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View Full Version : Ballistic between 7.62 x 39 vs. 6.8


Lex
05-29-2010, 3:36 AM
Anyone have data between these two bullets going out of a 16" AR barrel? I am looking for something close range like less than 200 meters. I know 6.8 has some great results but the cost of ammo and availability turns me off. 7.62 is available in almost all gun shops/stores. (even Walmart carry this caliber) However, 6.8 would be custom order, online order or reload. So if i make my second AR with 7.62. How does it compare with 6.8 as far as performance?

scobun
05-29-2010, 11:39 AM
7.62x39 and 6.8 are very similar out to about 150 meters. Beyond that the 6.8 starts to shine because of the higher ballistic coefficient. The big difference is that the 7.62x39 ARs I've seen can't hold a candle to 6.8 in terms of accuracy, mostly because the vast majority of 7.62x39 ammo is crap.

Purple K
05-29-2010, 12:36 PM
6.8spc has about 80% of the power of the 7.62

scobun
05-29-2010, 2:24 PM
6.8spc has about 80% of the power of the 7.62

You've got that backwards. 7.62x39 is around 1500 ft.lbs. at the muzzle, while 6.8 is around 1800 ft. lbs. of energy.

reidnez
05-29-2010, 3:26 PM
Within 200 yards, the 6.8 is kind of wasted. Are you looking to hunt? 7.62x39 hits plenty hard at that range, more than adequate for deer or pigs (with proper expanding ammo, that is), and the accuracy is acceptable at that range as well. Cost savings will be huge.

killshot44
05-29-2010, 7:20 PM
They really don't compare very well. They 6.8 has such a fantastic profile and BC that it shines as an accurate round to over 600yds. But you aren't going to shoot much unless you reload (or you're loaded).

The 7.62x39 is not an accurate round owing to it's very low BC but given it's larger size, it has a good amount of grunt within 200yds, but 200 is stretching it, after that it drops like a rock. It's BC is barely over .200 while the 6.8 gets over .350.

Even if 7.62x39 ammo wasn't so cheap, few would bother to reload for it.

Everything you ever wanted to know but.....http://demigodllc.com/~zak/firearms/6.8SPC/faq.php

Jpach
05-29-2010, 9:57 PM
7.62x39 = 124grain-ish bullet at 2350ish FPS.

6.8 SPC can be 85 gr at 3100 FPS out of a 16". Or 110gr at 2750 FPS, or 100 at 2950.

Much better trajectory than 7.62x39.

Ya, its more expensive, but you should be handloading anyways.

If you dont plan on doing any hunting, then get the 7.62x39. If you want to hunt, the 6.8 is really a lot more versatile and cooler.

Purple K
06-02-2010, 1:23 PM
You've got that backwards. 7.62x39 is around 1500 ft.lbs. at the muzzle, while 6.8 is around 1800 ft. lbs. of energy.

I remembered the 80% quote from a write up in Shotgun News about two years ago. Upon reflection that was 80% compared to the 7.62 x 51.

Jpach
06-02-2010, 3:15 PM
personally i am not a fan of the 6.8 due to its high cost, lack of many rifles and generally not superior performance to other cheaper and more available rounds and rifles.

What do you mean? The Minis come in 6.8, a couple bolt action rifles come in 6.8, and there are quite a few AR manufacturers that make 6.8 rifles.

Here are just a few:

LWRC
LMT
Noveske
Wilson Combat
Bushmaster
Stag
DPMS
AR-15 Performance

And you can get uppers from lots of other companies too.

What cheaper rounds that are typically used in an AR platform outperform it?

I agree, the 6.8 spc ammo cost is not very cool. This is why it is key to reload, which we should all be doing anyways.

Lex
06-02-2010, 3:31 PM
I dont reload and dont plan on buying all those reloading equipment. So 6.8 SPC is way too costly for me to shoot.

NotEnoughGuns
06-02-2010, 3:40 PM
I really would like to do a 6.8 build but I just can't see any benefit over x39 for ranges I shoot at or might need to shoot at with a 16" gun with iron sights. If I wanted a target gun 6.5 would be my choice for an AR build.

I doesn't hurt that I'm sitting on a little bit of x39 already and have reloading equipment for x39.

Sniper3142
06-02-2010, 4:04 PM
The .308 is cheaper and more available and outperforms the 6.8 any day.

Yes, but in a much bigger platform (AR15 vs AR10).

For the AR15 platform, the 6.8 SPC II is a great round. There are standard .223/5.56mm rounds that have better long range performance. The 6.5 Grendel is one of the best long range performers in the AR15 but that is due partly to the projectiles with higher BC that are available. It is also harder to find ammo and components.

For overall use, it is hard to beat the 6.8 SPC II.

1988
06-02-2010, 7:21 PM
7.62x39 SP for hunting and Hornady V-MAX for defense and Wolf MC for SHTF stash. My favorite rifles for the 7.62x39 is the VZ.58 and the CZ 527

6.8 SPC if you're an AK hater... :D or being restricted to the AR-15 platform like the US military.

stormy_clothing
06-02-2010, 7:40 PM
Hands down 7.62 - first of all there is some hyper accurate rounds at those distances and it's cheaper so you can practice actually shooting.

Jpach
06-02-2010, 8:51 PM
Take any of the companies you mentioned and they offer about 15 .223 rifles for every 1 rifle in 6.8

Plus, most companies offer more .308 versions than 6.8

The .308 is cheaper and more available and outperforms the 6.8 any day.

Im not sure how many 6.8 SPC rifles you expect to be out there, but there are pretty much all practical types besides 24" varmint fluted with .750" thickness beyond the gas block. Not really sure where you are going with this, so many companies make rifles and uppers in 6.8 SPC and they are VERY available, I guess you didnt like the answer I gave :confused:?

And now that you brought up .308 rifles, look at Larue. IIRC there are only like a few barrel lengths for the .308 OSR. Why does that matter? Does the fact that Larue offers more setups in 5.56 make the .308 suck? Im not trying to attack you, Im just reall confused at the logic in your post.

The .308 certainly outperforms the 6.8 any day, no doubt, but it also beats the 7.62x39, and so does the 6.8.

Yes, the 6.8 is expensive, and yes, the 7.62x39 is cheap. But the 6.8 is quite a nice round for hunting and it does indeed offer better performance than the 7.62x39. To compare a 124 gr crappy russian bullet (or even a good hornady Vmax going faster) going 2350 fps to a very good 110gr bullet at 2750 out of a 16" barrel is just silly. If you dont plan on ever reloading, It makes sense not to go with the 6.8 unless you got money to blow. If you do, it really is a cool caliber to look into.

BTW, are 7.62x39 uppers even as plentiful as 6.8? Or as plentiful 5.56 for that matter? Honest question as I am ignorant to how common x39 uppers are.

Jpach
06-02-2010, 8:52 PM
7.62x39 SP for hunting and Hornady V-MAX for defense and Wolf MC for SHTF stash. My favorite rifles for the 7.62x39 is the VZ.58 and the CZ 527

6.8 SPC if you're an AK hater... :D or being restricted to the AR-15 platform like the US military.

Dude, that Wolf MC does some pretty cool ****. I likes.

j4strngr
06-02-2010, 8:52 PM
6.5 Grendel deserves a look

Sniper3142
06-02-2010, 9:07 PM
Hands down 7.62 - first of all there is some hyper accurate rounds at those distances and it's cheaper so you can practice actually shooting.

You must be talking about the 7.62x51 round.

Because Accurate and 7.62x39 do not belong in the same sentence! ;)

turbosbox
06-03-2010, 12:02 AM
Is the Wolf MC any different than the black box stuff? Other than a camo box?

Jpach
06-03-2010, 12:20 AM
Is the Wolf MC any different than the black box stuff? Other than a camo box?

It frags. Wolf MC HP, that is...

http://img361.imageshack.us/img361/2338/ulyhp0hc.jpg
http://i99.photobucket.com/albums/l308/MTMilitiaman/Guns/AKtests1.jpg

turbosbox
06-03-2010, 1:25 PM
thanks for the military classic response !
I did a search for myself function after asking, and I found a bit of info including the pic on how the MC fragments, but I wasn't clear on if the wolf blackbox HP also does. The second pic clears that up, as the blackbox is also 122gr as indicated, and MC HP is 124gr. The latter being shown in top pic.