Bull Barrel Advantages
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osborne - sounds like you've taken a basic course in heat transfer...
The controlling resistance is the free/forced convection film coefficent on the outside surface - about the same for a sporter weight and a heavy weight barrel (no flutes)
No need to do a detailed finite element analysis. As barrel dia increases, barrel mass increases with radius squared, whereas surface area increases linearly. The net result is less surface, and heat transfer, area per unit of mass for a HB.
Assuming the two barrels are at the same temp, the lighter one would cool quicker. However, as most HB rifles have free floated barrels with generous channel clearance, they may enjoy better heat dissipation than their sporter weight counterparts...
The controlling resistance is the free/forced convection film coefficent on the outside surface - about the same for a sporter weight and a heavy weight barrel (no flutes)
No need to do a detailed finite element analysis. As barrel dia increases, barrel mass increases with radius squared, whereas surface area increases linearly. The net result is less surface, and heat transfer, area per unit of mass for a HB.
Assuming the two barrels are at the same temp, the lighter one would cool quicker. However, as most HB rifles have free floated barrels with generous channel clearance, they may enjoy better heat dissipation than their sporter weight counterparts...
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BIGREDD said:I have news for you Ted... that is not a theory... that is science, and it is a fact. Your idea is the speculative one...Bench rest and competetive shooters know this and so does the military... the larger the surface area the quicker the barrel cools.
Bigredd, your understanding of the science is not borne out by what really happens.
Get two barrels hot and see which one cools the quickest. I have actually done it with a HB and a sporter 223, and the smaller diameter barrel cools considerably quicker. Try it and see.
Again, you've got plenty of guns at the shop. Take a couple to the range and give it a try!
Ted
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cosmic said:
Precisely...... the mass is directly proportional to the radius squared, while the surface is directly proportional to the diameter.
If you double the diameter of a barrel you quadruple the mass, but the surface area only doubles. Triple it and the mass increases by a factor of nine times, while the surface area goes up by a factor of three.
Redd is trying to eat cake, when he should be trying the pi.
Ted
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whoa, hold up there. A bigger barrel has a higher rate of energy dissipation, based on surface. You're all assuming that this is a closed system, when it's not. Energy (heat) is constantly being added as rounds are fired. So, all else equal, you will be able to add energy to the system at a higher rate than in the case of a sporter. In otherwords, the net amount of rounds fired over time would be higher for the heavy barrel. This is not (quite) the same as saying that a heavy barrel cools faster, though, because it doesnt. Between a heavy barrel and a sporter both at the same temperature, the lighter one WILL attain equilibium much sooner.
To illustrate: assume for a sec that an HB has an over heat dissipation ability of 100W when at say 40*. A sporter barrel we'll assume can do 50W. Let's also assume that each shot adds 100J of energy. After the first few shots bring the barrel temp up to 40* (because dissipation may vary based on barrel temperature delta vs ambient), the heavy barrel will attain equilibrium at 1 shot per second (+100J at the shot, and the barrel can dissipate 100J/s (W)). The Sporter can sustain 1 shot every two seconds (+100J, and -50J/s*2s)
To illustrate: assume for a sec that an HB has an over heat dissipation ability of 100W when at say 40*. A sporter barrel we'll assume can do 50W. Let's also assume that each shot adds 100J of energy. After the first few shots bring the barrel temp up to 40* (because dissipation may vary based on barrel temperature delta vs ambient), the heavy barrel will attain equilibrium at 1 shot per second (+100J at the shot, and the barrel can dissipate 100J/s (W)). The Sporter can sustain 1 shot every two seconds (+100J, and -50J/s*2s)
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I'm surprised that nobody mentioned that fact that another reason to use a heavy barrel is for greater stifness which translates into greater accuracy potential, and you don't need a super long tube either! Shorter heavy bbl rifles, are often more accurate, simply because they are stiffer! i.e., Remington 700LTR. In most cases minimal reductions in MV aren't of any consequence in real world applications.
As for the issue of barrel heat-up, I haven't really noticed any appreciable decline in accuracy under field conditions. From the bench you'll see vertical stringing, but nothing that really concerns me. Then again, I'm not shooting hundreds of rounds in an afternoon in the middle of a praire dog town either! Coyote hunting, you don't often fire more than a couple of rounds...if you do, you aren't hitting anything anyway!
I would suspect that a heavy fluted bull/varmint profile barrel (that has been cryogenically relieved of stress of course!) should heat up slower than a sporter weight barrel, while cooling at a comparable rate, due to increased surface are AND greater air flow over said surface area. Most varmint rifles with bull barrels are free floated with generous barrel channels that should permit greater air flow over the barrel surface compared to the average sporter rifle with pencil barrel and extremely tight barrel channels.
I'm no metallurgist or expert in thermodynamics, but I have observed the above under real field conditions. I like both, but tend to prefer heavy barrel rifles, whether it is my 700VS in .22-250 for coyotes or 700VS in .308Win or 700 Sendero in 7mm Rem Mag I use on Moose or Caribou. However, I don't feel I'm at a disadvantage toting my 700BDL in 7mm Rem Mag or 700 Classic in .223Rem.
As for the issue of barrel heat-up, I haven't really noticed any appreciable decline in accuracy under field conditions. From the bench you'll see vertical stringing, but nothing that really concerns me. Then again, I'm not shooting hundreds of rounds in an afternoon in the middle of a praire dog town either! Coyote hunting, you don't often fire more than a couple of rounds...if you do, you aren't hitting anything anyway!
I would suspect that a heavy fluted bull/varmint profile barrel (that has been cryogenically relieved of stress of course!) should heat up slower than a sporter weight barrel, while cooling at a comparable rate, due to increased surface are AND greater air flow over said surface area. Most varmint rifles with bull barrels are free floated with generous barrel channels that should permit greater air flow over the barrel surface compared to the average sporter rifle with pencil barrel and extremely tight barrel channels.
I'm no metallurgist or expert in thermodynamics, but I have observed the above under real field conditions. I like both, but tend to prefer heavy barrel rifles, whether it is my 700VS in .22-250 for coyotes or 700VS in .308Win or 700 Sendero in 7mm Rem Mag I use on Moose or Caribou. However, I don't feel I'm at a disadvantage toting my 700BDL in 7mm Rem Mag or 700 Classic in .223Rem.
X-man said:
That's apples to oranges. The only way to compare HB cooling VS sporter is to make all the rest equal - if you flute the HB, then compare to a fluted sporter. If you have generous channels for the HB, then you have to compare it to a similarly configured sporter setup, or you're not comparing the barrels's effectiveness, but the other 'features'
Firstly Ted I have heavy barrels and I have medium heavy barrels and I have sporter wieght barrels... and I shoot them.
I believe in first hand experience and what I have found is that my Heavy barrels cool faster than my sporter-weights. Not scientific by any stretch.
I have read that the military uses heavy barrels for specific uses for this very reason on both their machine guns and their AR type rifles.
I have also read various barrel reports from manufactuters that this is the case.
I have been told by some very knowledgable competitive shooters and firearms experts that this is the case.
I would like to see some science that proves it otherwise.... until then you guys are just offering an opinion... like mine.
I believe in first hand experience and what I have found is that my Heavy barrels cool faster than my sporter-weights. Not scientific by any stretch.
I have read that the military uses heavy barrels for specific uses for this very reason on both their machine guns and their AR type rifles.
I have also read various barrel reports from manufactuters that this is the case.
I have been told by some very knowledgable competitive shooters and firearms experts that this is the case.
I would like to see some science that proves it otherwise.... until then you guys are just offering an opinion... like mine.
BIGREDD said:
BIGREDD, we both are entitled to those opinions, and I respect yours. The science has already been explained, and as posted by prosper is just basic thermodynamics.
I just realized, my friend, that we may be talking about two different things here. I am not talking about cooling between shots and how that might affect accuracy. I am talking about a barrel cooling down to ambient temoerature after the shooting is finished.
In other words what I am saying is that it will take longer for the HB to get "cold" than it will the sporter weight.
Ted
Yeah well maybe your right Ted... but no matter what Super Cub is gotta be wrong!
I still need to see the science, I am sure someone will find the relative research. I can't seem to find anything but conjecture and opinion.
I still need to see the science, I am sure someone will find the relative research. I can't seem to find anything but conjecture and opinion.
Gents - This stuff isnt exactly cutting edge R+D. Any third year mechanical engineering student would likely encounter such as question on their heat transfer exam.
Bigredd - To clarify my original post - if both the heavy barrel and light barrel enjoy the same cooling regime ( angle, channel clearance, barrel/ambient temp, surfacecoating, etc.) then the light barrel will cool more quickly than the heavy. (Assuming no shots are being fired, see Prospers analysis.)
However, if the sporter rifle has a tight fitting stock, convection heat transfer to air can be compromised. There exists the potential to transfer heat via conduction to the stock if the contact is very precise, such as a bedded surface, otherwise contact resistance (small air gap) limits heat transfer.
Hope this clarifies things - having made a living in the field of heat transfer, its easy to understate matters.
Bigredd - To clarify my original post - if both the heavy barrel and light barrel enjoy the same cooling regime ( angle, channel clearance, barrel/ambient temp, surfacecoating, etc.) then the light barrel will cool more quickly than the heavy. (Assuming no shots are being fired, see Prospers analysis.)
However, if the sporter rifle has a tight fitting stock, convection heat transfer to air can be compromised. There exists the potential to transfer heat via conduction to the stock if the contact is very precise, such as a bedded surface, otherwise contact resistance (small air gap) limits heat transfer.
Hope this clarifies things - having made a living in the field of heat transfer, its easy to understate matters.
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The cooling regime cannot be shared... different mass, different surface areas... you are making it sound simple but it is not that simple. My point is that a larger surface area will dissipate heat at a faster rate than a smaller surface area. This is the same principal that allows fluted barrels to cool faster due to an increased surface area.
Holy crap... I just hit 7900 posts with that bit of bafflegarb!!!
Holy crap... I just hit 7900 posts with that bit of bafflegarb!!!
Heavy Barrels...
I'd like to go on record as stating I have a few heavy barrel rifles I'm fond of... off the bench that is. For packin' / huntin' gimme a rifle with a sporter weight or featherweight barrel any day of the week. Each have their purpose...
I'd like to go on record as stating I have a few heavy barrel rifles I'm fond of... off the bench that is. For packin' / huntin' gimme a rifle with a sporter weight or featherweight barrel any day of the week. Each have their purpose...
Bigredd, cosmic's argument is sound, and Ted's first hand experiences are accurate. For those not familiar with physics, I ofter find it easier to show an example using numbers, and then show the logic behind the numbers.
Take for example a 1" diameter heavy barrel with a .224" bore and a 0.5" sporter barrel with the same bore. The volume of steel in the heavy barrel will be apprximately 0.75 cubic inches per inch of barrel length, whilst the sporter barrel is only 0.16" cubic inches per inch of barrel length. Appoximately 5 times more volume per inch of barrel length for the heavy barrel. (a "NON-linear" relation, volume increases with the radius of the barrel squared).
Now, the surface area of the heavy barrel is 3.14 square inches per 1 inch of barrel length whilst the surface area of the sporter barrel is 1.57. Exactly twice the surface area (a "linear" relation).
sporter barrel= 10 sq inches/CI volume
heavy barrel = 4.2 sq inches/CI volume
As you can see the sporter barrel clearly has more surface area per unit volume of barrel steel. Assuming that the heat transfer is identical per unit surface area between the two barrels (which it is not, but certainly for simplicities sake this is not an unreasonable assumption), then the sporter barrel would cool faster. Assuming heat dissipation is identical per unit surface area disregards any stock irregularities and neglects some more complicated thermal conduction properties within the steel itself, but again this is a reasonable approximation.
Hope this helps the confusion
Take for example a 1" diameter heavy barrel with a .224" bore and a 0.5" sporter barrel with the same bore. The volume of steel in the heavy barrel will be apprximately 0.75 cubic inches per inch of barrel length, whilst the sporter barrel is only 0.16" cubic inches per inch of barrel length. Appoximately 5 times more volume per inch of barrel length for the heavy barrel. (a "NON-linear" relation, volume increases with the radius of the barrel squared).
Now, the surface area of the heavy barrel is 3.14 square inches per 1 inch of barrel length whilst the surface area of the sporter barrel is 1.57. Exactly twice the surface area (a "linear" relation).
sporter barrel= 10 sq inches/CI volume
heavy barrel = 4.2 sq inches/CI volume
As you can see the sporter barrel clearly has more surface area per unit volume of barrel steel. Assuming that the heat transfer is identical per unit surface area between the two barrels (which it is not, but certainly for simplicities sake this is not an unreasonable assumption), then the sporter barrel would cool faster. Assuming heat dissipation is identical per unit surface area disregards any stock irregularities and neglects some more complicated thermal conduction properties within the steel itself, but again this is a reasonable approximation.
Hope this helps the confusion
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Oh, and in regards to fluted barrels, the reason they cool so quickly is the flutes DRASTICALLY increase the surface area, whilest also reducing the volume of the barrel steel. Quite frankly I'm a little tired to get into a dimensional analysis of a fluted barrel's surface area per unit volume, perhaps I will attempt it tommorow. Can someone describe their fluted barrel (ie number of flutes and flute radii of curvature), and I could do this.
