PDA

View Full Version : Comparison of the 6.8 SPC to the 7.62X39mm


TimW77
July 15, 2012, 12:41 AM
Ballistics wise, how does the 6.8 SPC compare to the 7.62X39mm in an AR-15?

T.

jason41987
July 15, 2012, 01:01 AM
6.8 feeds reliably, 7.62x39 doesnt, the 7.62x39mm is a very tapered case, and because of this when stacked they want to arc more in the magazine, so a mag with more of a banana shape is neccessary.. 6.8 SPC is designed around the AR15 action, and isnt as tapered

RangerHAAF
July 15, 2012, 05:17 PM
7.62x39 doesn't feed well because the cartridge wasn't designed to feed in an AR type magazine. Rock River has addressed this problem by making an AR that uses AK magazines. This problem has always been the Achilles heel of trying to match the 7.62x39 round up with an AR platform.

I have owned ARs that shot both types of rounds and got rid of both of them. I'm on a waiting list to get the new Rock River LAR-47 that I mentioned above. From my reading and research I've concluded that the 6.8 SPC is ballistically superior to the 7.62 round as far as long range accuracy goes. The AK round will never be a tack driver but up close it can't be beat.

RT
July 15, 2012, 06:15 PM
What about 6.8 SPC versus 300 Blackout?


(duck and cover)

mehavey
July 15, 2012, 06:33 PM
...and the Grendel ;)

RangerHAAF
July 15, 2012, 07:22 PM
From what I've read they're all good cartridges but not in wide use. So unless the military starts widely using them they'll never get out of the starting block. So far at least only three bullet makers that I'm aware of produces the 6.8 SPC; Remington, Hornady & Silver State Amory.

I don't know anything about the Grendel or the 300 AAC.

OsOk-308
July 15, 2012, 08:00 PM
the Grendel is ballistically similar to the 6.8 out to about 400 yards, then its superior bc allows it to surpass the 6.8 past those ranges. (at about 1000 yards, the 6.5 even surpasses the .308). The 300 AAC blackout is an alright round as well, however, being a .30 caliber round, it's trajectory is not as flat, many people claim that it's maxed out at about 300 yards, it was originally built for suppressed weapons, and the power is close, but not quite equal to the 6.8

I love the idea of the 6.5, however, due to my budget restraints I went with the 6.8 SPC for my ar system, as the 300 aac didn't seem to be advantageous over the 6.8 in hunting of deer.

RangerHAAF
July 15, 2012, 08:05 PM
Do u hunt deer with it and if u do what's the terminal performance like?

jason41987
July 15, 2012, 08:29 PM
i did some ballistics research on the 6.8 SPC and 6.5 grendel, ballistics werent equal until about 800 yards out.. perhaps the grendel fans were testing their loads with the standard length 6.8mm bullet, however, i also tested the maximum bullet lengths for an AR15 type magazine in both tests i ran as well, SPC had a slight edge out to about 800 and the grendel only gained a slight advantage after that... see, what the grendel gains in a better ballistics coefficiency to conserve energy, the 6.8 has more to begin with, and only a slighter lower BC..

so if you compare that with the face the 6.8 feeds better in the magazines, has more of a capacity, and has a huge aftermarket backing (6 individual 6.5mm loads available on midwayusa.com and 30 available for 6.8) the 6.8 has the clear advantage

i too was also curious about the .300 AAC blackout, but wasnt too impressed with it ballistically, downrange its going to drop pretty fast, though it can take pretty long .308 caliber bullets, the overall velocity of the rounds negate the BC of the longer .308 bullets, with the heavier .308 bullets i see this being well suited with a suppressor and sub-sonic ammunition, for anything else i think it comes up lacking in all areas compared to the other options


my vote easily goes for the 6.8mm SPC for reasons listed above

mehavey
July 15, 2012, 09:11 PM
au contraire mon ami, the Grendel picks up the advantage almost immediately since it's 6.8SPC competitor
has the disadvantage of powder-limited capacity in the parent case. That means for the same useable
powder space under the 6.8's optimized 113gr bullet, I can put a 123gr 6.5 projectile in the Grendel.

(Try it in QuickLoad some time. The .277/115grSMK in the 6.8Rem and the .264/123grSMK in the
Grendel have exactly the same usable powder volume when seated to 2.25" for the AR magazine.)

The result is pretty much this:
http://i49.tinypic.com/m76c0n.jpg
http://www.alexanderarms.com/images/articles/shooting-times-d-fortier-article.pdf

Truth-in-Lending:
Granted, this is a Shooting Times article on the Alexander website, but my own Grendel performs exactly as advertised.

jason41987
July 15, 2012, 09:46 PM
sure it does, if you want to use a moderate 6.8mm load with the shortest bullet available, ive seen loads with close to 2800fps from the muzzle in 6.8 and if i was going to make a long range load i would use the 130 grain hornady interlock sst bullet, ive ran the numbers with different loads and found at 1000 yards, 6.8mm SPC and 6.5mm grendel were actually only about 50ft/lbs of energy different at 1000 yards and equal at 800, in a cartridge that actually chambers well, and has aftermarket support the 6.5mm grendel will never receive due to it requiring a single stack magazine and having feeding issues

if you want to go beyond 1000 yards target shooting, go for it, its not going to be useful for much beyond 800 anyway due to its velocity being way too low for expansion, unless all you were planning to do is scuff a metal plate.. face it, in a war between the 6.8mm SPC and the 6.5mm grendel, the grendel lost, the aftermarket has decided and thats why ill go 6.8mm SPC

mehavey
July 15, 2012, 10:46 PM
if you want to use a moderate 6.8mm load with the shortest bullet availableThe 113gr projectile provides the 6.8 it's max ballistic performance when having to balance
residual powder capacity against seating depth req'd of a AR platform (the OP's original question).
...would use the 130 grain hornady interlock sst bullet, ive ran the numbers...
6.5mm grendel will never receive due to it requiring a single stack magazine and having feeding issues...
Never had a failure to feed or extract in more than a thousand rounds.

Use of a 130gr bullet requires it being seated well beyond the 2.26" max length of the AR magazine
or you run into the same case capacity problem mentioned earlier. (In fact Hornaday 8th lists
their 130gr interlock/6.8Rem OAL as 2.355")

What does "single stack magazine" refer to? The Grendel uses a standard AR double-stack magazine design.
(In fact I once used my AR-15/5.56 magazines on a dare ...which functioned fine.)

TimW77
July 15, 2012, 10:56 PM
Let's try this again!

Question was, "Ballistics wise, how does the 6.8 SPC compare to the 7.62X39mm in an AR-15?"

Simple enough?:rolleyes:

No 6.5 Grendel, no .300 Blackout, no .308W.

No comparison of the 6.5 Grendel to the 6.8, no comparison of the Grendel to the .308W.

T.:rolleyes:

gun nut
July 15, 2012, 11:08 PM
The 6.8 spc is roughly 300 fps faster 200 more ft/lbs energy slightly more recoil energy. But similar recoil speed. Compared to 7.62x39. Hope that helps

jason41987
July 15, 2012, 11:32 PM
i would say in an AR platform, 6.8 delivers more power, more range, better ballistics, and is reliable in the forum, the 7.62x39mm ammo is cheaper to fire and provides sufficient performance out to 300 or so yards, but doesnt feed well due to the caper of the case.. HOWEVER, something like an AR47 lower receiver allows AK47 magazines to be used for more reliable feeding in the rifle, and i recon with a little skill someone could convert an AR15 lower to an AR47 lower and use AK banana mags for reliable feeding if you really wanted an x39 in an AR15

in a standard AR15 though, the 6.8 will function so much better hands down

gun nut
July 15, 2012, 11:48 PM
I have a 6.8 and am very happy with it's performance.

OsOk-308
July 16, 2012, 12:45 AM
The 6.8 spc is roughly 300 fps faster 200 more ft/lbs energy slightly more recoil energy. But similar recoil speed. Compared to 7.62x39. Hope that helps


Could not have said it better myself. Some people attempt to say that the 7.62x39 is close to the 6.8 (mistakenly). That 100-200 ft/lbs of energy is nothing to scoff at.

Also: my apologies for the comparison to the other two cartridges, I got carried away.

mehavey
July 16, 2012, 05:53 AM
Question was, "Ballistics wise, how does the 6.8 SPC compare to the 7.62X39mm in an AR-15?"
See the last two columns in the post #10 chart above:
http://thefiringline.com/forums/showpost.php?p=5148866&postcount=10


reference for most common ammo:
http://en.wikipedia.org/wiki/7.62%C3%9739mm

jason41987
July 16, 2012, 08:47 AM
something else it doesnt seem people realize, is surplus sources of cheap 7.62x39 is drying up, most countries that used that cartridge before havent used it in decades so it is running out, which means we'll be stuck with factory sources for this ammunition and the general cost to fire this round will be closer to the other common rifle cartridges in america... so the savings at some point are going to go away with 7.62x39mm

sgn100391
July 16, 2012, 03:24 PM
I have 6.8 and 300 blackout, but I like my 300 blackout better because I can go subsonic and supersonic, use my 5.56 brass and the magazines are plentiful. Not so with 6.8

LSnSC
July 16, 2012, 04:19 PM
Ive got an 6.8 SPC II that I built and have taken a fair amount of game with it.
The two best hunting bullets I have used are the 95gr Barnes TTSX and the 110 Nosler Accubond. I load both in Hornady brass over H322, seated to max magazine length, lit by a BR4 primer. They both give complete penetration and good expansion on whitetails and feral hogs. I shot a 100lb doe quartering to me and the TTSX smashed her shoulder and penetated lengthwise before embedding itself in her pelvic bone. Ive shot several 150-175 lb feral hogs through the front shoulders anchoring them on the spot. That told me everything I need to know about the cartridges real world performance.

Ive never shot a 7.62 x 39 weapon that impressed me enough to buy one.

FWIW I can find 6.8 SPC ammo in my local gun shops if needed. Ive never actually seen a box of 6.5 Grendel ammo for sale... anywhere.

mehavey
July 16, 2012, 05:29 PM
Ive never actually seen a box of 6.5 Grendel ammo for sale... anywhere.....
Both of my local GS's here in NoVa have it -- Clark Bros & Virginia Arms.
On the downstroke, I've never seen 6.8....
(then again, maybe I haven't looked) ;)

FWIW: When wolf starts producing a cartridge...
http://www.aimsurplus.com/product.aspx?item=AWG65Grendel&name=Wolf+Gold+6.5+Grendel+120grn+MPT+20rd+Box&groupid=247
You have arrived. :D



I now return control of the thread to the original topic.:rolleyes:
and beg forgiveness of the Moderators & OP.

jephthai
July 16, 2012, 06:12 PM
You'll never get the grendel and 6.8 people to live together. Such is life.

Anyway, I've been shooting my 6.8 SPCII in 600-yard F-class matches for a few months (I'm no good at it, but the round isn't the problem ;)). When you say "ballistically", right now I think of the curve. Run a few numbers, and you'll see that the 6.8 defeats the 7.62 fairly handily in the drop and energy department once you get far enough out. That 7.62x39 doesn't exactly have the best BCs.

Not like you're going to take a deer at 600 yards with 450 ft-lbs, but hey. It is a ballistic differentiator :).

I'm not running anything particularly hot, but my load gives me a max PBR (according to JBM) of 309 yards. For something that gives me more warm fuzzies (terminal-ballistically) than the 223, I feel pretty good about that.

jephthai
July 16, 2012, 06:18 PM
So far at least only three bullet makers that I'm aware of produces the 6.8 SPC; Remington, Hornady & Silver State Amory.

BTW, there are more than three now:


Hornady
Remington
Cor-Bon
SSA
Sellier & Bellot
Doubletap

Plus, there's a vicious rumor that Tula will be releasing an inexpensive FMJ in 6.8 SPCII sometime 'round the end of the year. Of course, the S&B is fairly inexpensive (comparatively speaking) these days already.

Praxisdorian
July 19, 2012, 12:44 PM
Mehavey, I saw the ballistics chart that you presented in a popular magazine. I thought the 6.8 stats in the chart seemed anemic from what I know about it. I found another chart that showed the 6.8 with the TSX 110 gr. While the muzzle velocity is nearly identical, the rest of the specs aren't. Bottom line is that the 6.8 110TSX is traveling @ 1439fps @ 600yds, not the authors stated 1287fps.

What we all want is a do everything weapon, and a lot of us hoped the SPC was close. The 6.5 Grendel is the perfect storm. It just happened to have the right BC for the velocity (~2700fps muzzle) and the typical "off the shelf" twists available. The 6.8 SPC suffers from the same issues the 7mm-08 did. In order to have the perfect BC per velocity/SD/Mass and all that sort of thing, you had to load a projectile that was too heavy to be safely propelled to that magic 2700 fps mark. And even if you could, you defeated your purpose anyway... that being... superior ballistics with minimal recoil.

I do believe that there is a perfect storm combination for the 6.8 also. But I think that it involves figuring out how to launch a ~130gr HPBT @ 2700fps with an appropriate twist to stabilize the bullet.

Just my .02

mehavey
July 19, 2012, 01:08 PM
"...figuring out how to launch a ~130gr HPBT [in a 6.6SPC] @ 2700fps with an appropriate twist..."
If we could do that [kick the .284's bullet weight up] we might get the improved BC needed to retain downrange velocity.

But we be faced with the same 6.8 problem we have now: the longer bullet in a cartridge whose OAL must be kept to the
req'd 2.26" magazine length would displace too much powder. We'd get better BC but at significantly lower velocity.

The Lord giveth, and the Lord taketh away.....
[If only we weren't stuck with magazine length.]

Praxisdorian
July 19, 2012, 03:05 PM
Tungsten core bullets would help with the OAL, but the only thing close I've found was the Barnes MRX with some sort of silver/tungsten core. Apparently, Big Bro assumes the worst about Tungsten.

LSnSC
July 20, 2012, 05:39 AM
The 6.8 does what it was designed to do, and does it well. It provides sustanitially more terminal energy out of the AR-15 carbine platforms, without substantial modifications. It was not designed to be a long range target / hunting cartridge. Medium sized game at 3-400 yds is its limit.

To get the most out of the 6.8 you have to have the SPC II chamber, proper twist and proper magazines that will allow you to seat the heavier projectiles a little farther out.

With PRI mags, and a White Oak SPC II barrel with 1 /11 twist I can get my loads out to 2.3" and not engage the rifling.

With the above specs 90-100 grain bullets can safely be driven to 2900- 3000fps, 110- 115 grain bullets can be driven to 2700-2800.

The Hornady 120 gr SST is the heaviest bullet I know of, that was designed to perform in the 6.8's velocity window. I haven't tried it. The TTXS and Accubonds performed so well, I didnt see any reason to.

Praxisdorian
July 20, 2012, 07:19 AM
Woodleigh makes a 130gr bullet with a 400+ BC and a length of 1.087", which is the length of a typical 110gr bullet. There may be others out there with similar dimensions.

I don't expect most 6.8 builds to be tack drivers. I do think that the 6.8 is very close in bullet weight and case capacity to being able to create that "perfect storm" that the 6.5 Grendel achieved with the 123gr projectile.

That being said, it may require some minor changes to the case (i.e. compound shoulder) to make that happen. I don't have the equipment as of yet to do such testing. It would be nice for someone that has the capability to see if it is possible to massage the specs of the SPC to be able to safely and reliably send a 130gr projectile downrange at 2700+ fps.

P.S. One of the reasons I like the 6.8 SPC is that it shares the same mags as the .458 Socom. For me, as an all around platform, the 6.8 and .458 seem to be the perfect combo for handling just about any situation (defense or hunting).

LSnSC
July 20, 2012, 10:26 AM
If the 6.8 SPC is properly built with a match grade barrel, and a good trigger there is no reason it cant be a "tackdriver".

With either the Accubond or the TTSX my rifle is sub MOA.

For match bullets the Hornady 110 HPBT and the Sierra 115 SMK are both sub MOA. I dont shoot many of either, as the rifle was intended to be a primarily a hunting / HD rifle. I have better platforms for long range shooting / hunting.

No need trying to put a square peg in round hole.

FWIW Grendel supporters always like to compare their best paper ballistics to the 6.8's worst. In reality there isnt enough difference to worry about. They are both good medium range medium game cartridges that will fit in the AR-15platform. That is their only reason to exist. Both are less than impressive when compared to more traditional hunting and long range target cartridges.

jason41987
July 20, 2012, 11:14 AM
6.5 grendel was designed for long range ballistics, to achieve this they sacrificed magazine capacity (having to single stack the magazines) and have problems feeding reliably due to the angle of the shoulder and its distance to the feed ramps.... so something that functions only for long range ballistics and fail in semi automatic, or assault rifle use is a far, far cry from a perfect storm

mehavey
July 20, 2012, 12:38 PM
"[6.5G] sacrificed magazine capacity (having to single stack the magazines) and have problems feeding reliably due to the angle of the shoulder and its distance to the feed ramps..." Where is this information coming from?

As already noted in posts above, the Grendel stacks in the same basic magazine design as the 5.56,
and in the same double/side-by-side manner to effectively the same capacity. **
(In fact I can use my other 5.56/M4 and HBAR mags in a pinch with no feeding problems whatsoever
to date.)

Have never had a single misfeed in now >1,200 rounds.

As to distance to feed ramps, it's no different than normal M16/M4 design (by definition) other
than being optimized for the case.



** Note stacking of Grendel's cases in the magazine below:
http://accurateshooter.net/Whitley/whitbigmag2.jpg

jason41987
July 20, 2012, 01:30 PM
in the 6.8 vs 6.5 grendel war, SPC won for a variety of reasons, the grendel isnt the "perfect storm" it was hyped to be, and in fact the 6.8 ESPECIALLY with newer SPCII chambers beats it out in a much more reliable, versatile cartridge... and the aftermarket proves its victory

mehavey
July 20, 2012, 01:37 PM
SPC won... It did?

Please elaborate.

jason41987
July 20, 2012, 02:31 PM
simple, compare the aftermarket, the aftermarket grows to suit a higher demand and absolutely dominates the grendel, ive done my own ballistics comparison and with SPCII loads and longer bullets available with under a 2.3" COL, they were nearly identical ballistically out to 800 yards

a cartridge thats ballistically only better between 800 and 1000 yards, which isnt going to have enough energy to kill anything larger than a rabbit, which also requires the use of a much longer barrel isnt a "perfect storm" but a specialized cartridge for post 800 yard benchrest shooting

for anyone actually wanting to do anything practical, the 6.8mm SPCII only requires a 16" barrel to achieve close to full velocity, be ballistically awesome out to 800, and actually be able to walk into a gunshop and find ammunition for it...

so the question is, how has the 6.8 SPCII not won?

all i see grendel fanboys use to drool over the 6.5 grendel with is outdated charts using outdated chamber specs and inefficient twist rates

TimW77
July 20, 2012, 03:03 PM
"P.S. One of the reasons I like the 6.8 SPC is that it shares the same mags as the .458 Socom. For me, as an all around platform, the 6.8 and .458 seem to be the perfect combo for handling just about any situation (defense or hunting)."

BS... It may work fine in a 6.8 mag but the .458 Socom uses STANDARD .223R magazines (although a slight modification is recommended).


"FWIW Grendel supporters always like to compare their best paper ballistics to the 6.8's worst."

And 6.8 supporters always want to rant about and compare it to the 6.5 Grendel regardless of the subject!

Whenever I looked at data from THE SAME RELIABLE and UNBIASED source, the Grendel is FAR SUPERIOR. But again the question is the 6.8 vs. the 7.62X39mm.:rolleyes:


"6.5 grendel was designed for long range ballistics, to achieve this they sacrificed magazine capacity (having to single stack the magazines)..."

As usual Jason, you don't have a clue and have it ALL wrong... The Grendel uses double stack magazines.


"in the 6.8 vs 6.5 Grendel war..."

Jason are you completely unable to comprehend anything?

This is NOT a 6.8 vs. 6.5 thread, READ IT AGAIN and then TRY TO comprehend it is a 6.8 vs. 7.62X39mm QUESTION. NO 6.5 Grendel, NO war.
Just read...


"ive done my own ballistics comparison..."

Yet you are so smart you can't even comprehend the question!!!:rolleyes:

Your inability to read/understand a simple question makes any of your supposed "research" worthless.:eek:

T.

jason41987
July 20, 2012, 03:38 PM
i didnt bring up 6.5mm, someone else did.. and i didnt test the best of one and worst of the other, i tested the best of both and the average of both.. but unlike the ballistics charts popular with 6.5 fan boys, i used loads tuned to SPCII chamber specifications and 1 in 11 twist rates.. so im not the one trying to sell the 6.5 grendel, but stated why the 6.8 is the best available in the AR15 platform

mehavey
July 20, 2012, 03:56 PM
all i see grendel fanboys use to drool over the 6.5 grendel with is outdated charts using outdated
chamber specs and inefficient twist rates....
Okaaaaaay.
That about does it for this discussion.

Acc371
July 20, 2012, 09:08 PM
Sorry for being late to the party!!:(
As for post #6 & #24:

As of 5/23/12

Barrett-------110 HPBT

BVAC---------110 VMax
--------------110 Accubond
--------------115 HPBT
--------------115 FMJ

Corbon-------110 TTSX
--------------115 SMK
--------------115 subsonic

DoubleTap-----95 TTSX
---------------110 Vmax
---------------115 FMJ
---------------110 TTSX
---------------110 OTM

Good To Go Ammunition
---------------115 OTM
---------------120 SST

Hornady-------110 Vmax
---------------110 BTHP
---------------120 SST

Hunting Shack-110 VMax
---------------115 OTM

RAM-----------110 VMax
---------------115 OTM

Rem.---------115 FMJ
--------------115 HPBT
--------------115 Corelokt Bonded
--------------115 SMK

Sellier&Bellot---110 TSX
---------------110 PTS

SSA---Loads available in Commercial and Tactical velocities
----------------85 ETip
----------------85 TSX
----------------85 Barnes RRLP frangible
----------------95 TTSX
----------------97 AP
----------------100 Nosler Accubond
----------------110 Nosler Accubond
----------------110 Sierra Pro hunter
----------------110 TTSX
----------------115 SMK
----------------140 Berger VLD

Wilson Combat
----------------95 TTSX
----------------110 BTHP
----------------110 TSX

Federal & Tula coming next year.

Post 7# The 300BO power isn't even close to the 6.8. Closer to the 7.62x39.

Post #10 HUUMMM.......A world class 123gr Lapua match grade bullet vs a 110gr hunting bullet. The parent case of the 6.8 is the 30 Rem(Rimless 30-30). Is that 123gr. 6.5G muzzle velocity Factory ammo? I'm looking at 6.5G factory loads & I don't see anything close to 2523fps. Because Wilson Combat factory ammo can push a 110gr 6.8 at 2700fps.

Post 20# The 6.8 can do subsonic too. See: above Corbon ammo & also check out Bison BSP. Yeah, the 5.56 does have allot more mag availability. But, it's not too hard to find 6.8 mags online. Eh, $12.00-14 ain't too bad for a magazine. Although, the 6.8 does have more expensive mags.

For post #26:
http://www.ssarmory.com/6.8_spc_ammo_140gr_VLD_Berger.aspx

Also, 6.8 can be loaded to 2.295-2.3 COAL (depending on mag [ACS/Stoner 2.295 & PRI & C Product Defense 2.3]). 2.6 is the outdated SAAMI limit.
Oh, C Product Defense Mags are 2.3 & are being shipped Monday. Allot cheaper than PRIs.

Post #34 He is talking about the number of 6.8, barrels/upper makers, ammo, mags & such. Plus, 85gr-14ogr effective bullet. It can be used as a Subsonic PDW or a hunting rifle 12.5" or above (16" being the sweet spot.). Now with the 140 Berger/SSA ammo, a long distance shooter.

TimW, take a chill pill!! Read post #5 about 6.6 vs 6.5. Although, I do understand your frustration. This shouldn't be a 6.5 vs 6.8 thread. Check out post #10. Also, the issue of the 7.62's firing pin/light strikes on certain ammo hasn't been brought up.
Oh, Hornady 6.8 120gr 16" barrel is 2460fps/1612ft-lb. With a 2.6 COAL & loaded to outdated SAAMI Specs. SSA has a 140gr 6.8 pushing around 2400 out of a 16" barrel. WC has a 110gr load going 2700fps w/ 16" barrel. All factory ammo. So, the 6.8 is still quicker than the AK round. If that is what your asking?:)

TexAg
July 20, 2012, 10:33 PM
Jason, just to be clear, when you say you've "tested" loads of both calibers, you've put them into a ballistics calculator of some sort? You don't own an AR of a caliber that's being discussed here?

jason41987
July 20, 2012, 11:24 PM
im actually building a 6.8mm SPC AR15 right now, i would have had a 6.8SPC ar15 sooner but im not one to run out and buy every new caliber that hits the market, i like to see the kinks get worked out first, such as already happened with the 6.8, and be sure there will be a future and an aftermarket for it, never considered a 7.62x39mm AR15 and i wont, there are just too many problems relating to the straight magazines, though, 7.62x39 would be fine if you had something like the AR47 lower

Praxisdorian
July 21, 2012, 06:10 PM
ACC371,

Thanks so much for the post!!!

I looked up the 140gr on SSA and the ballistics chart looks amazing! At least on paper, this is what I'm looking for. I spoke with my local dealer today about getting an LWRC M6A2 and will toy around with several loads, but especially SSA 140gr offering. That may just be close enough to the "perfect storm" for the 6.8 as it gets. I had thought 130gr would be the ticket, but the 140gr is very efficient. It would be interesting to see what the round would do out of a 20"DMR.

Thanks again.

tahunua001
July 21, 2012, 06:33 PM
alright let me give it a whirl. you are comparing 7.00x42mm to a 7.62x39mm. a lighter bullet, with a more aerodynamic design with more powder behind it is going to suffer less wind drift, bullet drop and loss of velocity than a heavier, more blunted bullet with a lighter charge. 6.8 is superior to the 7.62x39.

take that any way you want. 6.5 grendel 6.71x38 compared to 7.62x39. or 300 blackout, 7.62x35. the main difference is that the x39 has a tapered casing which makes it incapable of accepting higher pressure loads where as the straight case design of the 300AAC, 6.8 and 6.5 allows for greater charges possible. the 6.8 is the best combination of weight to charge ratio and is perfected by the fact that it has a decent bullet design.

mehavey
July 21, 2012, 07:01 PM
[6.8SPC] 140gr on SSA and the ballistics chart looks amazing!Can you give us the url of the chart you saw?
(Hopefully it includes barrel length)

mehavey
July 21, 2012, 07:16 PM
Never mind. Found it:
http://www.ssarmory.com/images/products/detail/140LRDrop_Table.3.jpg

In the tradition of my old 10th-grade English teacher, I now do a Compare & Contrast for reference. Note the 123gr Scenar:

http://i50.tinypic.com/14t2fjq.jpg

Note also: No special OALs, magazines or chambers....

;)

Acc371
July 21, 2012, 08:24 PM
Praxisdorian, your welcome!
The LWRC is a fine weapon! The 1:10 twist should stabilize it very well.
Oh, the min. opening of the 140gr is at 1800fps.
'The perfect Storm' will come at the 2013 SHOT Show. When Tula & Federal makes the official announcement of ammo release to the public.

Mehavey, it's still a 123gr vs 140gr. 79fps difference a the muzzle.
Eh, 1123.1fps at 1000y ain't bad for a 140gr out of a 16".
Not really a special COAL for the SPC II. It just the PRI & C Product Defense mags have a higher COAL allowance, as mentioned before. Both mags sold on Midway. ACS/Stoners will go to 2.295. Bolt action COALs will go longer .

mehavey
July 21, 2012, 10:52 PM
That's what makes a horse race, gentlemen. The 6.8 found itself in competition and pressed the envelope.

http://i45.tinypic.com/2hmfvp4.jpg

Now we'll see what the Grendel munitions folks do in response, having both a larger capacity/more efficient
case design to start with -- and higher BC for any given bullet weight. :D

Acc371
July 21, 2012, 11:27 PM
We will see what AA comes out with & what stats they publish?
Anyhow, the OP has nothing to do with the 6.5G

jason41987
July 22, 2012, 12:37 AM
its really not about the 6.8 or the grendel, its about the 6.8 vs the x39, which is simply blown away ballistically by either cartridge, the x39 just wont reliable feed in an ar15 platform, and since the surplus resources are drying up, its not even going to be useful for inexpensive ammunition anymore, theres every reason in the world to pass up the x39 (in the ar15 platform) and find something else, anything else really

TimW77
July 22, 2012, 01:09 AM
"Anyhow, the OP has nothing to do with the 6.5G"

"Acc371", exactly! No mention of the 6.5 Grendel (or .300BO or any other cartridge).


"its really not about the 6.8 or the grendel, its about the 6.8 vs the x39..."

Duh, come on Jason, if you know that why do YOU keep arguing 6.5
Grendel vs 6.8? Why do YOU want to make it a 6.5 Grendel vs. 6.8 war?

And it's not about any of the other BS you bring up. Simply a BALLISTIC comparison of the 6.8 and 7.62X39mm.

T.

mehavey
July 22, 2012, 01:44 AM
its really not about the 6.8 or the grendel, its about the 6.8 vs the 7.62x39...,Of course not. That was never even a debatable subject.
(Sorta like which is better, kerosene or the electric light bulb?)

It only got interesting when the string [effectively] turned to
"if not 7.62... then what's the best AR-based round?"

Then we began to learn things.

Acc371
July 22, 2012, 09:36 AM
I tried to get ballistics on the 7.62x39. I see the numbers. But, barrel length is not mentioned. There is a big difference between 16" & 24".

mehavey
July 22, 2012, 09:54 AM
tried to get ballistics on the 7.62x39. I see the numbers. But, barrel length is not mentioned.
There is a big difference between 16" & 24"
See post #10
http://thefiringline.com/forums/showpost.php?p=5148866&postcount=10

Acc371
July 22, 2012, 10:13 AM
DOH! Sorry, forgot about that.
Do you know if Silver/Brown Bear uses 24 or 16"?

tahunua001
July 22, 2012, 10:32 AM
most ballistics comparisons are done with 16 inch barrels. especially when you are dealing with the AK or AR based chamberings because the most prolifically used barrel lengths for them are 16 inches