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Posted: 1/5/2013 4:37:06 AM EDT
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I've been seriously considering building a 6.8 upper lately, and I have some questions. I'm not looking at starting out shooting off gnat's whiskers, just figuring out the round and how it works in ARs, so sub MOA at 1000 yards is not something I'm looking for. For a shooter versus a bench rest gun, is there a need to hold out for a stainless barrel, or should a chrome lined barrel work for me? Polygonal rifling - just cool, or useful/important/crucial? What are the benefits of going longer than 16" with a barrel? Why does Remington use large primers in their ammo while SSA uses small primers? Which mags are best?
Thanks for the insights. |
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I'm no expert but I'll chime in on a couple of your issues. First, the 6.8 is not a 1000 yard cartridge, in fact propably not even a 500. The good bullets have a BC similar to the good match .224 bullets so if your goal is longer range match shooting I'm not sure there is much benefit to going with 6.8. Of course if you want more energy at distance for a hog or deer, then 6.8 does beat 223/5.56 at all distances.
Barrel choice is the same as any other round. If you want sub MOA, then a premium ss barrel may be a good choice, if you want "practical" accuracy in the 1 to 2 MOA range, a cl barrel should get you there, at least for a couple hundred meters. Best magazines are Barrett and PRI. I've got a few of the new c products defense 25 rounders that are supposed to be good but I don't know if they are yet. If you hand load pri mags allow for a longer coal than Barrett. I got a 18" barrel for my rig but my next one will be 16" or 14.5" as I Found very little velocity advantage with the extra two inches. Ar15 performance claims his cust spec barrels out-perform longer standard barrels in terms of velocity. If really true that would be where I would try next, if supplies ever catch up before the regime turns half the law abiding country into pseudo criminals. |
6.8 really shines in the shorter barrels. I have a 16" and 12.5" 6.8 barrels and I've thought about dropping the 16". I use AR15performance barrels and bolts so I can hand load to maximize velocity. Unfortunately I haven't been able to run my 12.5 upper yet and won't be able to until I get back from Afghanistan |
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The 6.8 will do 1000 paper or steel. Especially, with factory SSA 140gr Berger ammo or reloads of 120SST, 110 Accubonds. But, there are better calibers for that.
SS, chrome lining or even meloniting is personal preference. Chrome & meloniting will add barrel life. So is 3-poly. 16"+. Really not much, except 25-35fps per in (A recent article has the new Federal 90gr ammo has it at 18.75fps/in). Remington was the first to produce 6.8. Other studied it & felt the SRP would handle more pressure & longer case life before primer pockets expands. Especially, in hot loads. The 68forum is a great place to find 6.8 info & more. Oh, Barrett mags only load to 2.26. ASC/Stoner = 2.290-5, PRI- 2.3, CPD 2.295 -2.305 (depending on version.) |
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I have a 20" rifle that is almost done.
I went with 20" because I wanted a DCM type build for this 6.8. Not so much for added performance, if any. 16s and 18s are very popular. The barrel is a melonited ARP which I believe is amongst the best 6.8 barrels. Harrison @ ARP is on the bleeding edge of 6.8 development. Bison would be another that I would entertain for a 6.8 barrel. The most popular mags are PRI and CPD. SSA and Hornady are best for store-bought ammo and for brass. Remington ammo has the undesirable LRP and is underpowered. The round performs better with the SRP and you could argue that the SRP case is stronger. |
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Get a 16" ARP Scoutt barrel. It will shoot sub moa all day long. You are not going to gain much by going longer.
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