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Durkin Tactical Franklin Armory
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Posted: 10/13/2012 6:19:18 AM EDT
Link Posted: 10/15/2012 6:17:55 PM EDT
KevinB(KAC) says a 16" can do anything a 20". I have a  7.62mm 16" MATEN build and I'am happy with the results that I get.
Link Posted: 10/15/2012 7:13:45 PM EDT
I respect KevinB.

BUTT!!!  when it comes to .308 in an AR platform:

1)  16" cannot do a 20"

2)  20" cannot do a 24"

Modern powders say so.

EDIT:  Electronics and targets back that up.

Show me a 16" that can break 2600fps with Varget...
and that speed wins F-Class in bolt guns.

just da-da-damn

Link Posted: 10/15/2012 7:25:47 PM EDT
Article I found when Googling this subject.........Barrel Length and the Precision Rifle
Link Posted: 10/16/2012 12:50:25 PM EDT
Wow, the replies here are rich with data!  
Link Posted: 10/16/2012 1:14:54 PM EDT
Link Posted: 10/16/2012 3:05:42 PM EDT
I've jacked this from elsewhere on the same topic. take it for what it's worth.  

150 gr HPBT Win 748 loaded to a chamber pressure of 56.4K PSI WARM load 45 gr NOT a starting load. I chose 748 as the powder as it is most like NATO powder.

26" = 2918 FPS MP= 6.6K PSI ––99.6 % powder burnt -2836 ft/lbs
24" = 2873 FPS MP= 7.4K PSI ––––––––––––––––––––––––––––2750 ft/lbs
22" = 2823 FPS MP= 8.2K PSI ––––––––––––––––––––––––––––2655 ft/lbs
20" = 2766 FPS MP= 9.2K PSI ––98.7 % powder burnt -2548 ft/lbs
18" = 2700 FPS MP= 10.5K PSI ––––––––––––––––––––––––––––2428 ft/lbs
16" = 2623 FPS MP= 12.0K PSI -97% powder burnt ––––2291 ft/lbs
14" = 2531 FPS MP= 14.0K PSI ––––––––––––––––––––––––––2133 ft/lbs
12" = 2417 FPS MP= 16.7K PSI -94% powder burnt ––1946 ft/lbs
10" = 2273 FPS MP= 20.5K PSI ––––––––––––––––––––––––––1721 ft/lbs
8.0"= 2080 FPS MP= 26.0K PSI -87% powder burnt. -1441 ft/lbs
6.0"= 1800 FPS MP= 34.1K PSI -79.4% powder burnt -1080 ft lbs
Link Posted: 10/16/2012 4:18:32 PM EDT
Link Posted: 10/17/2012 3:25:25 PM EDT
Link Posted: 10/17/2012 4:16:07 PM EDT
What are you planning on doing with it?  Hunting, match, precision?  Makes a difference.  If its for a hunting, then the 16" is plenty.  I've done well with mine.  Otherwise, I think the 20" would be my goto length.
Link Posted: 10/17/2012 4:34:59 PM EDT
Link Posted: 10/18/2012 4:56:00 AM EDT
I think gains, or losses, with factory loaded heavier bullets would be less.

IIRC, gains above 18 inches were marginal as per some snipers testing the same gun and chopping back the barrel 2 inches per each chrono event.

Obviously, a hot loaded handload with a light bullet might need more tube.  YMMV,and sorry don't have link...
Link Posted: 10/19/2012 4:28:14 AM EDT
Great table and information!!!
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