Accuracy comparisons of heavy barrel vs. standard?
- Thread starter wahoowad
- Start date
Originally Posted By: pepaf100I was thinking of having it cut because it is so front end heavy it is uncomfortable to carry thinking of cutting it down to 20inch would I have any problems with the gas length an accuracy if there was a chance I would get another barrel an sale this one thanks
Going to 20" will be compatible with any gas set up. Your accuracy should be maintained given a decent crown.
Greg
Going to 20" will be compatible with any gas set up. Your accuracy should be maintained given a decent crown.
Greg
Originally Posted By: CommodorefirstJust to clarify for folks, barrel thickness generally does not matter in regards to accuracy, for the first few shots.......after that it does.
It matters greatly for heat (expansion and contraction) and stiffness. And when the barrel heats up if it is a sporter or lightweight barrel, things go quickly south in the accuracy department. A thicker barrel also tends to help the shooter and minimize their effects on accuracy (how they hold the gun, tight vs loose grip, how good is their bench technique, how firm is the cheek weld.) Try this sometime when shooting, try a light cheek weld vs a firm cheek weld in the middle of the group, followed by firm vs loose shoulder, a lot of times the gun will shoot differently on each of these methods of holding. The Barrel vibrations on a shot are affected by a lot of things and on a thicker barrel you do get generally more consistency,
I have two lightweight select match shilen barrels, one on my custom .308 hunting rifle, the other one is a sporter select match on my custom .35 whelen. On the .308 and it is a lightweight contour (Pencil thin!) it is equal in accuracy for the first two shots to my .30 cal benchrest hunter gun with a number 7LV taper. The third shots starts to spread slightly to maybe a half inch group, and after that, all bets are off.
Generally folks shoot heavier guns better, recoil is less, and after several shots the heating up of the barrel and other factors make it seem apparent that the heavy barrels are more "accurate" but in reality, if I was to shoot a shot every 15 minutes in the same conditions I can get super groups from my pencil thin select match barrels too, but how practical is that?
Wade
There is one technical aspect to barrel weight, and that is the way a barrel will "whip" as the bullet passes through, lighter barrels have more whip than heavier ones, and the harmonics determine what stage of whip the barrel is at as the bullet leaves the lands. This is what accounts for why cutting an inch or two off of a barrel might improve accuracy (along with recrowning).
Slow motion photography of what a barrel does as the bullet goes through is pretty amazing.
It matters greatly for heat (expansion and contraction) and stiffness. And when the barrel heats up if it is a sporter or lightweight barrel, things go quickly south in the accuracy department. A thicker barrel also tends to help the shooter and minimize their effects on accuracy (how they hold the gun, tight vs loose grip, how good is their bench technique, how firm is the cheek weld.) Try this sometime when shooting, try a light cheek weld vs a firm cheek weld in the middle of the group, followed by firm vs loose shoulder, a lot of times the gun will shoot differently on each of these methods of holding. The Barrel vibrations on a shot are affected by a lot of things and on a thicker barrel you do get generally more consistency,
I have two lightweight select match shilen barrels, one on my custom .308 hunting rifle, the other one is a sporter select match on my custom .35 whelen. On the .308 and it is a lightweight contour (Pencil thin!) it is equal in accuracy for the first two shots to my .30 cal benchrest hunter gun with a number 7LV taper. The third shots starts to spread slightly to maybe a half inch group, and after that, all bets are off.
Generally folks shoot heavier guns better, recoil is less, and after several shots the heating up of the barrel and other factors make it seem apparent that the heavy barrels are more "accurate" but in reality, if I was to shoot a shot every 15 minutes in the same conditions I can get super groups from my pencil thin select match barrels too, but how practical is that?
Wade
There is one technical aspect to barrel weight, and that is the way a barrel will "whip" as the bullet passes through, lighter barrels have more whip than heavier ones, and the harmonics determine what stage of whip the barrel is at as the bullet leaves the lands. This is what accounts for why cutting an inch or two off of a barrel might improve accuracy (along with recrowning).
Slow motion photography of what a barrel does as the bullet goes through is pretty amazing.
Originally Posted By: NM LeonThe pressure developed during the ignition of the propellant in a cartridge causes ALL barrels to bend in a reaction that's like waves travelling towards the muzzle (harmonics).
For accuracy, you must do everything possible to ensure that the bullet leaves the muzzle when the muzzle is at exactly the same point in the wave with every shot.
To get the bullet to exit the muzzle at exactly the same barrel bending point every time is virtually impossible. The variables that will change this include tiny variations in powder weight, primer ignition speed, bullet weight, cartridge case consistency, ambient air temperature, humidity, etc, etc, etc. The quest for accuracy is one of trying to strictly control as many of those variables as possible, but it's impossible to control them all perfectly.
Stiffer barrels are more accurate than more flexible barrels because the bending reaction to the pressure wave caused by ignition are less. When those inevitable variations in harmonics occur, they will have a smaller effect in a stiff barrel than than they would with a more flexible barrel.
A thicker barrel is stiffer than a thin barrel of the same length. A short barrel is stiffer than a long barrel of the same diameter, but sometimes a longer barrel is needed in order to get a complete burn of the powder needed to achieve the desired muzzle velocity.
Firing a string of shots heats up the barrel and changes the tensile characteristics of the steel, causing a different physical reaction to the pressure wave generated by ignition, meaning the bullet will be exiting the barrel at a different nodal point. A thicker barrel is less susceptible to this since it takes longer to heat up.
While it is certainly possible that a specific long pencil barrelled rifle might out shoot a specific short bull barrelled rifle, the most accurate barrel, all else being equal, will be the stiffest/shortest barrel that will still allow the desired muzzle velocity.
Oops I didn't see that when I posted my thing on harmonics. I have tried a harmonic adjuster on an Anschutz 1517 MPR and it closed up 5/16ths inch groups to 1/4 inch.
For accuracy, you must do everything possible to ensure that the bullet leaves the muzzle when the muzzle is at exactly the same point in the wave with every shot.
To get the bullet to exit the muzzle at exactly the same barrel bending point every time is virtually impossible. The variables that will change this include tiny variations in powder weight, primer ignition speed, bullet weight, cartridge case consistency, ambient air temperature, humidity, etc, etc, etc. The quest for accuracy is one of trying to strictly control as many of those variables as possible, but it's impossible to control them all perfectly.
Stiffer barrels are more accurate than more flexible barrels because the bending reaction to the pressure wave caused by ignition are less. When those inevitable variations in harmonics occur, they will have a smaller effect in a stiff barrel than than they would with a more flexible barrel.
A thicker barrel is stiffer than a thin barrel of the same length. A short barrel is stiffer than a long barrel of the same diameter, but sometimes a longer barrel is needed in order to get a complete burn of the powder needed to achieve the desired muzzle velocity.
Firing a string of shots heats up the barrel and changes the tensile characteristics of the steel, causing a different physical reaction to the pressure wave generated by ignition, meaning the bullet will be exiting the barrel at a different nodal point. A thicker barrel is less susceptible to this since it takes longer to heat up.
While it is certainly possible that a specific long pencil barrelled rifle might out shoot a specific short bull barrelled rifle, the most accurate barrel, all else being equal, will be the stiffest/shortest barrel that will still allow the desired muzzle velocity.
Oops I didn't see that when I posted my thing on harmonics. I have tried a harmonic adjuster on an Anschutz 1517 MPR and it closed up 5/16ths inch groups to 1/4 inch.