Help me with 7.62x39 or .308 in the AR

[bigalexe]

2 Things I should inform people of first; one being that this thread concerns a dream rifle that is beyond my current economic means so I am not going to go buy it tomorrow, and secondly there is another previous thread comparing the 7.62x39 and 7.62x51 cartridges specifically and so I am not trying to resurrect discussion of ballistics. As far as I am informed after read that thread the x51 has more boom.

I just discovered that DPMS makes an AR-15 chambered for 7.62x39 as compared to 7.62x51 (aka .308) is only available in the AR-10 platform. My question for discussion is how much difference in aftermarket will I see between the two platforms. My concern is that there will be a reduction in aftermarket variety of items and also an increase in price of stuff intended for the AR-10 as compared to aftermarket for the AR-15.

The intended rifle I would love to build is a long bull barrel either 20" or 24" in length with a suppressor (I live in Michigan sadly) or a muzzle brake if I can't get a suppressor when I get the rifle, chambering is at least a .30 caliber cartridge so it has enough power to put things down. The purpose is hunting white-tailed deer after a short walk from an ATV and long range practice so accuracy and power both trump weight in priority.

Considering this: AR-15 in 7.62x39 or AR-10 in 7.62x51

 

[rcmodel]

The .308 is a long-range hunting/target/fighting caliber.
The 7.62 x 39 is neither of the first two, and only a short range fighting caliber.

An AR-10 in .308 will feed 100% reliably, all the time.
An AR-15 in 7.62x39 will very likely not.

Think of the 7.62x39 as a 30-30 lever-action with pointy bullets.
Think of the .308 as a slightly less powerful 30-06.

Ammo choice for hunting or long range target shooting is very limited in the 7.62x39.
You have an almost limitless selection in the .308.

rc

 

[Col. Plink]

for hunting, I would think the AR10 in .308

-or save some big $ and get a Saiga308-v.21 with a good lookin' thumbhole stock and never look back.

 

[R.W.Dale]

I agree with the above posts. The vast platform and cartridge charistics really rule out any meaningful comparisons. About the only common aspects are aesthetics and a somewhat 30 caliber bullet diameter.

 

[NG VI]

Light .30-30 by the way.

 

[Afy]

Your want a .308 buy a FAL. A 7.62x39 buy a AK/Vz. You want an AR stick with .223 or if you must .222.

 

[wally]

I really like my 7.62x39 AR, but magazine issues keep it a range toy only, which is a shame.

The AR10 style rifles are very nice and while significantly more powerful, are also significantly heavier and more expensive to shoot.

 

[Col. Plink]

a buddy is building a 7.62x39 AR, is he going to experience feed issues?

 

[bigalexe]

Thanks, I knew that .308 had more boom but didn't know it had THAT much more boom. That's why I ask these questions.

 

[R.W.Dale]

a buddy is building a 7.62x39 AR, is he going to experience feed issues?

With some of his mags to some extent most likely.

 

[wally]

a buddy is building a 7.62x39 AR, is he going to experience feed issues?

Mine was a jam-o-matic with the C-Products 30 round mags until I put the spring from a real AK (Bulgarian steel) mag in it. So far its been good since, but only about 300 rounds through six different mags (with changed springs). Way better than the couple of stoppages per mag I was getting. The 10 rounder has always worked.

I really enjoy shooting it, just haven't had as much time as I'd liked and we've had so much rain the past few days probably won't be able to get to shoot until next week at the earliest

 

[NG VI]

I would love a 7.62x39mm AR, though I'd rather have an AR designed around a case about the same width as the x39mm, but straightish-sided, and pushing a slightly slimmer/heavier for caliber bullet, notably faster, maybe a 7mm Demonic name it. Now that it's on the internet that name is copyright by the way. Ill.

Who cares about the loss of five or so rounds capacity? At that economy of space and weight, good Lord would that be a cartridge to contend with. COuldn't do it. Be like 9x19mm (great cartridge, so many practical advantages and applications) vs .44 Magnum (good number of advantages, many applications that either overlap or outpace 9mm, but can never replace 9mm for what it is), it would be like running a 12 round .44 Magnum with not too much more recoil over the traditional 15-17+1 round 9mm.

 

[benEzra]

In my opinion, 7.62x39mm is too tapered to feed well through an AR-15's straight magwell. AK magazines are smoothly curved, and they really need to be due to the geometry of the cartridge.

IMO, if you're wanting a little more oomph than .223 in an AR, something like 6.5mm Grendel, 6.8mm Remington, or .30 Remington AR would be better (although the latter would probably require that you reload your own ammo, until availability goes up and prices come down). All three are ballistically superior to 7.62x39mm and will feed fine through an AR-15 magwell, though all are considerably pricier than 7.62x39mm, .223/5.56x45mm, and 5.45x39mm.

Also, unless you reload your own, there is precious little 7.62x39mm ammunition available in the United States that is truly accurate. If you were in Finland, it'd be a little easier to come by, but here, not much of the really good stuff is imported, and bullet selection is extremely limited. 7.62x39mm is also a relatively short-range cartridge, due not only to the relatively low muzzle velocity, but also to the short and draggy bullets. It drops below the 1000 ft-lb threshold, often considered the threshold for a humane kill on deer-sized game, after only 125 yards or so.

 

[Col. Plink]

then it seems like an AR in .243 would be gangbusters.

Am I right?

 

[R.W.Dale]

then it seems like an AR in .243 would be gangbusters.

Am I right?

No cause a 20" 243 is just a loud glorified 30-30 in terms of ballistics. Unless you plan on building a long barrels 24"+ target rig there are much much better cartridge choices that offer the ballistics to take advantage of the AR10 magwell

 

[Tirod]

The problem with the x39 is the tapered case,which requires a curved mag. The AR15 magwell is straight. The AR10 mag well is straight, too, but usually uses a straight magazine.

Capacity isn't a major issue, hunting medium game means toting less than ten rounds, and that is actually mandatory in a lot of jurisdictions. It helps solve the problem, as most 10 round mags don't have the curved section that causes the feeding problem.

Ballistics is a large part of the decision, tho, as they are not interchangeable rounds. A longer look at the trajectory and amount of power at various ranges needs closer review. It's not very different than asking whether .30-30 or .30-06. The difference in actions between them is more pronounced, but the same kind of consideration goes, too. The calibers have different power levels and can't be shot from the same gun.

 

[GIJOEL]

In my opinion the 7.62x39 in the AR is far more useful than what it may seem. Both DPMS and now Bushmaster are making rifles chambered in 7.62x39, the low cost of the ammo, and increasing interest in accurate and lethal ammunition is slowly starting to get manufacturers to get us the "good stuff". My x39 carbine is set up as a dissipater and I can keep 10 rds on a 6in paster at 200 yards. The Ar-10 platform is awsome, but by the time you build a 20in rifle in .308 (or anything else) and put a scope on it it's going to weigh 9-10 lbs if your lucky, my x39 is a sneeze under 7 lbs and handles smartly. As for feeding, the x39 was designed to feed well, just not in the AR. After I spent my first range trip hand cycling my AR I got home and had to take off the barrel and re-shape the feed ramps, since then I've had 600 trouble free rounds through it and all seems well. And finally the magazines, I have had good luck with the 10 and 30rd C-products mags, I wonder how many people who have feed problems with these mags also have M4 feed ramps still contoured to 5.56mm.... The 7.62x39 and the .308 are very different rounds and when in the AR-15 and AR-10 separate even further in terms of capability's and there niche in the firearms world. I built mine because I hunt in thick woods where a light rifle with accuracy and power for a 200 yard shot is everything that I want. If I hunted on the edge of a cornfield with 600 yards to the next tree line then things would be different.

 

[rangerruck]

Lets say, all things being equal, cost is your #1 requirement.
x39 ammo is back down to logical levels. Lets just say 5 bucks a box of 20, that is with tax. 308 is still 15 bucks a box, but for craps and giggles, lets say, next year it gets back down to 10. Lets say for sake of arguement, you fire on avg., one box of ammo per week, for all 52 weeks a year. that is 260. a year on x39 ammo, and 520 a year on 308 ammo. And that is if 308 goes back to 10 bucks a box....

I would seriously consider a remmy/bushmaster in 30AR, which will be a 30 cal bullet, fired from a 308 caliber cartridge, say , with a tad less powder. it will be doing about 25/2600 fps, from the muzzle, and it comes in a true ar 15 package, not an ar 10 package.

 

[Quiet]

Main problem with 7.62x39mm ARs is the magazines.
There has yet to be a reliable 7.62x39mm AR magazine.
Only reliable magazines I've ever experienced were the Colt 7 round magazines (it's the size of a 20 round 5.56x45mm magazine).

The magazine problem is why some manufacturers have made AR lowers that use AK magazines. The MGI MARCK15 seems to the more reliable of the AK magazine AR15 systems.