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View Full Version : How short for a 6.8 barrel?


gun toting monkeyboy
09-27-2010, 4:26 PM
Ok, for a pistol or SBR upper, how short can you go with a carbine length gas system? What about with a mid-length gas system? I have been getting the 6.8 bug again, and I already have a nice 18" upper set up. I would like to do an upper that I can use on my pistol lower and still have it function reliably. And still have enough puch to take out for hogs the next time I go to Texas. Let me know what you guys think.

-Mb

wash
09-27-2010, 4:37 PM
The Carbine gas system was used on Commando length uppers which are either 10.5" or 11.5". If you want to go shorter than that you need a pistol length gas system and then lengths as short as 6.5" have been made to work.

As for taking hogs, it depends on range but I think the Commando length would be a safer bet if you're taking any long shots.

gun toting monkeyboy
09-27-2010, 4:42 PM
I would be just fine with an 11.5 inch barrel. I am just wondering if that will work with a mid-length gas system, or if I need to go with the carbine length. I can do either, but the mid-length barrels are easier to get. Either way, I am probably going to just get a 16" barrel from Bison and have AR Barrels cut it down for me.

nrakid88
09-27-2010, 4:59 PM
I have read, i believe on the 6.8 forums, of a member that had an 11 inch barrel with original SPC chamber, and 1/10 twist (if you know 6.8 you know this means comparatively bad velocity) and the thing would still group at 500, however at 600 it was key holing. I know its not the info your looking for, but I think you'll enjoy reading.

nrakid88
09-27-2010, 5:02 PM
Also, you mentioned you want reliability, I really think you should shoot for the carbine length gas system vs. the mid length because with a short barrel you are going to want that extra dwell time (The time gases have to push through the gas tube while the bullet is still going down the barrel) as it should be more conducisve to reliability, by giving a slightly larger margin of error for pressures.

nrakid88
09-28-2010, 11:48 AM
Ask the same question on the 6.8 forums.

Nathan Krynn
09-28-2010, 1:02 PM
We had some 12" 6.8 SPC II 1/11 carbine gas'ed match barrels made and they work well but I have not crono'ed them. I would not suggest mid length though.

wash
09-28-2010, 1:36 PM
Noveske has 10.5" and 12.5" barrels with carbine gas in stock.

Mid-length gas would be too long.

I don't know why you would think that SBR length barrels with mid-length gas would be easier to get.