THE 7.62X51mm NATO; TURNING COVER INTO CONCEALMENT SINCE 1953

We’ve already discussed other attributes of the 7.62x51mm ball round before, such as long-range performance and terminal stopping power. Today we’ll focus entirely on penetration of the humble ball round.

  

The standard military 7.62 NATO ball round here in the ‘States is the M80, which launches a 147-grain projectile consisting of a soft lead core wrapped in a gliding copper jacket at a muzzle velocity of 2,750 feet per second. Although still standard military issue, this is the Old School Original Recipe T65-type .308 load of 1953 vintage. Some of our NATO allies improved upon the recipe a bit. Belgium’s FN Herstal began feeding the FAL rifle and the MAG58 machine gun with their SS77 ball round and later many of the countries which adopted the CETME/HK G3 and the MG3 machine gun used the 146-grain “NATO Reference” ball load.

The SS77 fires a 144-grain FMJBT bullet at 2,750 fps. The significance of the “BT” is that the bullet is Boat-Tailed, which gives it a better aerodynamic shape and ballistic coefficient. This translates into increased accuracy, especially at longer ranges, and the more streamlined SS77 keeps much of its stabilization during the velocity transition from supersonic to subsonic, somewhere out there around 900 meters, depending on how far above Sea Level you are.

Interesting to know, if you’re a gun nut, but we are getting out there to real sniper ranges and beyond the realm of the humble battle rifle and designated marksmen types. For me and my FALs, 600 meters is our effective range.

Any decent NATO ball round will do the job here. Some of the really good foreign-made surplus ammunition includes the German DAG (145-grain/2,785fps), Portuguese (143-grain/2,740 fps) and South African (143-grain/2785 fps) ball. Also noted their very high quality and consistency are the Lithuanian (146-grain FMJBT) and Malaysian (147-grain FMJ) manufactured surplus ball and at one time Australian equivalent of the M80 was readily available.

At any rate, the M80 ball round can, according to the military, penetrate a quarter inch of sheet steel at 300 yards, pierce an old steel pot helmet at 400 yards and, at 620 meters, penetrate a 3.45mm standard NATO steel plate.

There are a wide variety of factors affecting bullet penetration but the most crucial is the angle of impact. A projectile striking at a flat angle of 90-degrees has the best penetration. As the angle becomes sharper, the penetration becomes less and the probability of a ricochet greater, hence the use of sloped armor on tanks since WWII.

As a quirk of ballistics, modern high-velocity small arms rounds actually deliver much less penetration at closer ranges than at longer ranges. In fact, the 5.56x45mm round performs best at 200 meters and the 7.62x51mm ball achieves maximum penetration at 600 meters! The 5.56x45mm round striking cover at close range is particularly affected due to the small but very fast projectile destabilizing almost instantaneously; the poorest penetration actually occurs inside of 25 meters range. Even with the SS109/M855 62-grain “green tip” projectile, combat in Iraq showed that, “5.56 mm bullets were regularly defeated by the sandwich effect of sheet metal and plastic door linings.” Automobiles being such a common media in urban terrain, this is a decided disadvantage.

The 7.62 NATO and to some extent even the 7.62x39mm AK round offer better penetration of common urban media, to include cars. The old 1993 FM 90-10 offered the following data concerning the penetration of a single round of 5.56mm and 7.62mm ball at 200 meters.

The data shows penetration values nearly double those of the 5.56mm for the 7.62mm but doesn’t really tell us all that much. It confirms that dirt/sand is, as Bert Gummer says, “The best bullet-stopper there is.” and that a single layer of sandbags will stop an individual shot from even a 7.62x51mm round. The 7.62 will penetrate up to 50 inches, or just over four feet, of stacked pine boards, but this information would only seem particularly relevant if you were having a firefight in a lumber yard.

          The new MOUT manual lists the penetration of a single round of 7.62x51mm ball round through various media at different, more common, urban ranges. Note that the greatest penetration of sandbag-type material is achieved at the longest range and that the new manual lists only 41 inches of penetration in pine boards as opposed to the old manual’s 50 inches.

In terms of cover, the manual specifically lists the following as being able to stop a 5.56mm round fired at less than 50 meters.

1.     One thickness of well-packed sandbags.

2.     A 2-inch concrete wall (non-reinforced).

3.     A 55-gallon drum filled with water or sand.

4.     A small ammunition can filled with sand.

5.     A cinder block filled with sand (block will probably shatter).

6.     A plate glass windowpane at a 45-degree angle (glass fragments may be thrown behind the glass).

7.     A brick veneer.

8.     A car body (5.56mm rounds penetrate but may not always exit).

As for the 7.62mm NATO ball it noted: “Barriers that offer protection against 5.56mm rounds are also effective against 7.62mm rounds with some exceptions. The 7.62mm round can penetrate a windowpane at a 45-degree obliquity, a hollow cinder block, or both sides of a car body. It can also easily penetrate wooden frame buildings.”

“Internal walls, partitions, plaster, floors, ceilings, common office furniture, home appliances, and bedding can be easily penetrated by both 7.62mm and caliber .50 [no shit, Sherlock] rounds.”

 

The following illustrations come from an experiment conducted by an Australian Army infantry officer. Building construction materials were engaged at various ranges, with one hundred rounds of 5.56x45mm ammunition linked four rounds of F1 (SS109) ball to one tracer fired from an M249 SAW and one hundred rounds of 7.62x51mm ammunition linked four rounds of F4 (M80) ball to one tracer fired from an M240B machine gun. Considering that the SS109 5.56mm achieves maximum penetration at 200 meters, the results of the hundred rounds fired against stacked bricks is particularly illustrative. At the same range, a solid block of non-reinforced concrete was engaged by each weapon, and the results viewed side by side are equally revealing.

Since all this information just shows penetration under ideal conditions, i.e. a perfect 90-degree angle on the bullet strike, perhaps more enlightening are the tests from the Jarheads’ technical training video Concealment Does Not Equal Cover.

The Naval Surface Warfare Center, at the Marine Corps’ Project Metropolis, conducted a more recent series of tests with current weapons against various commonly found wall/building materials, to include sheetrock, plywood, brick and cinder block. The ammo for the 5.56mm weapons consisted of M855 (SS109) 62-grain penetrator core ammunition; the 7.62x39mm AKM and 7.62x51mm weapons used standard FMJ (M43 and M80) ball rounds. All weapons were fired in 3-round bursts at the average urban engagement range of 19 meters, first at a 90-degree flat angle to the wall and then at a 45-degree angle.

I was a little surprised that the AKM did as well as it did and that the SAW didn’t do better. All the 7.62x39mm and 7.62x51mm weapons penetrated all media at all angles. The M16A2 failed to penetrate a single layer brick wall at 45-degree angle and also failed to penetrate a single layer cinder block wall at any angle. The M249 SAW with the same ammunition penetrated the brick and cinder block walls at a 90-degree angle but failed to do so at a 45-degree angle.

Target	90-degree angle	45-degree angle
Sheetrock	Yes	Yes
Plywood	Yes	Yes
Brick	Yes	Yes
Cinder Block	Yes	Yes

7.62x39mm Burst (AKM)

Target	90-degree angle	45-degree angle
Sheetrock	Yes	Yes
Plywood	Yes	Yes
Brick	Yes	No
Cinder Block	No	No

5.56x45mm Burst (M16A2)

Target	90-degree angle	45-degree angle
Sheetrock	Yes	Yes
Plywood	Yes	Yes
Brick	Yes	No
Cinder Block	Yes	No

5.56x45mm Burst (M249 SAW)

Target	90-degree angle	45-degree angle
Sheetrock	Yes	Yes
Plywood	Yes	Yes
Brick	Yes	Yes
Cinder Block	Yes	Yes

7.62x51mm Burst (M240B GPMG)

I’ve posted this before but I see that the old link doesn’t work anymore. Here’s a new link to the video over at Live Leak.

Watching this video should send a shiver down your spine. The military is always (supposedly) training to fight “the next war”. This meant that back when I was a Cold Warrior, MOUT training sites closely resembled the towns and villages of Western Europe, as we expected to conventionally fight “the next war” against massed mechanized Warsaw Pact armies pouring out of the Fulda Gap. Of course, we wound up fighting the next war in the open deserts of Iraq instead, but that’s beside the point.

Going by where the never-ending Global War on Terror has actually been fought since 2002, one might reasonably expect a modern military MOUT training site to resemble the architecture and lay-out of cities like Mogadishu, Baghdad, Fallujah or Kabul. Sarajevo or Grozny might also be possible candidates.

Instead, Project Metropolis doesn’t look like any city on foreign soil. With its red brick school, steepled white church on the corner, porched duplexes, green lawns, fire hydrants and stop signs, its looks a helluva lot more like Mainstreet, USA rather than anyplace in the Middle East or Southwest Asia. If the US military is training for the next expected war, then watching a conventional combined arms assault of heavily armed Marines supported by armor, helicopters and Harriers blasting their way down Mainstreet, USA should set off a couple of little alarm bells in the back of the American citizen’s mind.

So far you may be thinking this all falls under the “interesting, but so what?” category, but all this information has been put to good use militarily for decades. I’ve seen US Army WWII documents recommending the use of the commonly available .30-06 162-grain Armor Piercing round in the M1 Garand and Browning Automatic Rifle for combat in European forests specifically for shooting through trees used for cover by the Germans. GIs and Marines armed with the 7.62x51mm M14 in Vietnam commented on its ability to shoot through jungle foliage and tree trunks, as did ANZAC troopers armed with the L1A1 version of the FAL.

A still shot from the old US Army training film Infantry Weapons and their Effects. This is the moment of impact of a 150-grain FMJ .30-06 ball round hitting a bucket of water after penetrating an oak tree approximately 12 inches thick. Range: 100 yards. Performance of the 7.62 M80 ball is almost equivalent.

The Rhodesian Security Forces during the Bush Wars of the 1970’s really put the penetrative power of the “7.62 long” as they called it to good use with their Drake or Cover Shooting. This excellent article by “Ian Rhodes” which appeared in the Small Wars Journal is the best explanation of the tactic I’ve ever encountered and well worth the read.

An excerpt explains: “FAL 7.62 long rounds have the power to punch through the tree trunks generally found in the African savanna and jesse bush. AK47s using 7.62 short, on the other hand, generally did not. This fact was used to great effect by the Rhodesians. When firing into an area that included trees, rocks or ant hills etc, a single round down the left hand side of a solid object was good practice (not forgetting most opponents are right handed), then double tap the base of the tree and continue to the right, squeezing off single (or double) rounds in fairly close proximity. (In a conventional situation, moving from left to right takes out the trigger man before the machine gun loader or second.) Smallish rocks, strange “lumps” or “bundles of rags” were to be killed. In fact, anything out of place was to be dealt with—the “rocks” may be heads, hands, or a pattern on a camouflage uniform etc. The soldier then moved his aim to the next area of cover and repeated the process.”

The Rhodesians were tactically the finest light infantry the West has produced since perhaps the days of Daniel Morgan and there is a great deal to be learned from their common-sense approach. Consider that even when reserve policemen and farm guards are included under the overall umbrella of “Security Forces”, they still maintained an 8-to-1 kill ratio against an enemy who enjoyed staggering numerical odds and the latest Soviet and Red Chinese military gear. Well-trained crack units like the battalions of the Rhodesian Light Infantry Regiment achieved kill ratios on the order of 35-to-1 and sometimes as high as 50-to1. If shooting through cover worked for them I’m more than glad to do the same.

Beyond Africa, for a decade or more after the regular line infantry switched over to 5.56x45mm assault rifles, European nations which fielded elite mountain troops retained 7.62x51mm battle rifles for their special use. In mountain warfare, the long-range capabilities and wind-bucking abilities of the heavier caliber comes into its own.

Long after the rest of their army had switched over to the 5.56mm Steyr AUG, Austria’s Jagdkommando Special Forces retained their StG58 FAL-type rifles. In the event of a Soviet invasion of Europe, the Jagdkommando were trained to stay behind and operate behind the Soviet front lines. Under such circumstances, the Austrian mountain troops could sit back at 500 meters or so and engage Soviet support elements and security troops from beyond the effective range of return fire from their 7.62x39mm Kalashnikovs. Additionally, the 7.62 NATO’s heavier bullets and superior penetration were expected to prove more effective at disabling and destroying light wheeled vehicles and trucks, particularly with fire directed specifically against the engine blocks.

In urban areas the penetration of the 7.62 was also appreciated, as noted by a former British soldier.

“In places like Northern Ireland, if fired upon from a building’s window, fire was normally not returned at the window, but at the walls either side of the window. At likely places a firer would move to for cover. The SLR’s 7.62mm rounds could punch holes through brick walls. Many a surprised dead sniper (could he speak, that is) would testify to that fact.”

         On a whim, I decided to personally do a little informal testing of my own one day. I used some old British-style Figure 11 “Charging Commie” silhouette targets I printed out poster-sized, glued to heavy duty cardboard backers. There should have been more holes in these targets than there are, but I was playing with a Gat trigger device on the Century Franken-FAL StG58 that day. I'm pretty certain that rapid but aimed semi-automatic fire would have produced a lot more actual holes.

 Optics good, optics your friend. The photo was taken at approximately 75 meters, but the targets are hard to discern even at relatively short range.

 Where's Commie?

 Two of the targets were deliberately placed so that I would have to shoot through cover to hit them. One went behind some fairly serious cover; a mature Douglas fir with a trunk about 18 inches thick near the butt end had fallen over in a recent wind storm and I put the target fully behind it except for the head and shoulders. Engaging the target from 300 meters with an FAL shooting 145-grain Port FMJ, all rounds that hit the tree trunk penetrated fully with plenty of power left over to penetrate the target. One round blew out a sizeable chunk of wood that left a hole about two inches by inch in size through the Charging Commie as well.

 

 This wind-downed Doug fir looks like good cover, just over a foot and a half thick. This particular Figure 11 target was printed to be 18 inches across the shoulders for reference. At 300 meters, three 7.62x51mm FMJ rounds hit the log and all three fully penetrated it and the target.

The first picture didn't turn out, so this was a second Fig 11 perforated while behind the same cover with the same ammunition. Here the "exit wounds" in the tree are readily apparent.

A second Figure 11 was placed behind a large, flat rock that did not actually stand up high enough to provide true cover. More importantly, about 15 meters in front of the target was a sizeable standing Doug fir. From my firing position 300 meters away, the Figure 11 could not be seen except for a few patches of white color through the green boughs of the tree. Once more, the 7.62x51mm rounds made it through the boughs and limbs to hit the target. Two rounds hit low, striking the sloped surface of the flat rock in front of the target, and these produced a half a dozen long thin rock chips which themselves had enough velocity to slice through the cardboard. Even if these would not have been lethal against a human target, they no doubt would have made for a helluva distraction involving pain and blood flow.

Target #2 taken from 25 yards. The actual firing position was further to the left and required shooting directly through the tree boughs at what little was visible of the target.

          Red circles indicate bullet strikes while blue circles indicate rock chip "shrapnel wounds" from two low shots hitting the stone in front of the target (indicated by blue arrows).

          I actually considered the ability to shoot through fairly thick foliage the more important performance. British small arms expert Tony Williams explained why this is an important consideration: “Due to its small size, a 5.56 mm bullet can also be more easily deflected in flight on its way to a target. Thick vegetation, wooden posts and even soldiers’ web equipment have all caused 5.56 mm rounds to ricochet or bounce-off harmlessly, depending on the angle of attack. This tendency increases with distance and is again attributable to the rapid loss of energy at longer ranges.”

          Just for shits and giggles, I tried a "Rhodesian Cover Shoot" on the way home. A wolfy lodgepole pine with a bole roughly a foot thick alongside the abandoned logging road I was hiking became cover for a skinny Charging Commie. At an “ambush range” of less than 15 meters, I simply gave the tree trunk a double-tap from the FAL square in the middle of the trunk. The results in the photo pretty much speak for themselves.

Fig 11 Charging Commie before; he hides behind this lodgepole pine for cover.

Figure 11 Charging Commie after a 7.62x51mm ball double-tap to the opposite side of the tree trunk.

This penetration is something easily overlooked. No real hunter would ever shoot at game through foliage. In training, military MILES lasers, paintballs, Airsoft pellets and even Simmunition cannot support this type of shooting. In fact, I recall an NCO I knew whose solution to any tactical problem was, “Pop smoke, because MILES can’t shoot through smoke.”

Penetration is something you have to just keep in the back of your mind, and an occasional experiment like mine serves as a good reminder. Either that or you can tie a string around your finger.