and undergrowth affects the trajectory of the AR- 15 bullet and to compare its ability to penetrate heavy foliage with that of the MZ Carbine.

Method:

a. Silhouette targets were positioned behind dense underbrush which generally consisted of bamboo saplings, bush, grass and vines. From a distance of 15 meters, both the AR-15 Rifle and the M2 Carbine were fired at the targets.

b. The distance was then increased to 50 meters and the targets were fired upon again. (Beyond 50 meters it was impossible to distinguish a target, so this was considered an acceptable maximum distance for the test).

c. Procedures a and b above were repeated several times with foliage of varying density.

Analysis:

a. The trajectory of the AR- 15 bullet is not significantly affected when fired through dense underbrush at ranges up to 50 meters.

b. The AR- 15 round will penetrate jungle undergrowth equally as well as the M2 Carbine round at ranges up to 50 meters.

An unequivocal summary of the opinions of the early users of the AR-15 rifle is also given in the first part of the document

e. (C) The Combat Evaluation (Annex “A”) shows that all US Advisors and Vietnamese Commanders who participated in the evaluation prefer the AR-15 to any other weapon with which the RVNAF are now armed. The lethality of the AR-15 and its reliability record were particularly impressive. All confirmed casualties inflicted by the AR-15. including extremity hits, were fatal (see photographs 7 and 8, Annex “D”). The high degree of reliability and trouble-free performance of the weapon reflected in previous test reports (Ref 1. c., 1. d. , and 1. f. ) was also noteworthy during the testing and evaluation here. No parts breakage was encountered while firing approximately 80,000 rounds during the Comparison Test. Only two parts have been issued to date to replace breakage for the entire 1.000 weapons. Stoppages on the AR-15 are easily cleared by the individual soldier through the application of “immediate action”.

The mentioned high lethality of the AR-15 rifle is still a subject of much contention. However, in this early report, the terminal effects of the rifle are described with considerable reverence by RVNAF commanders and their US advisors in the ARPA report:

(1) (C) “On 160900 June 62, one platoon from the 340 Ranger Company was on an operation vic. YT260750 and contacted 3 armed VC in heavily forested jungle. Two VC had carbines, grenades, mines, and one had a 4 ANNEX “A” CONFIDENTIALCONFIDENTIAL SMG. At a distance of approximately 15 meters, one Ranger fired an AR-15 full automatic hitting one VC with 3 rounds with the first burst. One round in the head-took it completely off. Another in the right arm, took it completely off, too. One round hit him in the right side, causing a hole about five inches in diameter. It cannot be determined which round killed the VC but it can be assumed that any one of the three would have caused death.

…

(2.) (C) “On 9 June a Ranger Platoon from the 40th nf Regt was given the mission of ambushing an estimated VC Company. The details are as follows: a. Number of VC killed: 5 b. Number of AR-15’s employed: 5 c. Range of engagement: 30-100 meters d. Type wounds: 1. Back wound, which caused the thoracic cavity to explode. 2. Stomach wound, which caused the abdominal cavity to explode. 3. Buttock wound, which destroyed all tissue of both buttocks. 4. Chest wound from right to left, destroyed the thoracic cavity. 5. Heel wound, the projectile entered the bottom of the right foot causing the leg to split from the foot to the hip. These deaths were inflicted by the AR-15 and all were instantaneous except the buttock wound. He lived approximately five minutes.

…

Five VC were hit, all five with body wounds, and all five killed. Four were probably killing wounds with any weapon listed, but the fifth was essentially a flesh wound. The AR-15 made it a fatal wound.

…

(9.) (C) “On 13 April, 62, a Special Forces team made a raid on a small village. In the raid, seven VC were killed. Two were killed by AR-15 fire. Range was 50 meters. One man was hit in the head; it looked like it exploded. A second man was hit in the chest,; his back was one big hole. ” (VN Special Forces)

It’s tempting to dismiss reports this dramatic as simply exaggerated hearsay, but I do not. Naturally, these anecdotes do not make a solid and rigorous case for the .223 round having magical killing ability – only laboratory tests could do that – but I do believe they actually happened. I find it difficult to believe that the Rangers and Green Berets quoted were mistaken, and terminal effects such as they describe are possible with hits from the .223 caliber, and have been documented in other cases. When viewing pictures of some very grievous wounds caused by the 5.56mm caliber, “exploded” is definitely a word that comes to mind.

Nor is the idea that the .223 caliber was exceptional in this regard so far-fetched. The Pig Board tests of the 1920s showed the greatest terminal effects at ranges under 300m with the .256 caliber round (which was a little more powerful than the .250 Savage) – the smallest caliber tested:

At 300 yards the caliber .256, 125-grain flat-base bullet gave by far the most severe wounds in all parts of the animal. All calibers caused very severe trauma, but the .256 flat-base bullet seemed to be in a class by itself.

– Hatcher’s Book of The Garand, Julian S. Hatcher

Why a smaller caliber would perform so dramatically better is a good question – but a theory describing this has existed since the 1930s, and was the subject of our very first DTIC post. In short, physics dictates that the smaller a homologous projectile gets, the proportionally shorter the distance until upset in dense media will be; restated: Smaller caliber bullets yaw sooner.

As the subject of another DTIC post proved, however, this effect is no guarantee of terminal performance. The orientation of a bullet as it leaves the muzzle of a firearm is chaotic; the projectile can yaw dramatically in air before settling down due to the gyroscopic forces imparted by the rifling. Collectively, this is called the “fleet yaw problem”.

So not only are the anecdotes in the ARPA report valid, but they do represent some level of exceptional performance by the 5.56mm caliber versus other calibers then in service.

This tempers the current view of 5.56mm effectiveness, broadly speaking. The ammunition used when the ARPA report was being written were pre-M193 specification, but were broadly similar to that round, except for having a somewhat better ballistic coefficient. The terminal effects of Belgian-designed M855 ammunition are comparable to this ammunition, too, meaning there is little reason to expect anything to have changed in this regard.

It makes sense, then, that M855 has not been characterized in official reports as a “poor” terminal performer, but an “inconsistent” one; this is precisely the result we’d expect to see for a round with generally good yaw characteristics but still totally subject to the fleet yaw problem. Still, the conclusion that results like those in the ARPA report are possible – or even likely – does not seem like a misguided one to me.

The ARPA report really does have a lot of interesting information and anecdotes – so much that I’ve found myself having covered less than half of what I wanted, while still sitting on an article of over sixteen hundred words. I highly recommend readers click through and read the report in its entirety.