Long throat & barrel erosion

[Mr.Snerdly]

I was discussing the erosion of the barrel on my Axis with a guy and he has a theory that a barrel with a long throat would erode faster than a shorter one. I don't know if this is true but the Axis did erode at a rate nearly 9 times the rate of the other 223.

I also have a fairly good estimate of how many rounds was through it. I didn't start shooting, at least as much as I do now, until fairly recently. I looked at all of the bullets I bought from various suppliers and the total number of bullets is right at 3200. The 3200 would be divided up among three 22 caliber rifles and the Axis was the last one I bought. There is no way it could have over 1500 rounds through it. It has never used factory ammo, everything was handloaded at between min and max load using Hodgdon data. Probably 3/4ths of the time I used CFE 223, probably 20% of the time 3031 and the remainder something else.

Any opinions on the long throat erosion idea?

[Whynot]

I don't think it's the long throat that is the issue- but the relationship between the throat and bullet. If the bullet has a long way to travel before it seals up the barrel then it is going to let more hot gas around it and that will cause more erosion. I have some barrels with very long throats- but they shoot heavy for caliber bullets- and they don't seem to wear fast.

Also- boat tail bullets cause more erosion than flat base because of how they funnel the gas to the sides.... as well as bullet construction and how easily they bump up and seal the bore..... so it has a lot more variables than just round count.

[charlie b]

What he said would be a theory for me as well.

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[Mr.Snerdly]

That is interesting that boat tail bullets are harder on barrels. A lot to think about. I have also heard heavier bullets are harder on barrels. You would think with more powder on the lighter bullets they would be worse but some say the gases have more time to do their damage since the bullet moves slower.

[tomme boy]

The powder type and amounts are the main culprit of erosion. Certain powders just wear out a barrel faster than others. Particularly IMR powders.

[charlie b]

Heavier bullets can be harder on the barrels, if the jump is the same as a lighter bullet.

Takes longer to get moving, so longer to seal the barrel.

Yep, powder types and powder charges matter as well.

I put a ton of rounds through my .223 barrel, most of them 77gn and large charges of Varget, with a little jump. One of these days I need to measure the throat to see how much it actually changed. I never changed how far out I seat the bullets in over 4000 rounds.

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[sharpshooter]

Bullets have little or nothing to do with barrel erosion. Heat is what kills barrels.

[Robinhood]

...and poor metallurgy.

[Mr.Snerdly]

...and poor metallurgy.

Could it be possible that my Axis for one reason or another had defective material in the barrel? I don't know as much as I would like about barrels are made but I believe the regular ones are made of 4140. I don't know if the steel comes to them with a hardening process or not but would think it would if it does go through a heat treatment process. I would think if they did it after the machining and rifling the heat would distort the barrel. I had a 243 Savage that also wore out the barrel but the 243 is much harder on barrels and I would say it probably lasted about what one would expect for the caliber so I believe Savage, on average, have decent barrels. My other 223, which fired roughly the same amount and was treated the same with regard to cleaning, bullets and powder wore far less. The Axis wore .070" compared to .008" for the other rifle. Something doesn't make sense that there could be that much difference.

[Dave Hoback]

Could it be possible that my Axis for one reason or another had defective material in the barrel? I don't know as much as I would like about barrels are made but I believe the regular ones are made of 4140. I don't know if the steel comes to them with a hardening process or not but would think it would if it does go through a heat treatment process. I would think if they did it after the machining and rifling the heat would distort the barrel. I had a 243 Savage that also wore out the barrel but the 243 is much harder on barrels and I would say it probably lasted about what one would expect for the caliber so I believe Savage, on average, have decent barrels. My other 223, which fired roughly the same amount and was treated the same with regard to cleaning, bullets and powder wore far less. The Axis wore .070" compared to .008" for the other rifle. Something doesn't make sense that there could be that much difference.

Absolutely there could be an issue with the barrel from the factory. It’s. Always a possibility.


Savage just specifies Carbon Steel for the barrels, however, it likely is 4140. They make the barrels from round Bar-Stock. No, it doesn’t come hardened or anything. They perform every process, drilling, reaming, button rifling & lapping. The barrels aren’t “heat treated” per say, rather they are stress relieved after button rifling process, also called Normalizing. This entails heating to a certain temp below Austenitizing temperature; usually a little over 1,000F, for a period of time. And hour or so.

Here is a video from Savage showing & explaining their processes.
https://www.youtube.com/watch?v=EUkekGATrfQ

[Whynot]

Bullets have little or nothing to do with barrel erosion. Heat is what kills barrels.

I'm interested in the research that you have done to be able to rule bullet shape/construction out of it? Heat is a huge part of it..... where that heat is focused is also huge. It is the reason that a 6mm Rem will have better barrel life than a 243 win if you shoot the same bullet at the same pressure-- because the 243 neck/shoulder focus the gas to the sides as it comes out of the case.... and the 6mm rem with the shoulder and longer neck focuses the gasses and unburnt powder down the bore. Why is the 243 a notorious barrel burner when cartridges that have more powder capacity and speed have better barrel life? Because of where it focuses the destructive heat.... and boat tailed bullets by their design also work as a funnel to direct the gasses to the side of the barrel instead of down the bore.

I'm always interested in learning new things- and lots of shooting lore has been debunked....

[Dave Hoback]

Well, Many 243 loads are using the lighter bullets at laser beam velocity. 3500, 3600, even 3900fps+ from factory loaded 243Win. The 6mm Remington was designed for the heavy(at the time) projectiles. Can’t really find 6mmRem with light bullets & loaded to insane velocity. It’s those light projectile loads at high velocity roasting barrels. It’s a common Overbore situation. The 243Win loads using 100gr pills at 2950fps are not responsible for the it being labeled a Barrel Burner. Feed your 6mmRem a steady diet of 65gr V-max at 3800, or 3900fps and see how long the barrel lasts.

[Whynot]

Well, Many 243 loads are using the lighter bullets at laser beam velocity. 3500, 3600, even 3900fps+ from factory loaded 243Win. The 6mm Remington was designed for the heavy(at the time) projectiles. Can’t really find 6mmRem with light bullets & loaded to insane velocity. It’s those light projectile loads at high velocity roasting barrels. It’s a common Overbore situation. The 243Win loads using 100gr pills at 2950fps are not responsible for the it being labeled a Barrel Burner. Feed your 6mmRem a steady diet of 65gr V-max at 3800, or 3900fps and see how long the barrel lasts.

Backwards....the 6mm (244) was designed for light bullets and lost the popularity contest to the 243 because it couldn't do the dual purpose role (varmint and deer) as well as the 243. The 244 (6mm) had a 1-12 and the 243 had a 1-10. Looking at factory loads doesn't do much good because the 6mm Rem just isn't popular enough to have the ammo support that the 243 does. But hand load them with the exact same bullet and the 243 still has shorter barrel life (in equal barrels).

Also- lots of discussion about bullet weight and barrel life..... my view is that heavy bullets are actually harder on barrels than light bullets. The light bullets start and travel faster so they have less dwell time in the barrel than heavy bullets-- even though light bullets have more powder behind them and more velocity.