6.8
Recently I have been thinking about a 6.8 for my AR. Is it worth it or should I just get a A-10 for a higher grain round? How flat is the trajectory on the 6.8. Is it as good as a 7mm mag? What is the drop at 100/200/400 yards. If its a good investment why didn't the Miltary adopt it as a cheap conversion. How hard is ammo to come by? Any help appreciated. Thanks
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pigfarmer05,
Welcome to the Gunbroker Forums!
Here is some reading for you to do regarding this cartridge:
http://demigodllc.com/articles/6.8-mm-spc-cartridge-history-development-hornady-stag-arms-carbine/
http://www.shootingillustrated.com/Ammo/Rifle/6.8SPC.html
http://demigodllc.com/~zak/firearms/6.8SPC/faq.php
http://www.frfrogspad.com/68spc.htm
"Is it worth it or should I just get a A-10 for a higher grain round?"
I think you mean an AR10 and yes, that would be my suggestion if it's between just these two cartridges.
"Is it as good as a 7mm mag?"
Not even close. Read the articles above as they have all the charts you need to answer your questions.
Best.0 -
I'm no expert on the 6.8 but will share my experience so far. Bought one with a 20 inch heavy barrel which was an easy add on to my Colt SPII lower. Factory loads cycle well but I'm having a little trouble with reloads which I'm sure will be worked out. No, the 6.8 is nothing close to a 7 mag. Think 110 grain bullet at 2550 fps versus a 140 at around 2900+. I'm pleased with the performance relative to the 223 but it will never be a 7 mag or 308 for that matter. Ammo is available but not everywhere; found four boxes of Hornady factory in a pawn shop in Amarillo this weekend for example. However, Cabelas in Fort Worth didn't have any. . .or any bullets for reloading. Midway and other web retailers have ammo and reloading components. Not sure why the military didn't adopt it but suspect that their conclusion was that it just wasn't that much better than the 223 for general tactical operations. They have a number of specialized weapons to choose from when something beyond the 223 is needed. If you want something dramatically more effective than the 223 buy the A-10. If you want something different and fun to shoot, and effective on small and medium game (including white tails), the 6.8 shouldn't disappoint. 0 -
I have 2 6.8's and I would not trade them for anything very good deer hunting cartridge with a lot less recoil then the .308 but I like that cartridge as well. Cabela's does stock 6.8 ammo and bullets for reloading its just a hit or miss as to when they have them. You can order on line from Silver State Armory they have the largest selection of 6.8 out of every one. The first two guns in my signature line are 6.8. The first is an Armalite and the second was my most recent build an all CMMG gun. As far as why the Army won't adapt it is the same reason why they don't go to a gas piston gun. There not in the inventory per say and it would cost to much to retro fit all the AR's in the field. Remington had also announced some new loads for this year and Sellier & Benoit also have a load or two. The ammo is out there you just have to look for it. I had one of the first 6.8 builds in the country nearly 3 years ago and believe me there's a ton of ammo for it now compared to then. To answer your other question a 308 is no where near as flat as shooting as a 7mm mag so the 6.8 is no where near it nor would be the .308. 0 -
Someone with experience in the mountains of the middle east put it to me this way. Want to hit a target at 800 yards with an AR platform? Get a 6.5. Want to kill the enemy out to 4-500 yards? Get a 6.8! Want to kill the enemy farther than 500 yards? Go with a 308. Sounded like good advice to me.
And i have a LMT CQB in 556 and 6.8, and love it. I'm not trying to bad mouth it at all.0 -
quote:jeffb1911
Member
USA
638 Posts
Posted - 04/19/2010 : 12:40:09 AM Show Profile Email Poster Reply with Quote
Someone with experience in the mountains of the middle east put it to me this way. Want to hit a target at 800 yards with an AR platform? Get a 6.5. Want to kill the enemy out to 4-500 yards? Get a 6.8! Want to kill the enemy farther than 500 yards? Go with a 308. Sounded like good advice to me.
And i have a LMT CQB in 556 and 6.8, and love it. I'm not trying to bad mouth it at a
Well said, they all have there purpose.0 -
pigfarmer05,
I would agree that jeffb1911 put if very well. The 6.8 is an improvement over the 5.56 in the AR platform for a more lethal punch out to 500m. That was it's intent. Think of it as more 5.56, not as a .308 in a AR-15 platform. That can be done but at a very limited capacity. Notably the WSSM series of cartridges.
Personally, I went back and forth on deciding on a 6.8 SPC or a 6.5 Grendel. I found both to have adequate power/speed, but not great. Both could shoot lighter bullets such as 85 and 90 gr. relatively flat (around 2900 fps speed). The big crux for both cartridges was having enough barrel. In short barrels, 16", it took a rainbow trajectory to get a bullet to 300. Both perform much better with 20"-24" barrels.
In the end I decided on the 6.5 for these reasons:
a)You can get very high BC bullets in 6.5 caliber. The 123 gr. Scenar surpasses M118 (7.62 NATO sniper ammunition) at around 600m. By that time the best useable 6.8 bullet is now falling off more rapidly than both the 6.5 and the .308/7.62
b)Even if you could get 6.8 bullets with the same BC as the 6.5's (which is possible, Mfgr's. just don't make them yet) you couldn't seat them out where they need to be to fit and function in a magazine.
c)I only lost one round of capacity (25 in 6.5 vs. 26 in 6.8) in a 30 rd length 5.56 mag. However, both the 6.5 and 6.8 really do require their own mags to feed properly. Simply changing the follower can make it work...but not as well.
For what you are asking the 6.8 is a VERY viable drop on upper for the AR-15 platform. As noted there are other options but you would have to decide what your final product needs to be. Do you need to shoot to 1k? Is 500 enough? How much energy do you need? In that category there is almost no difference in the 6.5 and 6.8 out to 400yds. Of the other options I've found that the 6.5 Grendel is expensive. But, it's non-licensed likeness, the 6.5 Sporter, not so much. 6mm AR and AR Turbo same. Nothing more than a 6PPC improved.0 -
How does the 6x45mm fit in this discussion?
Same brass, same magazines, same magazine capacities, good 6mm bullet selection, better wind bucking and 200ft.lbs additional punch. There is no other change to the AR except the barrel.
That's like adding the power of a 38 Special to the 223.0 -
quote:Originally posted by v35
How does the 6x45mm fit in this discussion?
Same brass, same magazines, same magazine capacities, good 6mm bullet selection, better wind bucking and 200ft.lbs additional punch. There is no other change to the AR except the barrel.
That's like adding the power of a 38 Special to the 223.
v35,
6x45 is a little bit of a jump in power. Simply because you have more bullet area to push on than the .223. But the thing you are really faced with it is that you still can't get the super high BC bullets into one and feed them through a magazine. If you just wanted to slam 85/90's out there then this would be a very viable answer.0 -
I had a 6mm/.223 for years and took some deer with it all where 1 shot kills. It was a decent cartridge for what it was an upgrade from the .223. Then I upgraded to the 6.8 and didn't find a need for the 6mm/.223. I certainly didn't need AR's in 4 calibers. Sold the upper dies and all the ammo to a fellow in Washington state. 0 -
I have a few 6.8 uppers, both carbine length & rifle length barrels. I have had pretty consistant groups and reliability from them all so far... from what I have seen with the lighter upper, the recoil of a hot loaded 115 OTM is about twice what it is from a comparable weight upper in .223 with 55 grain bullet..
Performance on deer has been just as good as what I have had with a .223 and 7.62x39, but the exit hole is larger with the 6.8 then the .223 and the noise of the bullets impact in noticable louder on steel.
If you wanted a handy AR rifle for med range medium game and coyote hunting the 6.8 is a good choice.. but as sandwarrior points out the better BC and sectional desnity of the longer 6.5 bullets offset the itermediate velocities slightly.
but in my opinion if you want flat trajectories from an Ar-15, look into a .223WSSM or .243WSSM or .25WSSM chambered upper.0
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