How to tell if barrel is worn out?
- Thread starter millwright
- Start date
If everything is as you described than it is not worn out. It would take millions of rounds to worn out barrel. Barrels get destroyed due to combination of chemical reaction and mechanical friction in which case would (over the time) develop visible signs of corrosion and erosion. Only in cases where high rate of fire is present you can wear out barrel in a short period of time. Like MG 42 which theoretical rate of fare is 21 bullets per second. Not practical because if you try to achieve it, it would destroy barrel for sure. It would require you to constantly feed weapon for a full minute at least, and during that time barrel would become red hot and rendered useless/destroyed.
But how to tell that barrel was polished to cover up visible signs of damage, very difficult task. You need an aye, experience, time, and bore scope. You can slug it and measure, get the feel of it while slugging, but no one will let you play with gun before purchase. So this approach would be useless to you.
But how to tell that barrel was polished to cover up visible signs of damage, very difficult task. You need an aye, experience, time, and bore scope. You can slug it and measure, get the feel of it while slugging, but no one will let you play with gun before purchase. So this approach would be useless to you.
If you have an accuracy problem it could be caused by many things , with the last and maybe most expensive being the barrel. But having said that there a certain calibers that eat barrels regularly, they are just real hard on barrels. If you list your caliber and why you suspect your barrel is worn out, maybe you could get some positive input, there are quite a few very experienced shooters on this site.
Perhaps the best indicator is a falling off in the accuracy of the barrel. Target rifle shooters notice groups becoming vertical at long range; this results from increasing variation in muzzle velocity. If a barrel is well cleaned, you can observe throat erosion - right where the lands start - quite easily . This doesn't mean that the barrel is no longer shooting satisfactorily, but does indicate that there is significant wear. Some use borescopes, or plug gauges. Handloaders will notice that bullets must be seated further out to reach the rifling. Barrel life is dependent on the intensity of the round, to a great extent. A .308 barrel may be competitive for 5000+ rds, and give hunting acccuracy for 10 000 or more. A 6.5x.284 for 1500 or 2000. A .38 Special for untold thousands. Usually a barrel wears out at the throat first from a combination of erosion and heat; the passage of the bullet does not contribute much to wear. It is not uncommon for a barrel to be set back and rechambered to eliminate the eroded section. For many high intensity centrefire cartridges, the accurate lifespan of a barrel is 6 - 8 seconds. Take the number of milliseconds that it takes a bullet to pass through a barrel, multiply by some thousands, and the barrel's accurate lifespan can be measured in seconds. There have been military tests done to determine the number of rounds before the barrel will no longer stabilize a bullet, and it tumbles. This can take a very large number of rounds, although useful accuracy would have disappeared rather early on.
Accurate life could also be measured in pounds
Another way to look at it ... For say a 300WSM using 70gr. of RL22 per round.
100 rounds would be 1 lb of powder, and 2000 rnds would be 20lbs of powder.
This might be the useful target life of this barrel...20 lb of RL22.
NormB
tiriaq said:
Another way to look at it ... For say a 300WSM using 70gr. of RL22 per round.
100 rounds would be 1 lb of powder, and 2000 rnds would be 20lbs of powder.
This might be the useful target life of this barrel...20 lb of RL22.
NormB
What usually happens is the muzzle of a rifle will become worn down by careless/improper cleaning causing a lack of accuracy. People usually clean a rifle in a certain way, oblonging the muzzle. Be care with that cleaning rod!
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- In the middle of gopher country
After wearing out 3 barrels of 22-250 caliber, I'm still no expert. However, the 3 consistent things that I've noticed are:
1-- Accuracy starts to degrade to the point where you don't know where the point of impact will be. From an inch to as far as 3 inches has happened to me.
2-- If you really look closely in good light, you can see the steel eroded from the throat.
3-- The lands get so far down the barrel and worn that it is impossible to seat the bullet on the lands.
In all of the above cases I've had the barrel checked by Ron Smith, Torrington with a bore scope. The surface of the steel looks like a dried mud flat. There are gouges and scrathes everywhere in the first 6 inches or so.
It isn't any wonder that this happens. Skin temperature of the bore steel is at approximately 15,000 degrees for a nanosecond during the powder burn. Temperatures will vary dependant upon the amount of powder and rate of burn.
1-- Accuracy starts to degrade to the point where you don't know where the point of impact will be. From an inch to as far as 3 inches has happened to me.
2-- If you really look closely in good light, you can see the steel eroded from the throat.
3-- The lands get so far down the barrel and worn that it is impossible to seat the bullet on the lands.
In all of the above cases I've had the barrel checked by Ron Smith, Torrington with a bore scope. The surface of the steel looks like a dried mud flat. There are gouges and scrathes everywhere in the first 6 inches or so.
It isn't any wonder that this happens. Skin temperature of the bore steel is at approximately 15,000 degrees for a nanosecond during the powder burn. Temperatures will vary dependant upon the amount of powder and rate of burn.
