My Brother n law is looking at the 6.8 spc for an AR-15.  He was wondering about either a 16" vs 20" barrel and the differences in effectiveness on deer/hogs and about how far would this cartridge be for deer/hogs?  Any input or real life experiences would be appreciated.  

Thanks,

Bob

Apx 100fps increase with the 20"
300yds would be a safe limit for taking deer or hogs. Look in the hunting forum on 68Forums for stories.

It's a good 300yrd hunting cartridge for either critter from either barrel.

The 6.8 is maximized for the shorter 16" barrell with a gain of only around 100-120fps with the 20". But the 20" should shoot the heavier 130gr bullets better, but that will only apply to handloaders as there is no factory ammo built past 115 GR. I personally have some SSA 110 prohunters and will be using them for Deer/Hog this next hunting season.

130gr Sierra GameKings are really nice out of the 18"-20" rifles.  I think you can get at least 2500fps from a 16" DMR 1:11.25" with that bullet as well...

Deer killed with 20" 6.8 SPC from 240 yards, using Barnes TTSX, loaded over 29.5 grains of RE10X.  This was fired from an AR Performance 20 " 12 twist, 3 groove barrel, which shoots .4 " groups :




Three shots, three dead hogs, again with the "magic bullet"....Barnes TTSX / 29.5 grains RE10X, this time from a Cardinal 16" barrel.  This gun shoots them around 0.7"




One last hog killed with the 12.5" Cardinal SBR, this time with Barnes TSX, 85 grain bullets, factory SSA .



So, you see, whether it is the 12.5, 16 or 20" barrel, as long as you use the right bullets, the 6.8 will maul lots of stuff out to about 300 yards.  Pick whichever barrel seems to feel the best, and most comfortable to you, in the scenarios that you intend to use them.  Velocities are so similar now, with these excellent Barnes bullets, that barrel length is making less and less difference.

I and some friends of mine used our 6.8s for 3 seasons to kill game and the tally as of right now is 38 deer and antelope killed with them.  It's a fact (and not just an opinion) that the 6.8 is good to at least 450 yard on western Mule Deer giving through and through wounds with wound channels about as big around as an egg.  Of the3 38 game animals killed by myself and my friends 5 have been over 400 yards (lazed with range finders) and all but one had an exit wound.  The one that didn't was hit by a friend at the root of the tail and the bullet was found under the skin at the base of its neck.  It was a very large deer.  In fact, that was the largest deer of all the deer killed by us.  A big Montana Mulie.
Remember guys, the cartridge is relatively new, the its basic ballistic recipe is quite old.  It's just a bit better than the original 257 Roberts which is a very good deer round.  It fired a 117 grain bullet at 2620 FPS.   The  6.8 fires a 110 to 115 at 2650 FPS to about 2775 FPS.  So it's going to do just about what your grand dads old 257 has been doing for about 80 years.

16 vs 20 does not really matter so much IMO.
The extra barrel length will get you maybe another 50 yards of real killing power, IE 350 vs 300 yards.

That said I would get a 20" barrel, unless I was trying to build a super light.

The extra 4" did not make much difference in handling to me.

Not mine, but a fellow Arfcom guy.


I have a 16" barrel and love it.

Compromise and go with the 18 :D

I like the 18 for a hunting rig becuase of the balance, and I can walk with it if I want and it still makes a great stand gun.

here is mine:
18 1-11 DMR


I have a 16 inch inbound as well that I will use as a house/tac rifle.

I went with the 16 inch 6.8.  It is pretty much the perfect companion when walking around or when climbing into a stand.