7.62x39 FAQ
Last Updated :: 2/23/2010 2:41:09 PM EST
7.62x39 FAQ


Link to Wikipedia Entry with Cartridge Dimensions and History

Q: Where Can I find a Chrome Lined 7.62x39 barrel?
A: Armalite offers 7.62x39 ARs with chrome lined barrels. Rumor has it the new Doublestar barrels are chrome lined as well.

Q: Can I use AK-47 Magazines?
A: Depends on the Lower used. MGI makes a modular lower (magazine well is changeable from AR to AK), Also, there was a run of lowers (AR-47) that could take AK magazines made by Special Weapons, and another by Vulcan. Both of these required a slight modification to the upper by dremel to allow the AK magazines to fit, and use of a modified bolt carrier.

Q: What kind of lower do I need?
A: Any AR-15 lower can be used for AR-15 type 7.62x39 magazines.
If you want to use AK magazines you'll need either:
  • MGI lower with the AK magazine well
  • AR-47 lower (made by Vulcan, and orginally by Special Weapons).

Q: What kind of Bolt Carrier do I need?
A: Any standard AR-15 bolt carrier can be used for AR-15 type 7.62x39 magazines. If you want to use AK magazines you'll either need to machine out the lower grooves (to fit the AK magazines feed lips), or the MGI bolt carrier which is already set up for AK magazines.

Q: Do I need the extended (M4 type) feed ramps?
A: While they are not required, if everything (magazine, upper, lower) is not perfect you can have feeding issues. The M4 feedramps help greatly with reliable feeding. From canon3825:

Some geometry to think about. With an unaltered carrier whatever magazine is installed is limited in height by the bottom of the carrier. The 7.62X39 round is larger in diameter than 5.56X45. So the top of either round is up against the top lips of the magazine. The 7.62X39, having a larger diameter, will have its center line lower, compared to the center line of the bore. Since the center line of the 7.62 round is lower, there would need to be a deeper ramp because the round starts further from the center line of the bore.

I have done the same modification that you have pictured to my three 7.62X39 uppers, which has greatly improved feeding reliability. I used a small diameter stone to blend the steel barrel extension to the aluminum upper extended feed ramp. I would highly suggest that you use some rubbing compound and polish the feed ramps. I also noticed that the sharp top edge of each ramp would put grooves in the round as it was chambered. I used the same small diameter stone to round the top edge of the feed ramps and then polished them for smoother feeding.

Q: What kind of buffer do I need?
A: Either the Rifle or any of the standard carbine buffers will work fine.

Q: Can I shoot surplus 7.62x39 in these rifles?
A: Depends. Some people have issues with 'surplus' due to the hard primers. The AR-15 firing pin isn't quite long enough. The usual fixes are either a stronger hammer spring, or taking 0.005"-0.007" off the tail end of the bolt to allow the firing pin to reach the right protrusion length for 7.62x39; or by putting the firing pin in a drill and use a file to take that much off the face of the flange. MGI produces a bolt and firing pin combo optimized for eastern European steel case ammo.

Q: Do I need to reload with .311 bullets, or can I use .308?
A: .308 bullets generally work fine.

Sources for Rifles:
  • Olympic Arms (16"; 1:10 twist, threaded 1/2x36, 416 Stainless)
  • Double Star (16" & 20"; threaded 1/2x36)
  • Sabre Defense (14.5" & 16"; 1:10 twist, Chrome Lined, M4 Profile Avail)
  • Armalite (16"; 1:10 twist, Bore .311, threaded: 5/8x24, Chrome Lined, M4 Profile Avail)
  • Colt (16"; 1:12 twist, rifles no longer in production)

Sources for Complete Upper Assemblies:
    • Model 1 (11.5" sold as a pistol upper, 16", & 20"; 1:10 twist, threaded 1/2x36)

      Del-Ton (16"; 1:10 twist)

      DPMS (has had them in the past)

      MGI (16"; 1:10 twist)

      J&T Distributing (16"; 1:10 twist, HBAR)

      Bushmaster (16")

      Colt (16" & 20"; 1:12 twist, not in production but can be found from time to time)

Sources for Barrels or Bolts:
  • Model 1 (Barrels & Bolts)
  • Olympic Arms (Bolts)
  • Del-Ton (Barrels & Bolts)
  • DPMS (Barrels & Bolts - occasionally)
  • MGI (Barrels & Bolts)
  • J&T Distributing (Barrels)

Sources for Brass:
  • Winchester
  • Lapua

Typical Performance: (courtesy of Krochus)

Muzzle Velocity:
123gr FMJ (Monarch)........16": 2344fps....20": 2426fps
125gr SP (Remington)......16": 2224fps....20": 2300fps
154gr SP (Wolf)...............16": 2031fps....20": 2115fps

Ballistics:
123 grain Monarch FMJ, ballistic coefficient .257

range........elevation........velocity........energy

16.5" bbl

100yds........+3.44"........2042fps........1139 fpe
200yds........+0.00"........1765fps........850 fpe
300yds........-14.72".......1517fps........628 fpe


20" bbl

100yds........+3.12"........2118fps........1225 fpe
200yds........+0.00"........1833fps........918 fpe
300yds........-13.74".......1578fps........680 fpe

125 grain Remington SP, ballistic coefficient .267

range........elevation........velocity........energy

16.5" bbl

100yds........+3,93"........1941fps........1046 fpe
200yds........+0.00"........1684fps........787 fpe
300yds........-16.15".......1454fps........587 fpe


20" bbl

100yds........+3.57"........2012fps........1124 fpe
200yds........+0.00"........1747fps........847 fpe
300yds........-15.02".......1510fps........633 fpe


154 grain Wolf SP, ballistic coefficient .330

range........elevation........velocity........energy

16.5" bbl

100yds........+4.64"........1813fps........1124 fpe
200yds........+0.00"........1614fps........890 fpe
300yds........-17.78".......1432fps........701 fpe


20" bbl

100yds........+4.20"........1891fps........1223 fpe
200yds........+0.00"........1685fps........971 fpe
300yds........-16.39".......1497fps........766 fpe


Q: I've heard the 7.62x39 is ballistically similar to the .30-30, but how close can I really get it as it normally uses lighter bullets?
A: Courtesty of Krochus

LOL 30-30wsm in a way that's really how you can look at the lil russan round. Or at least in the case of my Model1 20" 7.62x39 upper

Today (28-Sept-2008) I was shooting handloads, 170grn Sierra FP's originally intended for 30-30win over 29grs of H335 for an avg velocity of 2020 FPS.

Accuracy was OUTSTANDING and oddly enough feeding was flawless as well.

For a comparison I shot some factory 170grn Rem ammo through my 20" pre-64 Winchester M94, velocity averaged 2175 for this load and accuracy was nowhere near as good. appx 4" at 100yds for 5 shots

(http://www.jobrelatedstuff.com/forums/topic.html?b=3&f=121&t=397166)



Q: Are there any sub-sonic loads for the 7.62x39?


Q: How should I zero a 7.62x39?
A: Given 123gr FMJ (common steel cased), 16" barrel, and the AR-15's 2.6" height over bore the following might be useful:
@25 yards, far zero: 249yards. Max Height 6.1" @ 143yards
@ 27.3yards, (25meters) far zero: 235yards, Max Height 5.1" @136yards

Best (closest to replicating 5.56 IBSZ)
@ 35yards, far zero: 190y Max Height: 2.6" @120y, +/-2.6" from muzzle to 250y.
25y: -0.7"
50y: +0.9"
100y: +2.5"
200y: -0.9"
300y: -15.9"

Q: How can I modify my stock 7.62x39 bolt and firing pin to reliably fire surplus ammo?
A: Courtesy of MikeinGA

1. File .010 of an inch off the back of the bolt.
2. Put the firing pin a drill motor.
3. Put med. lapping compound on the firing pin and put the pin into back of the bolt and run for 30 sec. Do this step four times.
4. Clean bolt and pin.
5. Do step 3 but use metal polishing compound. Do this step 3 times.
6. Clean bolt and pin.
7. Do step 2 and use a rag and metal polish and polish the pin.
8. Goto Wolff Spring Co. and get XP Hammer Spring.


Another option courtesy of BMAX

I chucked my .223 firing pin up in a cordless drill and took a hand micrometer and measured the thickness of the pin where it meets the bolt face,I then took a finishing file and slowly removed .007 off that face and have had no problems with misfires what so ever.



Q: Can I use 6.5 Grendel magazines?
A: Courtesy of LRSNutJob

I purchased a few of the first generation 6.5 Grendel mags from C-Products to see if they would work. They actually do work though the gentleman at C Prod said they had problems with them and did not guarantee it.

The biggest thing was that it only loaded 22 to 24 rounds and you had to raise the front part of the feed lips as the rounds tended to nose dive into the front of the mag. I fired probably 500-600 rounds thru these mags to get them to work with 100% reliability. I had 100% reliability in firing with Winchester ammo and probably 1 round in 20-30 where it was a light primer hit with OLD green box Norinco ammo (it was given to me). At the time I was unaware of the primer issues with the imported ammo.

Sources for RELIABLE magazines:
  • C-Produces (5, 10, 25 {1st gen} & 30 round {2nd gen}stainless magazines)
  • MWG (5 & 10 round plastic magazines)
  • Scherer (30 round hybrid magazines - AR top AK bottom)
  • G-Tech(30 round hybrid magazines - AR top AK bottom)
  • Colt (these were 20round 5.56 magazines with a 7.62x39 marked floor plate and a metal strap riveted in to limit the magazines to 5 rounds, no longer in production).

Info from Boomer:

Magazine have always been the Achilles heel of the 7.62x39 AR-15.

Pretty much any USGI 5.56 magazine will work reliability with 5-6 rounds of 7.62x39. After that, the cartridges begin to bind up and jam.

Colt first used regular USGI 20 round magazines with internal blocks to limit capacity to 5 rounds of 7.62x39. These internal blocks were easily removed after which the magazine would function just like any other USGI 20 round magazine. After the ban they switched to a cut down USGI style magazine feed tower with a unique composite base to prevent them from being converted back into 20 round magazines in violation of the AW ban at the time.

Because the 7.62x39 AR15 appeared relatively shortly before the AW ban and never really gained much popularity in that time, development of high capacity magazines for it was limited. While there were some stamped sheet metal magazines from companies such as Triple-K, Western, USA, etc, the only ones worth a darn were what are essentially hybrid magazines; AR15 style feed towers welded or riveted to AK47 style bodies. Scherer and Gordon Technologies magazines are the most robust of the preban high capacity magazines. These are aftermarket steel AR towers TIG welded to genuine AK47 magazine bodies with similarly genuine AK47 springs and followers. Surprisingly, despite otherwise having a reputation for total crap, USA had some good high cap 7.62.39 AR magazines that used their own AR style steel feed tower spot welded to their proprietary AK style body, spring and follower and they work very well.

Here is a pic of the various types of 7.62x39 AR15 magazines Boomer has collected over the years:



Top row, left to right: MWG 10 round, Colt post-ban 5 round, Colt pre-ban 5 round.
Bottom row, left to right: Scherer 30 round, G-Tech 30 round, USA 20 round, USA 30 round.


The Scherer and G-Tech mags are nearly as robust as an AK47 magazines. One could probably drive nails with them if necessary.