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orb451
09-29-2009, 2:43 PM
Hello all, I'm a newb and I'm looking to put together an AR chambered in 6.8SPC. Ammo prices seem to be pretty decent for this caliber, am I wrong in thinking that this would be a good caliber to go with for long range shooting (300-500+ yds)? I was going to get a 24" upper, do I need anything special for the lower in terms of sizing or will the typical 5.56 lowers work fine?

It's also my understanding that the mags are different for 6.8 and that's fine by me as well.

Any info or recommendations are appreciated. I intend to mainly use this for paper punching between 100 - 500+ yards, non competitive shooting and would like to "possibly" use it for deer / small game hunting.

Thanks again!

Rich.

THT
09-29-2009, 2:45 PM
Same lower as 5.56 and yes, the mags are different. For the longer distance, I would suggest 6.5 Grendel over 6.8SPC. however 6.5G is more expensive for both components and ammo.
And you didn't ask but the other different parts are the bolt and barrel.

CHS
09-29-2009, 2:57 PM
6.8SPC was designed SPECIFICALLY as a short-range cartridge to deliver more energy. It was not designed as a long-range cartridge, so why would you want to use it as one?

twang35
09-29-2009, 4:19 PM
Head over to 68forums.com. Tons of info on that site and it will answer all your questions.

gun toting monkeyboy
09-29-2009, 4:24 PM
6.8 SPC is a ballistic twin of the old .257 Roberts cartridge. It would be fine on deer out to about 250 yards, with the right bullet. It is probably effective well out past that, but with a light-weight bullet like that, I wouldn't push it.

-Mb

PaulS
09-29-2009, 4:46 PM
Hey Rich, listen to THT and Twang35. I'm in a process of building up 6.8SPC myself after having a chance to shoot my buddies. The trajectory is very flat it is just as accurate as 5.56 but has a bit more energy and knock down punch. The price of ammo came down in the last 6 months and the caliber is becoming more and more popular with recreational shooters as well as hunters (pig, white tail).
For upper look into http://www.titanarmory.net/ or http://www.ar15performance.com/

Super Spy
09-29-2009, 5:26 PM
Another good reference is Snipers Hide, I found a real good thread on 6.8 there http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1212721
I'm planning on a 6.8 build myself and I've been doing lots of research. 6.5 Grendel was suggested as well but the ammo is more expensive and much more difficult to find and I don't reload (yet) plus there are many more 6.8 uppers to chose from. Pay attention of the chamber and twist rate as some 6.8 barrels have the older chamber (originial Remington design) and this will limit the performance of the gun. I will probably go with AR15performance or White Oak Armament on my build.

Desert_AIP
09-29-2009, 8:10 PM
6.8 SPC was designed to be fired from short BARRELED rifles, not necessarily short range.

It gives better terminal performance with the same or better accuracy as 5.56 at all ranges.
THAT is what it was designed to do. It's certainly has better long range performance than a true short range cartridge such as the 7.62x39.

The longest distance available at my local range is 350 yards, and I can hit a 6" steel gong all day long at that range.

A 110 grain 6.8 out of a 16" barrel has the same velocity and thus the same POI as a 75 grain 5.56 out of a 20" barrel at all ranges out to 600 yards.
An 85 grain 6.8 has a much higher velocity (~3100fps) and thus less drop out to the same range.
I've never shot it further than 350, but I'm estimating from JBM calculations that 600 yards is pushing the limits of this cartridge, I'd try to stay inside 500.

6.5 Grendel is flatter because it uses higher BC bullets, but to acheive the higher velocities needed for that trajectory you need a long ~24" barrel.
Most 6.8 velocities are quoted out of 16" barrels, so it's hard to do an apples to apples comparison.
Since you want the longer barrel, know you'll get a couple hundred fps increase from a 24" 6.8SPC over the values I quoted above.

6.5 components and ammo are harder to come by than 6.8.

For top 6.8 accuracy you will want to use PRI magazines. They let you load to ~2.30" OAL. That really improves accuracy over the ~2.26" limit of CProducts and Barret magazines.
I've been having great results from a lowly 16" lightweight barrel firing 110gr BTHP loaded to 2.30". Some sub MOA groups when the wind is dead.
I have an 18" SPR barreled rifle built waiting on glass that I'm confident will return even better results.

For hunting,
85gr Barnes TSX wilf fly through a hog producing DRT results out to 300 yards.
110 Sierra ProHunters or Nosler Accubonds are perfect for deer. If you need lead free the Barnes 85 will work here too.
110 Hornady Vmax are perfect for coyotes and CQB/Home defense with Speer 90gr TNT a close second.
I like the Hornady 110 BTHP better than the Sierra 115 SMK for target shooting at longer ranges.

orb451
09-29-2009, 9:54 PM
Thanks guys for all the info. I'm not into reloading (yet anyway) and ammo cost is a concern when adopting a new platform caliber. I was thinking 6.8SPC might be a good fit for long range and understand what you guys are saying. Maybe for laser accuracy out to distance I'll have to suck it up and go the 6.5 Grendel route. Only thing about that that threw me off was all the different size cartridges. If you buy a 6.5MM rifle upper will it (within reason) work with all or most 6.5MM cartridges?

Thanks again for all the info!

Rich.

CHS
09-29-2009, 10:55 PM
Only thing about that that threw me off was all the different size cartridges. If you buy a 6.5MM rifle upper will it (within reason) work with all or most 6.5MM cartridges?


Not sure exactly what you're asking about.

What matters is what you're chambered for. If you're chambered for 6.5 grendel, you'll be able to fire 6.5 grendel and nothing else.

orb451
09-30-2009, 7:10 AM
Yes that's where the confusion was for me, the 6.5 Grendel vs. 6.5 Lapua, etc. The fact that if I go to the ammo engine website as an example and see 6.5MM Creedmore, 6.5MM Japanese, 6.5MM Carcano and so on. My understanding is that each one is a 6.5MM bullet with a different casing size / dimension / shoulder. I was trying to figure out if you get a 6.5MM rifle and it doesn't explicitly say Grendel or whatnot, what rounds would work in it and how to tell what to expect.

B Strong
09-30-2009, 7:20 AM
So far I've been able to ignore the siren's call of the 6.8spc or 6.5G, but I have fired my cousin's LWRC in 6.8spc and it's a good unit, and the cartridge has potential.

In checking out the ballistic tables, it's clear that the 6.5G is the more ballistically efficent of the two, and if you're after long range accuracy and effectiveness the 6.5G is the way to go.

Sky_DiveR
09-30-2009, 4:11 PM
The 6.8SPC is designed specifically to burn efficiently in a short (16" or less) barrel. Going to a 24" won't get you more than acouple of hundred FPS. How far were you planning to shoot?

Talk to Tim @ Titan Armory or Harris @ AR15 Performance for the best advice. They are the ones getting the manufacturers to change from the incorrect specs by Remington and are getting much better performance out that round than when initially introduced. Actually if you're from CA, you'll be dealing with Harrison @ AR15 Performance. Tim handles the other side of the Mississippi(?). Both use the same uppers/custom barrel.

Drop by 68forums.com and check out the specs. Ask a few questions... the group there is very knowledgable. The Specs for the 6.5 are impressive but the round is a high pressure round with a bullet with a high BC to get those ballistics. Out to +600 yards using one of AR15 Performance uppers, it can hold it's own against a 6.5G. Again check out the specs, ask questions, and decide on your own. You can also drop by Adams' site, 6.5grendel.com... he's the designer of the round/platform.

ar15barrels
09-30-2009, 4:19 PM
Yes that's where the confusion was for me, the 6.5 Grendel vs. 6.5 Lapua, etc. The fact that if I go to the ammo engine website as an example and see 6.5MM Creedmore, 6.5MM Japanese, 6.5MM Carcano and so on. My understanding is that each one is a 6.5MM bullet with a different casing size / dimension / shoulder. I was trying to figure out if you get a 6.5MM rifle and it doesn't explicitly say Grendel or whatnot, what rounds would work in it and how to tell what to expect.

A barrel is only chambered for ONE cartridge.
You have listed many different cartridges.
Of all those cartridges, ONLY the 6.5 Grendel is available in an AR-15 upper.