precision ar build help, what caliber

JBrady555 · Jan 22, 2015

Hey folks this year's ar build will be of the precision variety. I want to be super accurate out to 600 yards with plenty of knockdown power. For fun I would like to use something other than 223. There is a lot of calibers I can build around that can still utilize the mil spec magwell, would love to here opinions on the best non 223 option for longer distances. 6.5? 6.8? I want to wax my buddies at our 200 yard hi power club matches but also have something that could serve a serious role should it ever be needed. I figured extra bullet weight couldn't hurt at longer distances, maybe less change in wind? A reliable cartridge is preferred and I will be reloading, so something with plenty of brass and bullet availability would be nice. Thanks for your opinion in this initial brain storming session. Right now I'm just looking at prs stock or other fully adjustable, good bipod, good glass, giessele trigger. Is the military using anything besides the 223 and 308 in the AR platform?

gotigers · Jan 23, 2015

For 200 yards you can get very accurate with .223 using heavy match loads or just about any caliber with match loads.

In the order i would prefer for serious 600 yard AR work.
DPMS GII .260
6.5 Grendel AR15
AR10 .260

edit: if you want to shoot F-class and stay F-T/R class, you will need to stay in .308 or .223. All other calibers are open class in F-class. Most of the very good open class shooters i've seen shoot 6mm BR bolt guns or similar.

rjrivero · Jan 23, 2015

If you're limiting yourself to a stock ar15 lower, then your answer is 6.5

There is nothing in that cartridge length that shoots flatter in my opinion.

stownsend · Jan 23, 2015

I am a fan of White Oak Armament.
They make a 6.8SPC II upper that might fit your criteria. I have their 223 20" varmint upper that is much more accurate than I am. Really challenges me to practice more and really see what the gun is capable of.

Darkbob · Jan 23, 2015

Both the 6.8 and the 6.5 can get you to 600 nicely. I think that the 6.8 is more common, but since you reload that's kind of moot. The 6.5 Grendel can use bullets with better BC that outperform the 6.8 at long range, however to get the most out of the 6.5 you should use a longish barrel (20"-24").

IF you want carbine length, the 6.8 has less muzzle blast and the performance will be pretty similar (between 6.8 and 6.5) out of the shorter barrel.

Honestly, up to 300 yards or so, performance is comparable regardless of barrel length. After 300ish yards, the 6.5 is pretty clearly the ballistically superior of the two.

With either 6.5 and 6.8, you'll need a dedicated bolt and mags.

JBrady555 · Jan 23, 2015

Thanks for the info. Looks like I'll be building a 20" grendal.

gondorian · Jan 23, 2015

That's a good choice. I'm very happy with mine

JBrady555 · Jan 23, 2015

gondorian said:
That's a good choice. I'm very happy with mine

What barrel manufactuer did you use?

gondorian · Jan 24, 2015

I got one of the barrels from midwayusa which are branded AR-Stoner and rumored to be made by Saturn. There was a whole hullabaloo about a year ago about the chambers being out of spec but I bought mine this summer and it is good to go. It's probably not the very most accurate barrel but I have had not problem shooting out to 500+ yards with it. It will hold below moa and easily blast clay pigeons at 3-400 yds. I do have a very nice trigger in it too. I got a geissele high speed national match 2 stage trigger and the money is worth it. It's the best trigger I've ever felt bar none.

Edit: I do have the 18" barrel which I decided on because I hunt with it and have found it to be a good size for the woods.

mnhntr · Jan 25, 2015

.264LBC/6.5 Grendel

brian923 · Jan 25, 2015

6mmx45 or 6mmbr if you want to be CRAZY with caliber choice. These dont fit your SHTF situations though because of ammo availability. But you could suffice that with a carbine .223 upper for apocalypse situations.

precision ar build help, what caliber

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