What advantages are there to a "bull" Barrel

[densa44]

I see varmint calibers offered with a heavy barrel, presumably because it handles the heat better when shot multiple times in quick succession. How much difference does it make? If it is important then why aren't military rifles designed the same way.
What I thought we wanted was cold barrel accuracy.

[Artist]

I'm not too sure about the heat dissipation theory; the bore of the barrel is going to heat up just the same whether the barrel is thick or thin; actually, an argument could be made that a bull barrel will hold heat longer. Furthermore, the temperature of the outside of the barrel is of little (if any) importance, and a bull barrel will definitely take longer to "feel hot" on the outside, but, it's still just a hot on the inside as any barrel would be.

My guess is that a bull barrel would have much less "whip" (harmonics) and therefore would be easier to achieve more consistent accuracy with.

Just my 2 cents.

[rembo]

a bull barrel will always have more balls than a cow barrel....

[jaylow?]

i heavy barrell is way easier to hold on target than a sporter style barrell. basically instead of fighting your shoulder to hold the rifle straight the heavy weight of the barrell does that work for you. try one and see what i mean.

[HunterDave]

Originally Posted by densa44

If it is important then why aren't military rifles designed the same way.

$$$$$

[nanuk-O-dah-Nort]

I think the idea is the thicker barrel whips less upon firing.

and the shorter the better for accuracy as a general rule, cause shorter makes it even stronger.

But every barrel is different and some long ones are accurate.

also, ones that are stress relieved tend to be more accurate.

Also, some very thin ones can be accurate...

hmm... I guess it is hard to generalize....

but Short, Fat tend to be more accurate, all else being equal

the above is purely my opinion and in no way reflects the views of my managment

[densa44]

There is new research that promotes cutting a barrel to make it shorter and thus less "whip" . Form what I read this seems to work. As short as 18". As long as all the powder burns it may work O.K. Any experience out there?
Oh and as far as the heavier barrel helping to hold on target. The gun is heavy enough now especially with a scope. I can hit what I aim at, it is carrying the damn thing that is the problem!

[bwcweld]

Originally Posted by Artist

I'm not too sure about the heat dissipation theory; the bore of the barrel is going to heat up just the same whether the barrel is thick or thin; actually, an argument could be made that a bull barrel will hold heat longer. Furthermore, the temperature of the outside of the barrel is of little (if any) importance, and a bull barrel will definitely take longer to "feel hot" on the outside, but, it's still just a hot on the inside as any barrel would be.

My guess is that a bull barrel would have much less "whip" (harmonics) and therefore would be easier to achieve more consistent accuracy with.

Just my 2 cents.

Not true...
The extra material soaks the heat away from the bore faster. The only time the bore would be much hotter is when theres a bullet going through it. And it wont necessarily hold heat longer and it takes way longer to get heated up. And yes the barrel has less give so its more accurate. Do a rapid fire through a sporter barrel then through a bull barrel and compare bore temperatures and there would be a signifigant difference. Especially with a stainless barrel which will dissipate heat even faster.

[Leeper]

What particular properties enable stainless to dissipate heat faster? Does this capability vary according to the composition of the stainless (more or less nickel in the alloy, for instance). I ask this because I know the bright finish makes heat dissipation less efficient than a dark finish, all else being equal.
A heavy baarel does act as a heat sink and transfers heat away from the bore. Extra weight also dampens vibration.
Cold bore accuracy is paramount in a hunting rifle or in a sniper rifle but, in a field full of gophers, heat can become an real issue. The same is true on the target range in competition. If the course of fire calls for fifteen shots in a certain amount of time, that's what you have to shoot. A barrel which becomes less accurate due to haet buildup, is of little value. Leeper

[Sputnik]

Not my words, but a good description:

Heavy barrels take longer to heat-up, thus maintaining good accuracy for more shots. They are also usually more consistent in the way they vibrate as a bullet passes down their length, which is very important for good accuracy. They resist outside bending forces, like changes in forearm pressure or pressure from a sling pulling the forearm against one side of the barrel, better than light barrels. They are less sensitive to how they are bedded in the stock. Their weight (within reason) makes it easier to hold the rifle steady. For all of these reasons, heavy barrels are generally more accurate than lighter barrels.

[bwcweld]

Originally Posted by Leeper

What particular properties enable stainless to dissipate heat faster? Does this capability vary according to the composition of the stainless (more or less nickel in the alloy, for instance). I ask this because I know the bright finish makes heat dissipation less efficient than a dark finish, all else being equal.
A heavy baarel does act as a heat sink and transfers heat away from the bore. Extra weight also dampens vibration.
Cold bore accuracy is paramount in a hunting rifle or in a sniper rifle but, in a field full of gophers, heat can become an real issue. The same is true on the target range in competition. If the course of fire calls for fifteen shots in a certain amount of time, that's what you have to shoot. A barrel which becomes less accurate due to haet buildup, is of little value. Leeper

I think rifle barrels are high nickel for the reason of heat dissipation and corrosion resistance. The finish is all dependant on how theyre finished. Obviously higher chromium content stainless can be taken to a higher sheen . But now im curious to fin out the different grades of stainless barrels and their compositions.

[Pathfinder76]

http://www.youtube.com/watch?v=TRRahHX9Zkg

[catnthehat]

Originally Posted by chuck

http://www.youtube.com/watch?v=TRRahHX9Zkg

But Chuck, as Big Stick explains, that is a COW barrel, I don't think i would break in a bull barrel that way - you may not be able to throw it as far!!
Cat

[Bushrat]

His breakin routine needs refinement. At 700 yds the hits on the gong are a little left of center. The cause of this is from the rifle being thrown down always on the left side. For the POI to be centered it should be thrown down alternating from side to side equally then it will hit dead center. A one sided break in is an incomplete break in.

[catnthehat]

Originally Posted by Bushrat

His breakin routine needs refinement. At 700 yds the hits on the gong are a little left of center. The cause of this is from the rifle being thrown down always on the left side. For the POI to be centered it should be thrown down alternating from side to side equally then it will hit dead center. A one sided break in is an incomplete break in.

I'll have to remember that, THANKS BR!!
Maybe I can get Dick284 to send me one of his new re-barrels so I can check it out!
Cat

[Traps]

The terms to describe the ability for a barrel to give off heat is heat transfer coefficient and is not a property of the material but a function of all meaningful variables like speed of the fluid around the barrel, temperature of surroundings, surface finish, etc. Its a real bear to describe and usually is one of those properties that has to be found using laboratory conditions. To say one is more than the other is pretty tough to say.

A bull barrel is stiffer. The stiffness of a bar is dependent on the radius to the power of four. A 1 inch barrel is 3.62 times stiffer than a 0.725 inch barrel. Bull barrels as a result have a lower amplitude when the bullet is travelling down the barrel and they tend to be shorter as well, these two things create fewer nodal points which all end up resulting in less barrel vibration. Where the bull barrel shines is it allows greater precision. Take two barrels side by side one a bull, the other a sporter and with the same ammo and standard deviation and you'll find the bull barrel to be more forgiving. At least in theory.

Nickel's purpose in steel is to increase tensile strength and provides uniformity which is desired to handle higher pressures and prevent fatigue failure. Chromium increases hardness which is desired in creating hard rifling.

[Leeper]

Traps,
Thanks for the info. My question was simply to establish whether or not one type of steel would have greater heat transfer properties than another. Specifically, would variations in alloying elements result in a greater or lesser ability to transfer heat. I don't have a clue. I know that aluminum sheds heat faster than iron, for instance, and was curious as to variations within different families of steels.
Ultimately, this will probably remain one of those areas, like so many others, where I will have to confess ignorance! Leeper

[bwcweld]

Well I studied metallurgy in college and yes stainless does transfer heat faster than carbon steel.

[FunwithGuns]

Originally Posted by Traps

Nickel's purpose in steel is to increase tensile strength and provides uniformity which is desired to handle higher pressures and prevent fatigue failure. Chromium increases hardness which is desired in creating hard rifling.

Nickel is a non-factor in barrels as they almost always made from a chromium based stainless with no nickle content. Usually a 410/420 grade is used which can be hardened vs the austenitic grades (304/316 18-8, etc.) which can't be hardened with heat-treatment.

[CaberTosser]

As far as the military question goes; how many troops can you thinkof who would want to carry an extra 3-4lb of rifle in addition to their other gear and ammo? Not an issue for mounted or crew served weapons, but certainly a big factor for the average infantryman.

[catnthehat]

Originally Posted by CaberTosser

As far as the military question goes; how many troops can you thinkof who would want to carry an extra 3-4lb of rifle in addition to their other gear and ammo? Not an issue for mounted or crew served weapons, but certainly a big factor for the average infantryman.

The accuracy parameters are certainly different for general ranks infantry than for dedicated snipers, and even then, as leeper mentioned , a cold bore shot is paramount , and possibly a second shot, but not sustained fire.
Cat

[Traps]

Originally Posted by FunwithGuns

Nickel is a non-factor in barrels as they almost always made from a chromium based stainless with no nickle content. Usually a 410/420 grade is used which can be hardened vs the austenitic grades (304/316 18-8, etc.) which can't be hardened with heat-treatment.

Rifle barrels are usually made from steel alloys called ordnance steel, nickel steel, chrome-molybdenum steel, or stainless steel.

[Traps]

Leeper

Alloys do influence the heat transfer coefficient but I am in the same boat and plead ignorance as to what the different alloys do in this regard.