AR15 .. 5.56NATO or 6.8SPC?

[pipmaster1971]

So I'm mulling my options to build my AR15 and am wondering if I should go the 5.56NATO route or the 6.8SPC? Does anyone have any opinions? An initial glance of prices seem like the 223/5.56 ammo prices are much cheaper. But I will do most practice on my M&P 15-22 (a great gun, got it last week - lots of fun), and only bring out the big brother on special occasions.

Another question: I know I need the upper to match the ammo used, but what about the lower? Would a lower be agnostic towards 5.56mm / 6.8SPC? Or do I need a dedicated lower for each caliber?

 

[PatMcD]

Unless you had a great desire to own a 6.8, I see no real need for it. Ammo is more expensive and hard to find, greater recoil, inferior long-range ballistics, etc.. It makes a dandy deer hunting round, if hunting with an AR is your thing.
Any standard .223 lower will accept a 6.8 upper.
If you want a larger caliber in an AR but don't want to move up into the .308 size, consider a 7.62x39 upper. Cheap ammo.

 

[Bob P]

5.56 = plentiful, fairly cheap rifle ammo that will be available from several different sources if you are in extremis.

 

[drgrant]

If you have no intention of reloading 6.8 SPC don't even bother with it. It's too stupidly expensive to consider running otherwise.

-Mike

 

[bullseye]

5.56 is much cheaper to shoot, more fun time at the range as you have stated, but if the AR is your prime weapon for home defense, your going to want tp practice with it. Granted the 22 is cheaper to shoot, it in no way is a representation of the 5.56 recoil/ability to acquire target after a shot is fired. Also if your going to be shooting at anything over 50 yds, your going to want to practice with your go-to weap, not a 22. Good luck hitting a man sized target at 2-300 yds after practicing with a 22.
Hell, if SHTF and you need to find ammo, 5.56 is going to be a little easier to come acsoss than 6.8. Also, green tip AP 5.56 is going to be a better bet for hard targets/technicals rather than a 6.8. If you are interested in the 6.8 for longer distance/terminal capability, go with 6.5 Grendel. 6.5 at 500+ yds will hold a flatter trajectory than 6.8 and has more energy retention than a 6.8, also the 6.5 is about twice the mass of a 5.56
The lowers are the same.
If you can, get both uppers, 5.56 and a 6.5 Grendel and be prepared for anything, Zombies are toast at 600 yards.

 

[pipmaster1971]

5.56mm it is then

 

[crazymjb]

If it was a SHTF weapon for mainly CQB or urban crap I would still say 5.56 despite the ballistics on the 6.8 SPC. Simply put, its so much more plentiful you'll have a much easier time acquiring it if in need. If you want a bigger round, get something in 308. More plentiful and cheaper still. Also a superior round.

Mike