Question: Does shooting heavy bullets reduce barrel life?

[Webster]

A far bigger factor in barrel life than bullet bearing surface is the amount and velocity of the 5000 degree plus hot gas jetting down the rifle barrel.
As larger powder charges are used with lighter bullets, and they go down the barrel faster than heavy bullets, it stands to reason that hot varmint type loads will give less barrel life than hot target loads with heavier long range bullets.

Sounds correct to me. It's called hot gas erosion. Nothing to do with the bullet bearing surface rubbing on the bore. It's not mechanical friction wear. Might have something to do with the hot gas being in the bore longer with a heavy bullet. At the range I try to space the shots 1 min apart. The barrel stays cooler. Don't shoot hot loads. I have 4000 shots in my 6BR and it still shots small groups (non comp practice). I don't push the speed. Bore scope looked like 1000 shots with actual 4000. 58 Gr bullets 3550 fps.

 

[gunsandgunsmithing]

Just like breaking in a barrel, heat and duration do 99% of the work. Friction is nil by comparison.

 

[Beau]

Long, heavy bullets wear bores faster than short, light bullets.

Why? Because long, heavy bullets take more time to engrave and spend more time in the throat. This increased dwell time increases the heat soaked by the throat. Heat is what destroys the throat, and throat wear is what, as a rule, destroys accuracy. Keep in mind that accuracy can also be destroyed by loose bullets that allow gas cutting the length of the bore and by gas leaking past the bullet at the muzzle. But weight & length don't affect those.

To cut down on heat soak in the throat you can use cooler burning powders and lubricate the bullet (moly, Danzac) to help ease & speed up engraving.

 

[fredo]

Required barrel twist rate and resultant bullet RPM has gotta be a factor in heat transfer, no?

22-243AI, 75gr @ 3600 from a 1:8 = 324,000RPM

22-243AI, 60gr @ 4150 from a 1:12 = 249,000RPM

If heat is what kills a barrel, which one of the above is transferring more heat to the barrel?

Reckon the slower rpm will generate & transfer less heat...no?

 

[Bart B.]

Check my bore capacity and barrel life table in:

http://forum.accurateshooter.com/threads/barrel-life.3943336/

 

[Beau]

Required barrel twist rate and resultant bullet RPM has gotta be a factor in heat transfer, no?

22-243AI, 75gr @ 3600 from a 1:8 = 324,000RPM

22-243AI, 60gr @ 4150 from a 1:12 = 249,000RPM

If heat is what kills a barrel, which one of the above is transferring more heat to the barrel?

Reckon the slower rpm will generate & transfer less heat...no?

It's harder to get a bullet started in a tighter twist barrel. That means more dwell time in the throat and shorter barrel life all else being relatively equal.

 

[Bart B.]

It's harder to get a bullet started in a tighter twist barrel. That means more dwell time in the throat and shorter barrel life all else being relatively equal.

I don't think there's any dwell time (still; not moving) for bullets anywhere in the barrel after they start out of the case neck. They may slow down a little as they go from freebore into the angled throat (leade). I cannot find any data on the forces required to push a bullet full into the rifling. I'm thinking 200 to 300 pounds of force; about 5000 psi to 7500 psi in 22 caliber bores. May have to do a test.

What's the rifling angle (or ratio; bullet circumference to twist length) to a 30 caliber bullet in a 1:11 twist barrel?

Does a 1:8 twist in a 22 caliber barrel have rifling at a greater angle than that 1:11 twist 30 caliber barrel?

I doubt there's much gas jetting between bullet and bore after the first couple inches past the chamber mouth. Match barrel groove diameters are typically smaller than bullet diameters. Bullets upset to groove diameter in their first inch or two of travel. Why else do they leave copper wash all the way to the muzzle in rough bores?