The "best" barrel length for AR

9ineMM

9ineMM

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After doing considerable research on the subject, I have still not not come to a conclusive answer. Many of you reading may ask "best length for what purpose?" A valid question of course. I am looking for not only objective points but subjective views. I have read all sorts of ballistic reports etc etc.

I guess a more accurate question is: "If you were to have only one AR15 for a multitude of purposes such as CQB to urban environments to extended environments and threats at 100+ yards, what barrel length would you choose?"
 
The expression "How long is a piece of string?" comes to mind.

The world's armies seem to go with something around 16 inches. So my vote by default would have to go with that. Seems they check off all the boxes on your list for usage.
 
I totally understand the "it depends" answers, hence why i am looking for more a consensus with some "real world" applications. I look forward to more opinions :) (and thanks to all that have already replied)
 
Barrel length totally depends on purpose. If you are competing in 3 gun, IPSC or other shoot and move type games, then 14.5" and 16" seems the most suitable, however, if you want to compete in service rifle with iron sights, 20" heavy barrel giving you the longer sight radius is the best choice. As hunting is not allowed with the "Modern Sporting Rifle" here in Canada, ballistics and performance, other than accuracy doesn't really matter.

Scott
 
I believe I seen a video saying the 14.5" was a result of shorter being too extreme for hearing damage without protection.

That being said it is a nice middle ground. If I could only have one, probably 14.5".

The previous post saying 10.5" is long enough to not have much flash is a bit strange to me. My 10.5" is a flame thrower.
 
Didn't the PPCLI switch over to the 14.5" barrel C8 from the standard C7 20" length? (or at least a battalion of the regiment)

According to guys like Larry Vickers and Kyle Lamb, the 14.5" is probably the best with current issue ammo for a general-purpose service rifle. Easy enough to get in and out of vehicles and buildings (compared to a 20" barrel rifle), with enough velocity and accuracy to get consistent hits out to about 400m.

Those guys should know what they're talking about.
 
16" with mid-length gas. If it only comes in carbine length gas like colt canada then 14.5" will work (why the hold up for a CC 14.5" MRR?)
 
The military uses 1/7 to stabilize the long tracer rounds. 1/8 would be the ideal twist for the widest variety of ammo.

There may be issues with the heavy stuff like 77grn and up but for most people 1/9 will be fine. That's why the commercial market chose 1/9, because it worked with everything in common use at the time. In fact, you may have issues using 55gn in 1/7 but there are plenty of people who use it without issue as well.

All of my barrels are 1/7, mainly because that's what most offer in the "mil spec" craze. If it was more common 1/8 .223 Wylde on 16" lightweight profile midlength would be my preference for an all purpose fighting rifle. You only lose 150 fps compared to a 20". Colt Canada did a lot of ballistic testing to arrive at 15.7".
 
I have to disagree here. The military uses 1 in 7 twist to stabilize bullets in cold weather. This is an assumption on my part, but you will probably get crap accuracy with 62gr ball out of a 16" barrel in very cold weather even with a 1 in 7 twist barrel. Also according to Bryan Litz the 77gr SMK daddy will stabilize better in a 1 in 9 than the 62gr LC FMJBT.

My experience with 68gr Hornady HPBT Match supports this. Great accuracy out of a 24" 1 in 9 bolt gun in the summer, -20c, total crap, even adjusting the powder for the cold. The 68gr Hdy and the LC 62gr have almost identical stability factors.
 
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