7.62x39 Ballistics and Terminal Performance?

[LOKNLOD]

There’s a lot of discussion of the ballistics and terminal performance of 5.56x45. I’ve never seen much mention of the performance of the 7.62x39.

What’s commonly fielded? What’s its primary wounding mechanism? Is there anything it does especially well (other than feed and fire in Kalashnikovs), or a role it is particularly well-suited to?

Thanks.

[Jay Cunningham]

http://www.cs.cmu.edu/afs/cs/usr/wbardwel/public/nfalist/fl_aw_report2.txt

http://www.firearmstactical.com/images/Wound%20Profiles/AK-47%20762x39mm.jpg

http://www.btammolabs.com/fackler/wounding_patterns_military_rifles.pdf

[Heavy Metal]

Is there anything it does especially well (other than feed and fire in Kalashnikovs), or a role it is particularly well-suited to

Bust thru light cover, auto bodies and masonry. A good anti-sasquatch round.

[Cold Zero]

7.62 x 38 penetrates windshields well.

[BushmasterFanBoy]

It's primary wounding mechanism is penetration with side benefits of yawing, if your target is thick enough. For the most part, it is just like any traditional FMJ round. Being that it does not fragment, shot placement is more critical, but penetration and velocity concerns are no longer issues as well, its really a trade off.

[DocGKR]

In discussing 7.62x39 mm FMJ, the question is always which one, as their characteristics are highly variable.

There was a bit of a controversy brewing in some of the AAR’s coming in from OCONUS on the effectiveness of 7.62 x 39 mm ammunition. Initially, this appears somewhat strange, as there may be more forensic data available regarding wounds caused by the Russian 7.62 x 39 mm FMJ than for any other rifle cartridge. The original 7.62 x 39 mm Russian M43 Type PS 120.5 gr FMJ boat-tail bullet has a copper-plated steel jacket covering a large steel core and a typical muzzle velocity of 2340 f/s. In tissue, it typically travels approximately 9.8 to 10.6" point forward before beginning significant yaw. Most uncomplicated wounds of the torso and extremities have small punctate entrance and exit wounds and exhibit minimal internal tissue disruption since the bullet does not deform or fragment and usually exits before yaw occurs. Total penetration is around 29.1”. WDMET (Wound Data and Munitions Effectiveness Team) collected extensive forensic data on over 700 7.62 x 39 mm gunshot wounds during the Viet Nam war. The predominant feature of this cartridge is the MINIMAL amount of damage it produces in soft tissue wounds, on par with FMJ handgun wounds such as those produced by 9 mm M882 ball. We also have extensive law enforcement data, as this cartridge has been used extensively in illicit activity. For example, in the 17 January 1988 Stockton school shooting, 30 of 35 kids who were shot lived. Of the five that died, all were shot in critical structure--head, heart, spine, aorta and none had damage to any organ not directly hit by a bullet.

However, not all 7.62 x 39 mm FMJ bullets are of the original steel core construction. Significantly increased tissue damage is produced by the early yaw seen with several 7.62 x 39 mm FMJ lead core bullets, including:

-- Yugoslavian M67 124 gr FMJ, flat based, copper-jacketed, lead core bullet which travels only 3.5" in tissue before yawing

-- Chinese (PRC) 7.62 x 39 mm 123 gr FMJ, copper-jacketed, lead core bullets which begin their yaw after only 2 to 2.5" of travel in tissue.

-- Czech and several types of Western commercially produced lead core 7.62 x 39 mm FMJ yaw within the first 2 to 3 inches of travel in tissue.

In both uncomplicated extremity and torso wounds, the very early yaw of these lead core 7.62 x 39 mm FMJ bullets allow the projectiles to travel sideways through the body, substantially increasing permanent tissue destruction and temporary cavitation effects compared to the standard 7.62 x 39 mm Russian M43 Type PS 120.5 gr FMJ. These early yawing lead core 7.62 x 39 mm FMJ bullets cause wounds very similar to the 5.45 x 39 mm Russian M74 53 gr FMJ bullets, however, the larger size of the 7.62 x 39 mm bullets results in a bigger permanent cavity compared to 5.45 x 39 mm bullets.

The differences in terminal effects seen in recent combat with 7.62 x 39 mm FMJ wounds can likely be explained by the different terminal effects caused by the various types of FMJ construction.

When one moves to a expanding/fragmenting design in 7.62 x 39 mm, terminal performance is significantly enhanced. The best 7.62 x 39 mm loads we have tested to date are the Winchester 123 gr JSP (X76239) and the Lapua 125 gr JSP. Out of a 16” barrel they perform somewhat like lighter .30-30 loads:

Lap 125 gr JSP
Bare Gelatin: vel=2316 f/s, pen=17.3”, RD=.62”, RL=.43”, RW=122.6 gr
Car Windshield: vel=2323 f/s, pen=14.8”, RD=.60”, RL=.40”, RW=110.6 gr

Win 123 gr JSP
Bare Gel: vel=2253 f/s, pen=14.4”, rd=0.56”, rw=90.1gr
Pretty much the same results when going through car windshields.

Of note, most of the “cheap” Russian JHP/JSP ammunition offers poor terminal performance. The one that seems to work is the 7.62x39mm Saspan 124 gr JHP (Ulyanovsk Machinery Plant; 8M3 bullet); from a 16” AKMS the data is:

BG: vel=2297 f/s, pen=15.0”, Max TC=10cm@18cm, RD=0.63”, RW=100.5gr"

Because of the larger permanent cavity and greater bullet mass, the 7.62 x 39 mm JSP’s offer somewhat better performance than the .223 bonded JSP’s, like the Trophy Bonded Bearclaw use in the Federal Tactical loads. These 7.62 x 39 mm JSP loads are a good choice for use against car windows and should also be outstanding for hunting deer and other similar size game.

http://members.aol.com/_ht_a/docgkr/myhomepage/RussianWP.jpg

Of course, there are also Russian AP and API loads...

[LOKNLOD]

Excellent info. Thanks everyone.