AR Sponsor
Posted: 6/12/2009 9:44:33 AM EDT
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i am currently looking at a used upper. the current owner had the barrel fluted to cut down on weight by a local smith. as an engineer, this doesn't sound like a great idea to me...the factory engineered the wall thickness to a certain spec. it seems like removing material is weakening the barrel and cutting into its stress capacity.
so the question....what do i need to look for? are there any guidelines on how deep/wide/ofen the flutes should occur? is there a resource i can research? thanks, -matt |
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as long the flutes were done professionally it shouldn't matter, just don't buy a bbl that's had the dremel tool taken to it. there's a pretty funny picture of that floating around here somewhere. i can't seem to find it
eta: here's a pic of a professionally fluted ar15 bbl: 
in addition to the weight reduction, bbl fluting supposedly improves bbl harmonics which will increase accuracy and repeatability |
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Barrel fluting does a couple of things. Contrary to popular belief, it DOES NOT increase a barrel's accuracy. This is the way to think of it:
1. A non-fluted barrel is much stiffer (and thus, more accurate) than a fluted barrel of the same outside diameter. However, the fluted barrel will dissipate heat faster and be lighter. 2. A fluted barrel, however, is stiffer than a non-fluted barrel of the same weight. Take any given barrel, flute it, and it will lose a bit of accuracy but gain in heat dissipation and weigh less. |
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Quoted:
Barrel fluting does a couple of things. Contrary to popular belief, it DOES NOT increase a barrel's accuracy. This is the way to think of it: 1. A non-fluted barrel is much stiffer (and thus, more accurate) than a fluted barrel of the same outside diameter. However, the fluted barrel will dissipate heat faster and be lighter. 2. A fluted barrel, however, is stiffer than a non-fluted barrel of the same weight. Take any given barrel, flute it, and it will lose a bit of accuracy but gain in heat dissipation and weigh less. fluting INCREASES a bbl's stiffness, thus improving harmonics and repeatability. |
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Quoted:
Quoted:
Barrel fluting does a couple of things. Contrary to popular belief, it DOES NOT increase a barrel's accuracy. This is the way to think of it: 1. A non-fluted barrel is much stiffer (and thus, more accurate) than a fluted barrel of the same outside diameter. However, the fluted barrel will dissipate heat faster and be lighter. 2. A fluted barrel, however, is stiffer than a non-fluted barrel of the same weight. Take any given barrel, flute it, and it will lose a bit of accuracy but gain in heat dissipation and weigh less. fluting INCREASES a bbl's stiffness, thus improving harmonics and repeatability. Ehh, no. It doesn't. Anytime you take a barrel and flute it, the end result will be a slightly less stiff barrel, but one that dissipates heat faster and weighs less. |
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james is right on the sectional properties thing. when you're cutting the flutes, you're removing material. this decreases the moment of inertia of the shape, which is used in the calculation of stiffness/deflection. for two identical barrels (save one is fluted) the un-molested barrel will deflect less under the same applied loads. the fluted barrel will shed heat faster, since you're increasing the surface area with the flutes, and heat transfer is a direct function of area.
i can't speak to the harmonics issues. thanks for the help guys. keep them coming. -matt |
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Quoted:
Quoted:
Quoted:
Barrel fluting does a couple of things. Contrary to popular belief, it DOES NOT increase a barrel's accuracy. This is the way to think of it: 1. A non-fluted barrel is much stiffer (and thus, more accurate) than a fluted barrel of the same outside diameter. However, the fluted barrel will dissipate heat faster and be lighter. 2. A fluted barrel, however, is stiffer than a non-fluted barrel of the same weight. Take any given barrel, flute it, and it will lose a bit of accuracy but gain in heat dissipation and weigh less. fluting INCREASES a bbl's stiffness, thus improving harmonics and repeatability. Ehh, no. It doesn't. Anytime you take a barrel and flute it, the end result will be a slightly less stiff barrel, but one that dissipates heat faster and weighs less. perhaps i'm incorrect, but similar modifications are made to sheet metal to increase it's stiffness (corrugation is the process) eta: now that i think about it, corrugation doesn't really remove any material like fluting. i stand corrected 
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