6.8 or 5.56 precision AR

WestKentucky · Jan 10, 2016

I am at an odd crossroads on an AR build. I built my lower thinking it would be months before I did anything else, but I came into a few other bits and pieces really cheap, so now I am almost to a completed rifle. I have the complete lower which still needs a better trigger, but it has a functional trigger in it. I have a complete doublestar 6.8 spc upper that only needs bolt and BCG to complete the build...but I have no dies, brass, ammo, etc. On the other hand I have a 5.56 barrel with gas block, dies, brass, bullets, powder. I'm trying to decide which way to run and complete this thing so I can do some shooting.

Here's the poop on the stuff....

Have section.

6.8 rem spc (factory built upper, new but display model has minor scuffs)(220 bucks out the door by the way)
Doublestar complete flattop upper
Doublestar free float knurled tube type forend
Doublestar gas block
Doublestar heavy stainless rifle length barrel, 6.8spc 1:10 target crowned

5.56
Unknown maker, 20" hbar profile match grade barrel, target crowned
No-name gas block
Everything to reload
Pmags

Don't have section...
6.8
Correct mag followers for pmags
Bolt carrier group
Reloading dies
Brass
Bullets

5.56
All the other parts of the upper (would strip 6.8 and build 5.56)
Bolt carrier group

I'm kind of at a loss here. Please give me some advice on which way to run with this build. Whichever I build first will be followed by the other next winter. This gives me time to build funds up to buy all the other stuff I need for the other caliber, not to mention 400 dollar scopes, 200 dollar triggers, and reloading stuff for the 6.8. I know I'm cheaper in it to run the 5.56, but is it worth tearing down the upper to do so and hope for the best on an unknown barrel? I can't decide, when I think I have decided I second guess myself on which I want now.

Food for thought is attached.

crazysccrmd · Jan 11, 2016

You'll need to find out if that 6.8 barrel is a SPC II chamber. A 1:10 twist, 6 groove will not let you get the most performance out of it and a SPC I chamber would make it worse. You will also need 6.8 magazines, you can't just swap followers from a 5.56 mag, especially a pmag.

bfoosh006 · Jan 11, 2016

IMHO... I would build the 5.56.

The 6.8 is a great round... just not really known for long range.

The 5.56 has numerous advantages... the biggest being speed of a good BC bullet.

WestKentucky · Jan 11, 2016

Been pondering this pretty much all day. I think I'm going to build the 5.56 now. That gives me time to try to find deals on brass and dies for the 6.8. I still am shaky about that decision, but I think it's going to stick.

Malamute · Jan 11, 2016

What are you lacking in 5.56 that the 6.8 has? You mentioned taking own the other upper, you don't have a spare upper receiver? They aren't very expensive, and you'll eventually need another one.

dirtengineer · Jan 11, 2016

If it were me, I would probably build both of them! So the question should be, which do you build first?

If you hunt or want a more powerful carbine for whatever reason, go with the 6.8. Else, go with 5.56 first.

WestKentucky · Jan 12, 2016

dirtengineer said:
If it were me, I would probably build both of them! So the question should be, which do you build first?

If you hunt or want a more powerful carbine for whatever reason, go with the 6.8. Else, go with 5.56 first.

The plan all along has been to build both, but not at the same time. I do hunt, and do want a more powerful rifle, but the barrel on the 6.8 is so heavy that it will not be packable in the woods, and cannot be shot easily without a rest simply because it is so front heavy. The 6.8 will be built, but it will be a paper puncher. It's only hope to be anything else would be to get it reprofiled to shed at least a yhird, maybe half of its weight.

adcoch1 · Jan 12, 2016

Profiling the 6.8 to make it balance better for hunting is a good idea IMHO. 6.8 has most of its value in a hunting rifle due to the heavier hitting bullets and proprietary magazines. Balance is probably more important than weight in an ar hunting rifle anyway, so find a lathe and go for it.

mokin · Jan 12, 2016

I really like my 6.8. Accurate and launches a bullet twice as heavy as what you normally shoot out of a 5.56. Also, it's legal to hunt with in Colorado. From the list of parts it looks to me that the question is, "Do you want to get the project done and go shooting, or do want to build a while?"

For the 6.8, you'll need many more parts, and in the scheme of things a new upper is a relatively minor thing. If you want to go out and shoot, go for the 5.56.

d2wing · Jan 12, 2016

I would go with the 5.56. It is a high energy round that works very well on deer size game. Anything bigger I would go with the 6.8. You aren't going to like a heavy AR hunting, unless you hunt from a stand with a rest.

Dean1818 · Jan 13, 2016

If you are going to hunt, I would do the 6.8. I use it for the Texas pigs.

I made the same choice a few years back and love the stopping power of the 6.8. I used an awesome Bison Armory upper

Additionally, there are some awesome bullets for the 6.8

I use a 120g Hornady SST.

It gets 1k ftlbs out to 275 yards. Every animal I have shot has dropped on the spot except one. (It went around 15 ft)

You could use this bullet for hunting until you bought your reloaders equip.

I wouldnt hesitate to shoot at game to 300 yards with this bullet. (This is about the limit of the distance I would go anyway)

There are also now some cheaper plinking bullets that you could start to shoot to build your brass count

Good luck

ArchAngelCD · Jan 14, 2016

I would not strip that upper only because I need a bolt, brass and dies. I would go with the 6.8 since its a more versatile hunting round. While the 5.56 "can" be used on deer I wouldn't use it but would not hesitate with the 6.8 SPC. You can always buy a complete 5.56 upper later for not a lot of money. Midway USA has complete 5.56 AR uppers for $299 including the BCG including the bolt.

MistWolf · Jan 14, 2016

Build what will get you up and shooting the soonest

WestKentucky said:
...the barrel on the 6.8 is so heavy that it will not be packable in the woods, and cannot be shot easily without a rest simply because it is so front heavy...

If the 6.8 barrel is that heavy, sell it and get a lighter one.

Build your 5.56 first. Removing and replacing a barrel in an upper is easy

6.8 or 5.56 precision AR

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