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Dzscubie 04-07-2010 10:36 PM

Question on AR fluted barrel
Ok, I need your expertise AR gurus out there. What is a fluted barrel for and what is the reason for having one on an AR . I have seen more and more of them popping up but like the boogaloo, it plumb evades me. :confused:

Dillinger 04-07-2010 11:12 PM

JD here, and definitely NOT an expert.

The theory behind the fluted barrel was two fold. 1) Save on front end weight and get the balance back closer to the grip. 2) The cutting of flutes are supposed to help the barrel cool more evenly. Whatever.

Look, a bull barrel is a bull barrel for a reason. You want tack driver accuracy.

Now, when someone buys a heavy barrel weapon and has to hump it places, they want to start cutting weight out of the thing. Blasphemy in my opinion, but what do I know?

So, someone came up with the idea of cutting flutes down the barrel to shave weight, keep the bull barrel profile and "rigidity" ( because the whole barrel is not fluted ) so you have the best of both worlds.

Now, I am not a small guy. If I spec a rifle, I spec a rifle weight and I expect to have to carry it. I can't see myself EVER getting a bull barrel and then fluting the hell out of it to get weight down.

But that is me. A lot of people request it. It's very popular in both the Hunting World and the AR Varminting world. If you have a mill, you can set up the barrel vice and do 5 or 6 or 7 in just a day or two depending on the number and depth of the flutes and make a nice profit for the week.

It's all preference my friend. Everyone likes what they like.


Dzscubie 04-07-2010 11:20 PM

Thanks JD I knew I could count on you.

I was asked this by one of my officer and I was ashamed to say I really did not know what the flutes were for. We did discus the quicker cooling idea but did not know that it was a bull barrel with the flutes cut in it.

I donít feel I would want one but, as you say, different people like different stuff.

Thanks again

Dillinger 04-07-2010 11:25 PM

Scubie - A barrel does not have to have a "bull" profile to be fluted, it's just the most common.

The depth of the flutes is determined by the thickness of the barrel wall.

If you have a thin, or tapering, barrel profile then the flutes can be very shallow or they can taper along with the profile to match.

The end result is usually a reduction in weight. Rarely do we have someone comes in that wants shallow flutes cut for "style" purposes. :cool:

Car54 04-07-2010 11:42 PM

JD, do you know if fluting has any effect on accuracy or bullet spin?

Dillinger 04-08-2010 12:01 AM


Originally Posted by Car54 (Post 266275)
JD, do you know if fluting has any effect on accuracy or bullet spin?

That is subjective Car. Very, very subjective depending on which side of the fence you stake your tent.

One of the big things that affects accuracy is harmonics induced on the barrel by the explosion of the round being touched off and the gas pressure being released, especially from one round to another.

Now, take a magnum caliber like a .300 Win mag. Massive round, traveling at incrediable speeds and ground zero to a small explosion when you touch it off.

Take that round and put it along side a .22LR

Which one is going to induce more pressure on the shooter through recoil? Which one is going to generate more force on the action?

Obviously the .300 Win mag is going to do everything with more aggression.

So, put them both in an identical metal cylinder and ask that cylinder to take that force and convert it to torque to spin the bullet. Then take that cylinder and rest it on top of something like a car tire that rotates on an axle. Round and Round.

If the walls of the cylinder are paper thin, and it weighs only a few ounces, what will happen? You touch that round off and the .22LR is going to give the thin cylinder a little spin and the .300 Win is going to spin it like a top.

If the walls of that cylinder are as thick as battleship armor and it weighs dozens or hundreds of pounds, what will happen? The .22LR probably isn't going to cause the wheel to move at all, and the .300 Win Mag is going to cause VERY little movement.

That is basically what happens when you touch off your round. You induce MASSIVE torque into the barrel via the lands and grooves to get the bullet spinning on it's axis to cause rifling.

Have you ever taken a drill and put a large caliber drill bit through a piece of metal and have it BITE?? What happens to your wrist??

Just food for thought.....


NY Marksman 04-08-2010 12:03 AM

Fluting will not have anything to do with accuracy but as said before it will aid in cooling and weight reduction. I have an 18 inch Stainless Steel fluted Sabre Defense barrel and it is extremely accurate.

Dillinger 04-08-2010 12:05 AM


Originally Posted by NY Marksman (Post 266298)
Fluting will not have anything to do with accuracy

While you may personally believe that, I would challenge that statement on any shooting range in the world with rifles produced to the exact same specs, having the only difference be a true bull barrel versus a fluted barrel.

But that is my personal belief based on experience that I have personally seen.


Car54 04-08-2010 12:22 AM

1 Attachment(s)
Boy do I feel stupid. I was assuming that the fluting was inside the barrel in addition to the rifling.

ThorsHammer 04-08-2010 12:28 AM

I figured it wouldn't make a smack of a different since I am not rifleman enough to out shoot either type of barrel. Makes sense on the bull barrel though, the added weight adds to controllability of the rifle.

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