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Old March 6, 2014, 08:31 PM   #1
Dc777
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What is the purpose of a bull barrel?

I have a marlin 917v .17hmr with bull barrel that I am considering trading for a marlin .22 mag. The .22 mag is identical to my gun and I think they use the sane magazines but it isn't a bull barrel. I've never even wondered what the purpose of the bull barrel is but now I'm curious. What are the benefits of a bull barrel?
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Old March 6, 2014, 08:46 PM   #2
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Stability on a rest ( less recoil,less time back on target ). Ability to shoot more rounds in less time with out barrel heat up. Don't fall for the more accurate- It is a wife's tale.
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Old March 6, 2014, 09:40 PM   #3
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When you're discussing a rimfire, the "bull barrel" is mostly a marketing ploy. While the extra weight may steady the hold, the rimfires don't generate enough heat to be a problem.
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Old March 7, 2014, 10:30 AM   #4
Bart B.
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Heavy barrels move less while the bullet goes down it so its bore axis will point closer to where it needs to be for the bullet to hit the aiming point.

They are no more accurate than light weight ones. .22 rimfire free pistols with 8 to 12 inch skinny barrels will shoot just as accurate at 50 meters as a 26 inch heavy thick rifle barrel.

No properly made barrel fit the correct way to the receiver and that barreled action's fit properly to the stock will change point of impact as it heats up. That's what a fraction of a percent of rifle shooters observe shooting good scores in competition.
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Old March 7, 2014, 11:17 AM   #5
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Yep, that's why all the benchrest shooters use pencil barreled rifles.
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Old March 7, 2014, 12:29 PM   #6
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Don't fall for the more accurate- It is a wife's tale.
Technically true. And for most people heavy barrels aren't really necessary. But the added weight, at least to a point will make them easier to shoot more accurately.

For a hunter balance is more important. A hunting rifle needs to have some weight forward to help steady things. That can be accomplished with some pretty light barrels. If the weight is too much in the buttstock the barrel will feel whippy and hard to keep on target. Even though the gun may be heavier.

For the guy wanting to squeeze the last tiny bit of accuracy out of a gun, a heavier barrel will usually do better. Not because of the barrel, because it is easier for the shooter to shoot it well.
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Old March 7, 2014, 01:08 PM   #7
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I was always led to believe that the purpose of a heavy barrel was to dampen the harmonics, a rifle barrel will 'vibrate " with each shot, { think of a tuning fork } and does it differently with each different bullet weight and powder charge. The more you can dampen that vibration the more accurate the rifle, heat dissipation is just a secondary benefit. For the hunter, a bull barrel is usually not necessary nor needed because of the extra weight.
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Old March 7, 2014, 01:37 PM   #8
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Tuning forks and rifle barrels vibrate at their own fixed resonant frequency each time they're shocked to do it. Doesn't matter how much the shock force is. Their dimensions and metallic properties don't change with different amounts of shock.

How much they vibrate or wiggle is constant for a given amount of shock force and direction on them as long as no external restrictions interfere.
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Old March 7, 2014, 01:45 PM   #9
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Bart B. is correct.

Heavier barrels are more massive, so they will have less horizontal movment due to the resonant frequency having to move more mass than an equal length thinner barrel. In essence, they are stiffer.

Stiffer does not necessarily mean more accurate, but it doesn't hurt.

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Old March 7, 2014, 01:50 PM   #10
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Bull barrels tend to be stiffer, heavier, and better at managing heat and recoil.
Stiffer and heavier because it's thicker. It will also heat up slower as well as cool down slower, due to the amount of material being heated.
As someone else mentioned bull barrels aren't as crucial on .22LR's because the cartridge doesn't generate much recoil, so less 'barrel whip' will take place and the weight of the barrel doesn't make much difference in recoil reduction because barely any recoil is being generated by a .22LR.
22's don't generate that much heat either. The same holds true for the other rim fire cases.
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Old March 7, 2014, 02:12 PM   #11
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I've never had a problem with thick or thin barrels changing point of bullet impact going from ambient temperature to very hot for 20 to 30 shots fired in half as many minutes. Same for 10 shots in 1 minute, wait 5 minutes then do it again starting with a hot barrel making it hotter. Nor with thin barrels shooting 24 shots in 50 seconds.

Same for hundreds of others.
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Old March 7, 2014, 02:50 PM   #12
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If everything is machine true, there should be very minimal shifting (not significant enough to detect).

However if things are not true, then here are some of the common causes of shifting as the rifle heats up.

An off center bore can cause shifting, as the thin side and thick side heat differently and expand at different rates.

An improperly mated action shoulder to barrel interface can also cause shifting as the rifle heats up, torquing the barrel to one side as metal expands.

Improper bedding can cause shifting, usually vertical, as the rifle heats up.

There are probably a few more, but those were the ones I could think of off the top of my head.

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Old March 7, 2014, 05:22 PM   #13
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When I used the term " like a tuning fork" , I used that for example, that the rifle barrel will vibrate. Like a tuning form will vibrate when struck, so will a rifle barrel vibrate when shot. I wanted to use terms that the every day new shooter would understand.
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Old March 7, 2014, 05:50 PM   #14
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RJay, your tuning fork is a good example. Rifle barrels vibrate mostly in the vertical plane with tratitional stock shapes. Their recoil force axis is typically above their contact point on humans that absorbs most of the recoil.

The mechanical engineer who wrote software for me to calculate barrel stiffness used two environments; one with both ends of the barrel free and the other with the breech end fixed. 'Twas interesting to see a barrel free at both ends vibrates at a higher resonant frequency than one fixed at its breech end.

Hodaka, a barrel's whip frequency and amount is the same for every shot of the same load. All bullets leave about a tiny range in its whip cycle. With the right recipie, they'll all leave at the same place. Doesn't matter if a skinny barrel whips more than a thick one. Repeatability is the basis for best accuracy.
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Old March 7, 2014, 06:46 PM   #15
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Bart, I understand your point about barrel whip and consistency. However, I believe that the greater mass of a heavy barrel will have less variability in the amount of whip from shot to shot. My personal experience has been that heavy barrels are indeed more accurate than lighter ones, all things considered. Granted, a light Hart barrel will outshoot most of the major manufacturers varmit barrels but with equal quality barrels the heavier ones are more consistent, hence my comment regarding the benchrest guns. Not worth a damn for hunting though.
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Old March 7, 2014, 08:37 PM   #16
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hodaka- If you were to take a Heavy good quality barrel and it's equal in skinny. Put them in the same hands. There would be no difference in accuracy. The accuracy issue only shows up in rapid fire ( barrel warm up). The diameter of the barrel has no affect on accuracy. The side affects of a heavy barrel do, but the barrel does not.

I think you are meaning because it is heavier, It recoils less, easier to hold steady on target after shot,and is more steady. Those are side affects of a heavy barrel, it has nothing to do with the barrel being a bigger diameter.
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Old March 7, 2014, 08:49 PM   #17
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hodaka, the most accurate 26 and 30 caliber long range benchrest rifle barrels are often 1.4 to 1.5 inch thick and 28+ inches long weighing 15 to 20 pounds. They shoot all their shots into about 6 inches at 1000 yards in good conditions. Once in a while, they'll put five of them into 2 inches or less, most groups are in the 3 to 5 inch range and a few are in the 6 inch range. These rifles weigh 30 pounds or more.

An equal length 6-pound barrel 1.2 inch at the breech quickly tapering to .7 inch at its muzzle and weighing 5 to 6 pounds is one heck of a lot whippier and less stiff than the one above. But when shot in the same conditions, it'll equal that benchrest guns accuracy. This .308 Win rifle is normally shot slung up in prone weighs about 13 pounds and this is the accuracy attained with the best of them when tested for it, but not in competition when it's hand held.

They're equal in the accuracy department.

I agree that a stiffer barrel may have a lower amplitude of its wiggle at a given frequency, but with decent muzzle velocity spread, the time it takes for the bullet to leave the barrel still makes it leave at the same small area in its whip cycle. And sometimes, bullets with a greater spread in muzzle velocity shot from more whippy barrels have that compensated and they all arrive at the same place on target. Faster ones leave sooner than slower ones on the muzzle axis up swing. The Brits proved this happens with their SMLE .303's over a hundred years ago.
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Old March 7, 2014, 10:15 PM   #18
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There's no denying that Bart knows what he's talking about, but (and whip me with a dead dog for being a non-believer) it was and is my opinion that a bull barrel can get you better accuracy. Folks can wave pages of theory at me and spout advanced mathematics, but in the real world if I had to put holes in paper as accurately as possible at any distance, and weight was not a consideration, the barrel will NOT be pencil thin. It'll be a fat barrel. I may be wrong in my beliefs, but I am comfortable in those beliefs.
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Old March 7, 2014, 10:37 PM   #19
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I agree that a stiffer barrel may have a lower amplitude of its wiggle at a given frequency, but with decent muzzle velocity spread, the time it takes for the bullet to leave the barrel still makes it leave at the same small area in its whip cycle. And sometimes, bullets with a greater spread in muzzle velocity shot from more whippy barrels have that compensated and they all arrive at the same place on target. Faster ones leave sooner than slower ones on the muzzle axis up swing. The Brits proved this happens with their SMLE .303's over a hundred years ago.
Yes, but accuracy at some of the mid ranges was complete crap too :P

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Old March 7, 2014, 10:55 PM   #20
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Ability to shoot more rounds in less time with out barrel heat up. Don't fall for the more accurate- It is a wife's tale.
Why would it matter whether the barrel heats up if the more accurate (while hot) is a wife's tale?
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Old March 7, 2014, 10:58 PM   #21
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What is the purpose of a bull barrel?

Quote:
Dc777 asked:

What are the benefits of a bull barrel?


Dc,

1:


2:
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Old March 8, 2014, 07:15 AM   #22
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Dremel-- That is not what I said. Heat will affect accuracy. I said the ability to shoot more rounds BEFORE barrel heat up.
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Old March 8, 2014, 07:18 AM   #23
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I primarily shoot bull barrels in long guns just because once a pencil barrel heats up, they tend to flex slightly more. Plus the heat dissipation is better with a bull barrel.
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Old March 8, 2014, 10:02 AM   #24
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Right, meaning they

ARE

in fact more accurate when hot. Period. (Generally speaking). Not a fable. Not a myth. Fact.

I think what some of you mean is "Thick barrels aren't any more accurate than thin barrels WHEN COLD". Which is true. But you have to say those last two all-important qualifying words. You can't just make the blanket statement that "Thick barrels aren't any more accurate than thin barrels." Without those last two words, the truth value overall goes from true to false.
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Old March 8, 2014, 10:07 AM   #25
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I keep seeing that bull barrels don't heat up as much. Well...a sequence of rounds fired in a thin barrel or a fat barrel will produce the same amount of heat. The bore is going to be just as toasty either way. It is possible, however, that the greater amount of metal in the fat barrel will draw heat from the surface of the bore faster than the smaller amount of metal in the thin barrel will. But, on the other hand, the thin barrel may shed the heat to the air faster than the fat barrel will.
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