Are light rifle barrels inherently not accurate?

[d_holliday]

But for many shooters, the gun will still be more accurate than the operator.

An old hunting guide once told me that my rifle will always be a better marksman than me.

 

[pronstar]

Assuming both barrels are made of the same material:
A heavier barrel will take more energy to heat-up.
And it’s mass means it will retain this heat longer.

It’s just physics and there’s a calculation for it:

heat = specific heat of substance x mass x temp change

Specific heat will be a constant since we’re comparing the same metal. So the variables are mass and temperature change.


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[Coop45]

That's because the pedal depressed pan-chromatic resonance effect doesn't occur until after the 21st shot.

Is that why ammo comes in 20 rd boxes?

 

[oldag]

The law of inertia in physics: heavier objects are more resistant to movement, ie wind currents pressing against the side of barrel. As a military truck mechanic, and later an automobile mechanic by trade, I was schooled that thicker brake drums and rotors dissipate heat faster, more metal, than thinner ones so thicker drums/rotors are less prone to brake fade than thin ones due to less heat buildup. All drums/rotors are made of steel as is all gun barrels.

Also a lighter barrel is going to be more sensitive to a shooter that has jittery hands or a jittery trigger finger and is more likely to move off target when the rifle is fired. Heavier guns like heavier vehicles are inherently more stable with added mass. A big, heavier car is smoother running than a lighter car over the same bumpy road at the same speed. This is why heavier guns recoil less: added mass makes them more inert, resistant to movement from the thrust of the discharging bullet and propellant gasses.

On the other hand, more weight levered out on the barrel end, the more difficult to hold steady.

We are not talking huge differences here.

 

[d_holliday]

On the other hand, more weight levered out on the barrel end, the more difficult to hold steady.

We are not talking huge differences here.

It could be that heavy barrels are just a way for gun makers to get more of people's money. A sales gimmick. On the bench the rifle is going to be supported on sandbags. A heavy barrel might be great for winning matches or shooting long-range varmints on a Harris bipod. I can't see any use for it for tactical reasons or for hunting deer. My army M16's never had heavy barrels. In basic training my tired arms sagged enough as it was with my M16A1 during a 15 mile road march. The drill sergeant kept yelling at me to get my muzzle up at port arms under the threat of an Article 15. That stupid weapon was only 6.50 pounds dry. One of my sergeants told me not to use my M16 barrel as a lever or a cheater bar for assembling army cots as it would bend the barrel. It was awfully difficult to get that end bar in place on the cot. The cot fabric had to be stretched real tight for enough clearance to get the tab into the hole. I was tempted to use my weapon as a lever for this for prying the end bar into place right at the corner. A rifle is no pry bar though army manuals say M16's can be used as improvised leg splints for casualties.

 

[deemus]

A heavy barrel might be great for winning matches or shooting long-range varmints on a Harris bipod. I can't see any use for it for tactical reasons or for hunting deer.

Tactical hunting? 230 yd shots on varmints? Heavy long barrel works wonders.

 

[d_holliday]

Tactical hunting? 230 yd shots on varmints? Heavy long barrel works wonders.

tactical use or hunting, tactical use = personal defense weapon as in AR-15, doesn't the front sight get in the way of your view when a scope is mounted on the pic rail after the carry handle is removed? Does the rifle have to be re-zeroed each and every time the carry handle and/or pic-rail mounted scope is removed and reinstalled?

 

[candcallen]

Not going to do it.

 

[jetcycles]

Both barrel profiles serve their purpose as tools in my world. Barrel profiles aside, and in my humble opinion, all rifles should be tested for accuracy with various loads in order to determine what works best for that rifle. The cost of getting into a sub moa rifle with factory ammo is getting lower and lower these days, shoot whatever makes you happy as the end user is often the determining factor in accuracy anyway.

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[TheDan]

I was schooled that thicker brake drums and rotors dissipate heat faster, more metal, than thinner ones so thicker drums/rotors are less prone to brake fade than thin ones due to less heat buildup.

A heavier barrel will take more energy to heat-up.
And it’s mass means it will retain this heat longer.

You're both right. Dissipation is a matter of perspective; from what to what.

 

[Axxe55]

The quality of the rifling has more to do with accuracy that the diameter of the barrel.

 

[G O B]

Heavy barrel is a nlarger heat sink (more mass=ability to sink more heat), so less stringing with repeated shots.
BUT- accuracy has more to do with HARMONICS than mass.

 

[DyeF9]

The law of inertia in physics: heavier objects are more resistant to movement, ie wind currents pressing against the side of barrel. As a military truck mechanic, and later an automobile mechanic by trade, I was schooled that thicker brake drums and rotors dissipate heat faster, more metal, than thinner ones so thicker drums/rotors are less prone to brake fade than thin ones due to less heat buildup. All drums/rotors are made of steel as is all gun barrels.

A thicker barrel will not necessarily dissipate heat faster. It will heat slower and distribute the heat through more mass. You need more surface area to dissipate heat faster. Thinner surfaces assists with that, such as fluted barrels or fancy heat sinks.

 

[Axxe55]

A thicker barrel will not necessarily dissipate heat faster. It will heat slower and distribute the heat through more mass. You need more surface area to dissipate heat faster. Thinner surfaces assists with that, such as fluted barrels or fancy heat sinks.

Kind of why they put fins on radiators. To increase surface area to dissipate heat faster.

 

[zackmars]

tactical use or hunting, tactical use = personal defense weapon as in AR-15, doesn't the front sight get in the way of your view when a scope is mounted on the pic rail after the carry handle is removed? Does the rifle have to be re-zeroed each and every time the carry handle and/or pic-rail mounted scope is removed and reinstalled?
View attachment 223522

If the optic has magnification, the front sight will be a slight smudge, you wont see it. If you have a detachable carry handle, just get a proper optic mount that lets you have a proper cheek weld

 

[DyeF9]

Kind of why they put fins on radiators. To increase surface area to dissipate heat faster.

Yep. Easier to get heat exchange off a thin large surface. JP Industries makes some actual finned heat sinks for their competition guns. They're same principal as a radiator or a heat sink on a computer processor

 

[pronstar]

Sorta funny...my 10/22 has a bull barrel and it’s ridiculously thick/heavy.

I dunno if there’s an advantage to so much barrel mass while shooting such a tiny round...


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[Vaquero]

Rate of fire matters a little.

That said, I have an all weather ultra light that hits consistently sub moa on three consecutive shots from cold bore. Ambient temperatures don't matter.

It won't win a match. I don't think.
It will make kill shots with boring consistency.

Handloaded ammo btw.

 

[Axxe55]

A person has to define accuracy and exactly what it applies to. A rifle that will consistently put rounds in the kill zone of an animal all day long, would hardly be considered accurate by those shooting benchrest competition.

 

[Maverick44]

Are light barrels inherently not accurate? Depends on what you want to do with them. If my goal was to shoot tiny little groups at 500 yards, a pencil barrel is not going to serve me very well due to how fast it's going to heat up. If I'm doing something more practical where I don't care about obsessing over tiny little groups, then the pencil barrel might serve me well.

There used to be a time when thin pencil barrels really had major issues when they heated up. Like serious POI changes. The metallurgy of those barrels has improved greatly over the last 50-60 years though. Nowadays, a quality thin barrel will not have a noticeable POI shift. Will your groups open up after a mag? Sure. More so than a heavy barrel? Yep. Does it matter in the practical sense? Not really. Within realistic distances under realistic circumstances with a realistic expectation of accuracy, a pencil barrel will do fine. It's groups are not going to open up so much that they become an issue. The guys who run InRange TV both shoot ARs equipped with pencil barrels. They have done a lot of testing and have shot (and scored very well) in a lot of competitions geared towards practical shooting with those rifles. Their conclusion was that a pencil barrel is not a detriment, and that the accuracy of the barrel is more than sufficient for practical shooting. My conclusion is the same. I built an AR with a pencil barrel, and it's probably my favorite AR. It's super light and quick handling, and it is what I would consider to be accurate. It's not going to shoot 1/2" groups at 200 yards, but it's more than accurate for just about anything the AR was designed to do.

The deal with heavy barrels is that they heat up slower. There's less change from shot to shot, which can result in tighter groups if care is taken in getting very uniformly made ammo. That is the key to precision. Uniformity. The less change there is between shots, the more precise the shot is going to be. They don't cool off faster. The pencil barrel is actually going to cool faster due to it's smaller mass.

What you plan on doing with the gun will determine which barrel is right for you and your needs. They both have a purpose, and they both excel at that purpose.