Which rounds are "hard" on barrels?

Clevinger

New member
I hear some people say certain rounds are "hard" on barrels, like the 243.

Is there anything to that, and why does it occur?

If this is true, what rounds to be aware of?
 
It's mostly the speed of the round that makes a round hard on a barrel. They actually call them "barrel burners." Though sheer velocity is part of the equation, pressure is another part of it. High pressure can hurt the throat of your gun and the barrel.

The simple answer is that there's mechanical friction that happens when a bullet leaves the barrel. Where there is friction, there will be wear. If you wear the rifling too much, then it doesn't work as well.

As far as rounds to watch out for, I've always heard that 22-250 is pretty hard on barrels. I'm sure a few much more experienced riflemen will chime in with a few more.
 
Another term that is bandied about is 'overbore,' which seems to relate to the case capacity versus the diameter (caliber) of the barrel.

I dunno.

All things wear out, but I've never worn out a barrel. I definitely need to shoot more.
 
Rounds such as the 220 Swift are tough on barrels due to the tremendous amount of pressure and heat but also due to the large amount of unburned powder eroding the throat.
 
Large charge weights of fast burning powder a reloader may use in his recipe is one way of shorting a barrels life span. Throat erosion is a common term used amongst reloaders. As far as which bullet weight is the most probable cause. That Sir is beyond my expertize with the 243.
 
How many rounds in a lifespan can I expect for a 243 if I am letting it cool and not shooting too many rounds in succession?

800? 900? More?
 
At least 800-900 and probably much more than that if as you meantion you let it cool down. I guess it also depends on what you consider to be acceptable accuracy. And also on what kind of rounds your shooting. Light for caliber bullets (example 55 grain btips) with lots of powder behind them are harder on things (more friction from the extreme velocity and more heat from the greater volume of powder burning)
 
Most of the numbers you'll hear concerning how many rounds it takes to shoot out a barrel seem to come from bench rest and other target shooters. For a hunting rifle we won't see the accuracy decline like they do, our guns are not up to the accuracy standards of theirs and speaking for myself I'm not nearly as good a shot as them. Other factors also include shooting hotter burning powders and bullet weight. If you shoot fast moving lighter weight bullets it is harder on your barrel than shooting heavier bullets.
 
As barrels wear out from the breech end first from the hottest fire and highest pressure that erodes away metal and the muzzle end (where velocity's the fastest) has little if any wear, bullet speed has virtually nothing to do with barrel wear. Once the bullet's engraved, there's not much friction between it and the barrel.

But the number of rounds varies primarily with how well the rifle shooter and his hardware perform. Some folks are better shots than others. Some rifles are more accurate than others. And some ammo's a lot more accurate than others. The barrel life numbers will vary depending on which one of each is shooting along with the human's expectations. And extra hot, way too high pressure loads (over SAAMI specs) compound the issue.

Some years ago, I tracked barrel life for several calibers (bore diameters) and powder charges used for competition rifles and when their owners replaced their barrels. These folks had the most accurate rifles and shot them well enough to win the matches and set the records. All that data boiled down to a simple equasion.

If the powder charge weight in grains was the same number as the square millimeter area of the bore, barrel life was 3000 rounds before accuracy degraded by about 50%. A 1/4 MOA rifle at 100 yards (or a 3/4 MOA rifle at 1000 yards) would get a new barrel when accuracy was 50% bigger. Good example is the .308 Winchester with about 45 square millimeters of bore area and buning 45 grains of powder, barrel life was about 3000 rounds. That number is my number for bore capacity; the area of the bore in square millimeters equals powder charge for normal safe peak pressure loads at about 52,000 CUP or 62,000 PSI. Any more powder used in a cartridge was called an overbore capacity cartridge by my definitions.

Cartridges burning 40% more powder than bore capacity got half the barrel life. When twice bore capacity was used (huge 30 caliber magnums), barrel life was only 25% of 3000 rounds; 750, for example for the 7mm Rem Mag. My .264 Win Mag long range match barrel lasted 640 rounds.

Varmint and big game hunters typically accept less accuracy to start with for their barrels and they were happy with up to twice as many rounds; 6000 for cartridges at bore capacity for their bore size. Service rifles used for military combat situations had a much larger number for barrel life as their accuracy standards were less. Their bore erosion gauges maxed out at about 9000 to 10,000 rounds; three times that for a 30 caliber barrel's 45 grain bore capacity. And a big dangerous game hunter will be happy with his double barrelled .500 Nitro Express keeping its shots inside 2 inches at 50 yards all day long.

My numbers have been pretty much verified by Sierra Bullets' test barrels. Their 22 caliber and 30 caliber test barrels (.222 Rem and .308 Win.) both used powder charges about equal to their bore capacity of 22 and 45 grains respectively. They rebarreled their rail gun barrels used to test their bullets for accuracy at about 3000 rounds. When a new barrel was fitted, a special lot of bullets (called "standards") proved to shoot sub 1/4 MOA at 100 or 200 yards in their indoor test range would qualify that new barrel. Before testing new lot of bullets, some standards were shot with it to verify its accuracy. As long as those standards shot no worse than 40% bigger than they did when the barrel was new, that barrel was still accurate enough to accurately asses their production bullets. If that test with standards was close to 50% larger, that barrel was considered worn out for accuracy testing. That happened at about 3000 rounds for both their 222 Rem and 308 Win test barrels. Their .300 Win. mag barrel used to test heavy 30 caliber bullets got rebarreled at about 1200 rounds; its accuracy had dropped off enough to no longer qualify.

The powder's heat index also effects barrel life even when peak pressure's the same. Lower temperature powders give longer barrel life; higher ones, less. Quickload's data gives powder heat indexes for comparison.

Regarding the .243 Win., when it was first used in match rifle competition, barrel life amonst the top ranked folks was (and still is) about 1300 to 1500 rounds. Compared to about 800 for the 6.5x.284 used in competition, that's not bad at all. Hunters may well get twice that many rounds before they notice accuracy fall off.

For comparison, note that top ranked smallbore .22 rimfire rifle shooters rebarrel somewhere in the 30,000 round range.
 
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That's a very good point that I just never though of before Bart, about how on high velocity rounds the wear near the muzzle is minimal compared to the throat and therefore velocity itself is not the primary cause of barrel wear. Thanks. I guess it must just be because of the larger powder charges associated with shooting lighter projectiles to reach the same energies as slower moving heavier bullets. Learning new things/discovering what's right in front of me all the time.
 
Bart B.

Is it true then, that P.O. Ackley chose the 40 degree shoulder and the straight case wall in order to keep the unburnt powder in the case and as a result extend the life of the barrel throat?
 
Yes, sharper and larger diameter shoulders help. So does longer case necks. Both can add 10 to 20 percent to calculated barrel life. Such Ackley Imp'd cartridges typically hold more powder than when in their original shape which lessen barrel life right off the bat. The effect isn't linear.
 
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If you want maximum barrel life, keep the case volume and pressure down.

For example, you'll get more barrel life shooting a 7x57 instead of a 280 Rem loaded to the "7mm Express" level of pressure.

The other thing you can do, is for the same case capacity (within reason) is to increase the bore diameter. Running the 243 Win at the same pressure as a 358 Win will erode the throat more on the smaller bore as you are trying to push that much gas through a smaller pipe.

But barrels for high volume competition rifles just needs to be considered like tires for a race car. Once they are worn past useable, time to be replaced.

Jimro
 
Jimro, both the .243 and .358 operate at the same SAAMI max average pressure of 52,000 cup. The .243 is an overbore capacity round. .358's underbore and will have 3 to 4 times the barrel life at equal pressure.
 
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Clevinger,

Bart B seems to pretty well sum up the "facts" of the situation, however ------

Not in anyway saying your question is a bad or stupid one, and most of us have ask it at one time or another, but ----------------

Let us get some things into perspective here.

What are you going to use the barrel for? Are you needing gilt edge accuracy with every shot being the one that could put you in the money or 2nd place?

Most of us, no matter how well our factory barrel might shoot are not at that level.

Then let's face it. You can take a brand new rifle/barrel to the range and within a few shots find that it is a real keeper making nice round slightly over single bullet diameter 5 shot groups and you can leave the range an hour later with that barrel destroyed. Fried, burnt out, ruined!

You can take the best centerfire barrel ever made and destroy it in one session if your stupid.

However, most of us do not fall into either one of those groups, and therefore for most of us there might be better questions to ask.

Do you enjoy shooting?

Can you find time to punch a bit of paper or hunt some fuzzy little ground vermin with fair frequency?

Can you without breaking the bank afford to do the above activities?

If so, have at it and don't look back.

Are you wearing your barrel when you put high velocity rounds down the tube? Yep, without question, but likely the rig you got there with cost lots more and will be replaced much sooner and at a much higher cost then your rifle or barrel.

I've owned a beautiful RUGER #1 - 22/250 and used it! Wish I still had it!!

I've owned a number of .243s and used them!

In fact I now own a 243 RUGER 77 "flat bolt" of which I am at least the third owner.

I ask for the chance to buy it if my friend ever sold it because it shot so well.

And while it surely won't shoot as well now as it did 40 years ago it will still put the 55gr Nosler Ballistic Tips into a 1" 5 shot group at 100yds.

And I guarantee putting those little pills down the tube at 36 - 3700fps isn't increasing my barrel life any. I could have just let it set in the rack and shot the occasional group with some 100gr Nosler or Hornady bullets and maybe a shot or two during hunting season, but what would be the point?

"Barrel burner," or not I'd love to own a .220 Swift

And by the way, I saw 4000fps + for the first time from a rifle of mine when testing those 55gr pills in my old .243 with it's 22" barrel. Was that series of test shots barrel burners? Very likely, and I don't regret one shot.

I'm not a collector. My firearms are not collector level firearms. They are bought and made to use and that is what happens.

If your not an abuser and set to destroy a barrel just to see if you can do so, your time would be much better spent worrying about where to find brass, primers and bullets then to worry about shooting out your barrel.

THEN, should you be so lucky to finally shoot out a barrel, be thankful for the fact that you have spent a great deal of time in the field and just have your rifle rebarreled and make it your goal to live long enough to burn that one out with however many thousand rounds it may take.

Crusty Deary Ol'Coot
 
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Bart B.

That's why I used the 243 Win and 358 Win as an example of increasing the bore, but keeping the pressure the same, increases barrel life.

The whole family 243 Win, 260 Rem, 7mm-08, 308 Win, 338 Fed, 358 Win, could be grouped from "hardest on barrels" to easiest on barrels simply by going from smallest caliber to largest.

You could do the same with the 30-06 Family. 25-05, 270 Win, 30-06, 338-06, 35 Whelen, and if you load them all to the same capacity, as the bore increases the barrel lift increases too.

When comparing two loads in the same bore at the same pressure, the larger case capacity will operate at a lower pressure to get to the same velocity, so you can download a 7mm Rem Mag to 7x57 velocities and extend your barrel life quite a bit.

But there is no way to make a barrel last forever, even 22lr barrels will get shot out, but I think that is mainly from primer residues mechanically wearing away at the bore as multiple shots are fired per string. Sure takes a lot of trigger pulls to shoot out a rimfire barrel though.

Jimro
 
Jimro is right about rimfire 22 barrels. Primer residue rests at the bottom of the chamber throat and scrapes away steel starting at its bottom. A dark ring starts at 6 o'clock and works its way up each side to 3 and 9 o'clock. That's when the barrel should be set back 1.5 inch or replaced. Either way starts the rounds fired count at zero. Maybe 5000 or more if really erosive ammo was used and it "ringed" to 3 and 9 at 20,000 to 25,000 rounds.
 
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The more overbore the round is, the shorter the barrel life. Example: .264 win mag 800 rounds per barrel. , .458 win mag. you can not shoot one out.
 
With the. .458 Win bore capacity at 103 grains and typical charge weights inthe low 70's grain weights, I predict about 4000 rounds of pristine barrel life.
 
With the. .458 Win bore capacity at 103 grains and typical charge weights inthe low 70's grain weights, I predict about 4000 rounds of pristine barrel life.
No way I'm shooting 4000 rounds of 458 winchester so I sure ain't gonna be the one that wears one out.
 
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