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Old 07-24-2009, 03:13 AM   #1
allesennogwat
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Default US military 7.62x39 ammunition info

Commander in Chief Pacific Command History 1970 - Volume II, pp 259-260 wrote:

http://www.nautilus.org/foia/foiachr...eventyvol2.pdf

Assistance for the Cambodian Army

AK-47 Rifles/Ammunition

(TS) The U.S. and RVN began supplying FANK with captured AK-47 rifles and ammunition in April; however, an additional source was needed to meet FANK requirements. The remaining 1,420 AK-47 rifles were scheduled for delivery on 17 January 1971.2

(TS) On 31 December, Cambodia MAP was supporting a density of 68,973 weapons that fire AK-47 ammunition. After delivery of the remaining Indonesian AK-47s, the density will be 70,393 weapons. The 30-day ammunition consumption rate will be 8.73 million rounds. To provide a guaranteed continuing source of supply to meet the Cambodian MAP requirement for AK-47 ammunition, production is underway in the Continental United States (CONUS) under a contract paid out of Cambodia MAP funds. CONUS production was 20 million rounds for the period October through December. On 8 January 1971, the SECDEF approved CINCPAC's request to increase CONUS production to 9.5 million rounds per month. The first two million rounds of CONUS production AK-47 ammunition was airlifted to the RVN on 20 November. The first surface delivery arrived on 1 December with 5.96 million rounds delivered by 31 December. An additional 9.180 million rounds was scheduled to arrive by 13 February
1971.1

He stated that costs being equal, insertion of M-16s into Cambodia as the standard infantry weapon was much preferred to building a weapon system (AK-47) which was not U.S. supportable without parts engineering or tenuous third country support. However, additional AK-47 could be utilized provided they were procured at no cost to MAP and with no strings attached.

"U.S. 7.62X39MM Cartridge Development and Production (1968-1972)."

Two propellants were used in cartridge development at Frankford Arsenal.

124 Grain bullet 26 gr. WC680 and 26 gr. HPC2406 (or called HPC17) (RL-7?).

There were different cases used by Lake City AAP. Some were formed from a 7.62mm NATO cup, while others had a purpose made cup that ended up with with a 2 gr. larger internal capacity. While 26 gr. of WC680 was used for early testing, Frankford Arsenal switched off to a slightly lighter charge of 24.3-24.5 gr. of WC860 for the reference lots. Another interesting point was that the WC680 from Badger AAP gave higher velocities than that from Olin's East Alton plant. (Badger AAP was a GOCO facility run by Olin.) HPC2406 was tested, but dropped for excessive flash.


Specs supplied by Lapua.

Cartridge length 2.193" (-0.018")

Chamber pressure 45,000 CUP

Velocity 2275 fps @ 78 ft (+/- 30 fps) eq. to 2350 fps @ muzzle
(originally was stated as "Nominal 2200 fps")

Cartridge weight aprox. 279 grains
(originally stated as "aprox. 280 grains")


U.S. Military Specification Mil-C-70760
Ctg. 7.62x39 mm, Commercial
Dwg. #12598661

Bullet extraction force: 60 lbs. min.
Accuracy: 5.0" max. MR @ 200 yds.
Velocity: 2275 +/- 30 f.p.s. @ 78', Sd 30 max.

(eq. to MV = 2350 f.p.s.)
Chamber pressure: 45,000 psi (Cu) max. avg.
Cyclic Rate: 550-750 r.p.m. in AK-47/AKM rifles.
Bullet Wt. 124 grs., lead core with copper alloy
or gilding metal-clad steel jacket.
Primer: non-corrosive (Large rifle M34)


Frankford Arsenal developed the US military 7.62x39 cartridge specs but all production lots were made at Lake City Arsenal.
Not all of the ammunition was delivered to Cambodia. The left-over ammo was stored at a military base in Texas for many years. Also years later Lake City made a few more runs of 7.62x39 ammo for training purposes. Winchester WC680 is exactly the same as commercial W-680 powder which was pulled from retail sales due to low volume sales. WC680 and W-680 are faster than AA-1680. Winchester still uses it in 7.62x39 factory ammo loaded with 22.9 - 23.0 grains with 123 grain bullets. Maximum handload data was 25.0 grains with a 123 -124 grain bullet. I loaded 24.0 grains and it was fairly hot. As hot as most factory ammo. Too bad the powder isn't sold anymore. The Hercules Powder Company powder was most likely RL-7. It's claimed it was passed due to too much flash. It might have been some connections at Winchester for the exclusive contract though. Cambodia was getting some high quality 7.62x39 ammo from Lake City.
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Last edited by allesennogwat; 07-24-2009 at 03:19 AM.
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Old 07-24-2009, 04:53 AM   #2
ENGLISH MIKE
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Interesting.
I wonder how much 7.62x39 is currently being produced by the US.
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Old 07-24-2009, 12:24 PM   #3
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We will probably never know that.
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Old 01-03-2010, 06:25 PM   #4
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Accuracy - The average of the mean radii of all targets of the sample cartridges, fired in standard accuracy test weapons over a range of 200 yards, shall not exceed 5 inches.

Velocity - The average velocity of the sample cartridges, conditioned at 68 degrees to 72 degrees Fahrenheit (F), shall be 2275 feet per second (ft/sec) plus or minus 30 ft/sec at 78 feet from the muzzle of the weapon or 2350 ft/sec plus or minus 50 ft/sec at 15 feet from the muzzle of the weapon. The standard deviation of the velocities shall not exceed 32 ft/sec.

Chamber pressure - The average chamber pressure of the sample cartridges, conditioned and fired at 68 degrees to 72 degrees Fahrenheit (F) shall not exceed 45,000 psi (cup). The average chamber pressure of the sample cartridges conditioned at -65 degrees F and at 125 degrees F shall not exceed 48,000 psi (cup).

Headspace = 1.247" + 0.003"

(17 December 1990)

Alternate velocity/pressure barrel - For the velocity and pressure tests an alternate barrel used by SAAMI with the following dimensions may be used:

Overall barrel length = 20 inches
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Last edited by allesennogwat; 01-03-2010 at 06:33 PM.
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Old 08-12-2010, 08:45 AM   #5
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http://www.1919a4.com/forums/showthread.php?t=30226
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Old 08-13-2010, 01:28 AM   #6
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Cool thread - thx guys!
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