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October 24th, 2013
We can predict, with some certainty, how long a light bulb will last (in use), or a shingle roof, or even a nuclear reactor. But how about barrels? Is there a way to reliably estimate barrel life based on known characteristics? This article explains one effort to quantify barrel life…
 How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need Excel or an Excel viewer to open the file.
Click to Download Spreadsheet: Barrel Life Spreadsheet (Latest Version)
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
 
Mike observes: “There has been alot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223rem to 300 UltraMagnum. Another element added, but turned off is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.”
NOTE: Mike says: “This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: We want to stress that Mike’s spreadsheet is a helpful tool, but it is not a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly warn us that some chamberings (such as the 6-284) are likely to be barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
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July 27th, 2012
How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need Excel or an Excel viewer to open the file.
Click to Download Spreadsheet: Barrel Life Spreadsheet (Latest Version)
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
Mike observes: “There has been alot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223rem to 300 UltraMagnum. Another element added, but turned off is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.”
NOTE: Mike says: “This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: We want to stress that Mike’s spreadsheet is a helpful tool, but it is not a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly put shooters on notice that some chamberings (such as the 6-284) are likely to be a barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
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September 16th, 2011
Here’s a little known fact that may startle most readers, even experienced gunsmiths: your barrel wears out in a matter of seconds. The useful life of a typical match barrel, in terms of actual bullet-in-barrel time, is only a few seconds. How can that be, you ask? Well you need to look at the actual time that bullets spend traveling through the bore during the barrel’s useful life. (Hint: it’s not very long).
Bullet-Time-in-Barrel Calculations
If a bullet flies at 3000 fps, it will pass through a 24″ (two-foot) barrel in 1/1500th of a second. If you have a useful barrel life of 3000 rounds, that would translate to just two seconds of actual bullet-in-barrel operating time.
Ah, but it’s not that simple. Your bullet starts at zero velocity and then accelerates as it passes through the bore, so the projectile’s average velocity is not the same as the 3000 fps muzzle velocity. So how long does a centerfire bullet (with 3000 fps MV) typically stay in the bore? The answer is about .002 seconds. This number was calculated by Varmint Al, who is a really smart engineer dude who worked at the Lawrence Livermore Laboratory, a government think tank that develops neutron bombs, fusion reactors and other simple stuff.
On his Barrel Tuner page, Varmint Al figured out that the amount of time a bullet spends in a barrel during firing is under .002 seconds. Al writes: “The approximate time that it takes a 3300 fps muzzle velocity bullet to exit the barrel, assuming a constant acceleration, is 0.0011 seconds. Actual exit times would be longer since the bullet is not under constant acceleration.”
We’ll use the .002 number for our calculations here, knowing that the exact number depends on barrel length and muzzle velocity. But .002 is a good average that errs, if anything, on the side of more barrel operating life rather than less.
So, if a bullet spends .002 seconds in the barrel during each shot, and you get 3000 rounds of accurate barrel life, how much actual firing time does the barrel deliver before it loses accuracy? That’s simple math: 3000 x .002 seconds = 6 seconds.
 Gone in Six Seconds. Want to Cry Now?
Six seconds. That’s how long your barrel actually functions (in terms of bullet-in-barrel shot time) before it “goes south.” Yes, we know some barrels last longer than 3000 rounds. On the other hand, plenty of .243 Win and 6.5-284 barrels lose accuracy in 1500 rounds or less. If your barrel loses accuracy at the 1500-round mark, then it only worked for three seconds! Of course, if you are shooting a “long-lived” .308 Win that goes 5000 rounds before losing accuracy, then you get a whopping TEN seconds of barrel life. Anyway you look at it, a rifle barrel has very little longevity, when you consider actual firing time.
People already lament the high cost of replacing barrels. Now that you know how short-lived barrels really are, you can complain even louder. Of course our analysis does give you even more of an excuse to buy a nice new Bartlein, Krieger, Shilen etc. barrel for that fine rifle of yours.
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October 21st, 2008
How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which there is not a lot of historical data.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need an Excel viewer to open the file.
Click to Download Spreadsheet: Barrel Life Spreadsheet (Lastest Version)
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
Mike observes: “There has been alot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223rem to 300 UltraMagnum. Another element added, but turned off is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.
NOTE: This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: We want to stress that Mike’s spreadsheet is a helpful tool, but it is not a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hard/hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly put shooters on notice that some chamberings (such as the 6-284) are likely to be a barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
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September 28th, 2008
For two years, Forum member John Skowron (John708) has been campaigning a 6BRX, built by Nat Lambeth (RustyStud). You’ll find the full history of John’s 6BRX project in this Forum Thread. With this rifle, John was the overall 1000-yard winner at Butner in February 2007.
The 6mm BRX is based on the 6mm BR cartridge. The shoulder is moved forward, but the shoulder angle and case taper is the same as the parent cartridge. This way you can use standard dies for most purposes (although it is a good idea to have a custom full-length die so you can size the entire case body). Many of our readers have been interested in the 6mm Improved (BRX, Dasher etc.), but they’ve wondered about case durability and barrel life. John has answers for those questions:
6BRX Case Life
Case life running the Berger 105s at 3000+ fps is 14-15 reloads. Brass was discarded when the primer pockets became too loose. The 6BRX brass OAL after fireforming is 1.56″. Max OAL for the 6BRX is 1.58″. The brass never stretched enough to require trimming before discard. Another plus for the 6BRX and Lapua brass. By the way don’t even bother with Remington-brand 6BR brass. The primer pockets were so loose after my standard fire-forming load I had to trash all the cases. Stick with the good stuff, Lapua.
6BRX Barrel Life
Here are Skowron’s comments as his round count increased:
2750 Rounds: I now have 2570 rounds through my 6mm BRX. I was just at the range today doing an accuracy test. I shot two 10-shot groups at 100 yards, one with 105gr Bergers, and the other with 107gr Sierras. Both were identical 0.44″ 10-shot groups. Not bad for a rifle with 2500+ rounds through it.
2900 Rounds: I now have 2900 rounds through my 6mm BRX. I was doing some load testing with the new 6mm Berger bullets. I compared them with my existing comp. load in my 6mm BRX. The 105gr Bergers, jammed .015″ into the lands, with 31.5 grains of Varget and Fed 205s are still shooting .45″ 10-shot groups at 100 yards. Velocity is 3060 fps. I don’t know how long this Broughton barrel will last, but I’m amazed that it’s lasted this long.
2950-3044 Rounds: I had virtually no throat erosion until I reached 2900 rounds. After 2900 rounds throat became noticeably rougher on cleaning and groups opened up. 10-shot groups with match ammo were now .53″ (compared to low fours before). At 2950 rounds the groups ran .58″. At 3044 rounds, the groups opened up to .7″. That’s not enough accuracy for LR work.
CONCLUSION: Barrel life with competitive accuracy was 2900 rounds with this gun.
Achieving this barrel life goal pretty much completes my 6mm BRX project. I’m now shooting a cartridge that has the same or better barrel life than the 260 Rem, it’s more accurate, with essentially equal wind drift. [Editor’s Note: Richard Schatz recently won the NBRSA 1000-yard Nationals with a 6 Dasher, a similar 6BR Improved cartridge, but with a 40° shoulder. Richard’s barrel had over 2000 rounds through it.]
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March 10th, 2008
How much does it cost you to send a round downrange? Ask most shooters this question and they’ll start adding up the cost of components: bullets, powder, and primers. Then they’ll figure in the cost of brass, divided by the number of times the cases are reloaded.
For a 6BR shooting match bullets, match primers, and 30 grains of powder, in brass reloaded a dozen times, this basic calculation gives us a cost per shot of $0.46 (forty-six cents):
Bullet $0.30 (Berger 105 VLD)
Primer $0.03 (Fed 205m)
Powder $0.08 (Varget @ $18.00/lb)
Brass $0.05 (Lapua priced at $60/100, 12 reloads)
Total $0.46 per round
$1.00 Per Shot True Cost? Yikes!
OK, we’ve seen that it costs about $0.46 per round to shoot a 6BR. Right?
Wrong! — What if we told you that your ACTUAL cost per round might be closer to double that number? How can that be? Well… you haven’t accounted for the cost of your barrel. Every round you fire down that tube expends some of the barrel’s finite life. If, like some short-range PPC shooters, you replace barrels every 700 or 800 rounds, you need to add $0.60 to $0.70 per round for “barrel cost.” That can effectively double your cost per round, taking it well past the dollar per shot mark.
Calculating Barrel Cost Per Shot
In the table below, we calculate your barrel cost per shot, based on various expected barrel lifespans.
 As noted above, a PPC barrel is typically replaced at 700-800 rounds. A 6.5-284 barrel can last 1200+ rounds, but it might need replacement after 1000 rounds or less. A 6BR barrel should give 2200-3000 rounds of accurate life, and a .308 Win barrel could remain competitive for 4,000 rounds or more.
The table below shows your barrel cost per shot, based on various “useful lives.” We assume that a barrel costs $500.00 total to replace. This includes $300.00 for the barrel itself, $160.00 for chambering/fitting, and $40.00 in 2-way shipping costs. Yes, you may have a smith that works for less, but these are typical costs shooters will encounter when ordering a rebarreling job.
The numbers are interesting. If you get 2000 rounds on your barrel instead of 1000, you save $0.25 per shot. However, extending barrel life from 2000 to 3000 rounds only saves you $0.08 per round.
NOTE: We assume component costs of $0.46 per round based on our 6BR example. If you shoot a larger caliber that burns more powder, and uses more expensive bullets and/or brass, your total cost per round will be higher.
How to Reduce Your TRUE Cost per Round
What does this tell us? First, in figuring your annual shooting budget, you need to consider the true cost per round, including barrel cost. Second, if you want to keep your true costs under control, you need to look at ways to extend your barrel life. This can be accomplished in many ways. First, you may find that switching to a different powder reduces throat erosion. Second, if you’re able to slow down your shooting pace, this can reduce barrel heat, which can extend barrel life. (A varminter in the field is well-advised to switch rifles, or switch barrels, when the barrel gets very hot from extended shot strings.) Third, modifying your cleaning methods can also extend the life of your barrel. Use solvents that reduce the need for aggressive brushing, and try to minimize the use of abrasives. Also, always use a properly fitting bore guide. Many barrels have been prematurely worn out from improper cleaning techniques.
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May 27th, 2007
For the past year, Forum member John Skowron (John708) has been campaigning a 6BRX, built by Nat Lambeth (RustyStud). You’ll find the full history of John’s 6BRX project in this Forum Thread. With this rifle, John was the overall 1000-yard winner at Butner in February 2007.
The 6mm BRX is based on the 6mm BR cartridge. The shoulder is moved forward, but the shoulder angle and case taper is the same as the parent cartridge. This way you can use standard dies for most purposes (although it is a good idea to have a custom full-length die so you can size the entire case body). Many of our readers have been interested in the 6mm Improved (BRX, Dasher etc.), but they’ve wondered about case durability and barrel life. John has answers for those questions:
6BRX Case Life
Case life running the Berger 105s at 3000+ fps is 14-15 reloads. Brass was discarded when the primer pockets became too loose. The 6BRX brass OAL after fireforming is 1.56″. Max OAL for the 6BRX is 1.58″. The brass never stretched enough to require trimming before discard. Anouther plus for the 6BRX and Lapua brass.
By the way don’t even bother with Remington-brand 6BR brass. The primer pockets were so loose after my standard fire-forming load I had to trash all the cases. Stick with the good stuff, Lapua.
6BRX Barrel Life
I now have 2570 rds through my 6mm BRX. I was just at the range today doing an accuracy test. I shot two 10-shot groups at 100 yards, one with 105gr Bergers, and the other with 107gr Sierras. Both were identical 0.44″ groups. Not bad for a rifle with 2500+ rounds through it.
Achieving this barrel life goal pretty much completes my 6mm BRX project. I’m now shooting a cartridge that has the same or better barrel life than the 260 Rem, it’s more accurate, with essentially equal wind drift. I’ll continue to post updates on barrel life. I think this barrel will last for another several hundred rounds.
Heavier Bullets
As far as shooting the DTAC 115s goes, I’ve temporarily abandoned that effort. The 105 Bergers, running 3050-3100 fps, give up very little wind drift to the 115s running at 2900-2950 fps. You might potentially get 3000 fps with the 115s using H4350 and throating the chamber to seat the bullets out. But since I very happy with the 105s and the way they’re performing at long range, I’m not going to change for now. [Editor’s Note: The Berger 105s in John’s latest reports were lot #559, from Berger’s new die.]
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February 16th, 2018
 So what does a “worn-out” barrel really look like? Tom Myers answered that question when he removed a 6.5-284 barrel and cut it down the middle to reveal throat wear. As you can see, there is a gap of about 5mm before the lands begin and you can see how the lands have thinned at the ends. (Note: even in a new barrel, there would be a section of freebore, so not all the 5mm gap represents wear.) There is actually just about 2mm of lands worn away. Tom notes: “Since I started out, I’ve chased the lands, moving out the seating depth .086″ (2.18 mm). I always seat to touch. My final touch dimension was 2.440″ with a Stoney Point .26 cal collet.”
Except for the 2mm of wear, the rifling otherwise looks decent, suggesting that setting back and rechambering this barrel could extend its useful life. Tom reports: “This was something I just thought I’d share if anyone was interested. I recently had to re-barrel my favorite prone rifle after its scores at 1,000 started to slip. I only ever shot Sierra 142gr MatchKings with VV N165 out of this barrel. It is a Hart and of course is button-rifled. I documented every round through the gun and got 2,300 over four years. Since I have the facilities, I used wire EDM (Electro Discharge Machining) to section the shot-out barrel in half. It was in amazingly good shape upon close inspection.”
Tom could have had this barrel set back, but he observed, “Lately I have had to increase powder charge to maintain 2,950 fps muzzle velocity. So to set it back would have only increased that problem. [And] I had a brand new 30″ Krieger all ready to screw on. I figured it was unlikely I’d get another full season on the old barrel, so I took it off.”
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February 26th, 2017
Here’s a little known fact that may startle most readers, even experienced gunsmiths: your barrel wears out in a matter of seconds. The useful life of a typical match barrel, in terms of actual bullet-in-barrel time, is only a few seconds. How can that be, you ask? Well you need to look at the actual time that bullets spend traveling through the bore during the barrel’s useful life. (Hint: it’s not very long).
Bullet-Time-in-Barrel Calculations
If a bullet flies at 3000 fps, it will pass through a 24″ (two-foot) barrel in 1/1500th of a second. If you have a useful barrel life of 3000 rounds, that would translate to just two seconds of actual bullet-in-barrel operating time.
Ah, but it’s not that simple. Your bullet starts at zero velocity and then accelerates as it passes through the bore, so the projectile’s average velocity is not the same as the 3000 fps muzzle velocity. So how long does a centerfire bullet (with 3000 fps MV) typically stay in the bore? The answer is about .002 seconds. This number was calculated by Varmint Al, who is a really smart engineer dude who worked at the Lawrence Livermore Laboratory, a government think tank that develops neutron bombs, fusion reactors and other simple stuff.
On his Barrel Tuner page, Varmint Al figured out that the amount of time a bullet spends in a barrel during firing is under .002 seconds. Al writes: “The approximate time that it takes a 3300 fps muzzle velocity bullet to exit the barrel, assuming a constant acceleration, is 0.0011 seconds. Actual exit times would be longer since the bullet is not under constant acceleration.”
We’ll use the .002 number for our calculations here, knowing that the exact number depends on barrel length and muzzle velocity. But .002 is a good average that errs, if anything, on the side of more barrel operating life rather than less.
So, if a bullet spends .002 seconds in the barrel during each shot, and you get 3000 rounds of accurate barrel life, how much actual firing time does the barrel deliver before it loses accuracy? That’s simple math: 3000 x .002 seconds = 6 seconds.
Gone in Six Seconds. Want to Cry Now?
Six seconds. That’s how long your barrel actually functions (in terms of bullet-in-barrel shot time) before it “goes south”. Yes, we know some barrels last longer than 3000 rounds. On the other hand, plenty of .243 Win and 6.5-284 barrels lose accuracy in 1500 rounds or less. If your barrel loses accuracy at the 1500-round mark, then it only worked for three seconds! Of course, if you are shooting a “long-lived” .308 Win that goes 5000 rounds before losing accuracy, then you get a whopping TEN seconds of barrel life. Anyway you look at it, a rifle barrel has very little longevity, when you consider actual firing time.
People already lament the high cost of replacing barrels. Now that you know how short-lived barrels really are, you can complain even louder. Of course our analysis does give you even more of an excuse to buy a nice new Bartlein, Krieger, Shilen etc. barrel for that fine rifle of yours.
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December 30th, 2014
We can predict, with some certainty, how long a light bulb will last (in use), or a shingle roof, or even a nuclear reactor. But how about barrels? Is there a way to reliably estimate barrel life based on known characteristics? This article explains one effort to quantify barrel life…
How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need Excel or an Excel viewer to open the file.
Click to Download Spreadsheet: Barrel Life Spreadsheet (Latest Version)
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
Mike observes: “There has been a lot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223 Rem to 300 UltraMagnum. Another element added, but turned off, is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.”
NOTE: Mike says: “This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: Mike’s spreadsheet is a helpful tool, but it is NOT a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly warn us that some chamberings (such as the 6-284) are likely to be barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
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September 20th, 2014
Put the same load in a variety of barrels (with the same length and chamberings) and you’ll see a wide variance in muzzle velocity. In fact, it’s not unusual to see up to 100 fps difference from one barrel to the next. We demonstrated this with a comparison test of Lapua factory ammo.
Chron Testing Lapua Factory Ammo
At our Southern California test range, we chronographed Lapua 105gr 6mmBR factory ammo in three different 8-twist barrels of similar length. The results were fascinating. Lapua specs this ammo at 2790 fps, based on Lapua’s testing with its own 26″ test barrel. We observed a speed variance of 67 fps based on tests with three aftermarket barrels.
Brand ‘S’ and Brand ‘PN’ were pre-fit barrels shot on Savage actions. Brand ‘K’ was fitted to a custom action. All test barrels were throated for the 100-108 grain bullets, though there may have been some slight variances in barrel freebore. With a COAL of 2.330″, the rounds were “jumping” to the rifling in all barrels. Among the four barrels, Brand ‘PN’ was the fastest at 2824 fps average — 67 fps faster than the slowest barrel. Roughly 10 fps can be attributed to the slightly longer length (27″ vs. 26″), but otherwise this particular barrel was simply faster than the rest. (Click Here for results of 6mmBR Barrel Length Velocity Test).
Results Are Barrel-Specific, Not Brand-Specific
These tests demonstrate that the exact same load can perform very differently in different barrels. We aren’t publishing the barrel-makers’ names, because it would be wrong to assume that ‘Brand X’ is always going to be faster than ‘Brand Y’ based on test results from a single barrel. In fact, velocities can vary up to 100 fps with two identical-spec barrels from the SAME manufacturer. That’s right, you can have two 8-twist, 26″ barrels, with the same land-groove configuration and contour, from the same manufacturer, and one can be much faster than another.
Don’t Demand More Than Your Barrel Can Deliver
We often hear guys lament, “I don’t get it… how can you guys get 2900 fps with your 6BRs and I can only get 2840?” The answer may simply be that the barrel is slower than average. If you have a slow barrel, you can try using more powder, but there is a good chance it may never run as fast as an inherently fast barrel. You shouldn’t knock yourself out (and over-stress your brass) trying to duplicate the velocities someone else may be getting. You need to work within the limits of your barrel.
Factory Ammo Provides a Benchmark
 If you have a .223 Rem, 6BR, .243 Win, 6.5×47 Lapua, 6.5×55, .308 Win, 30-06, or 300 WM Rifle, we recommend you buy a box of Lapua factory-loaded ammo. This stuff will shoot great (typically around half-MOA), and it can give you a baseline to determine how your barrel stacks up speedwise. When you complete a new 6BR rifle, it’s wise to get a box of the factory ammo and chronograph it. That will immediately give you a good idea whether you have a slow, average, or fast barrel. Then you can set your velocity goals accordingly. For example, if the factory 6BR ammo runs about 2780-2790 fps in your gun, it has an average barrel. If it runs 2820+ in a 26″ barrel (or 2835 fps in a 28″), you’ve got a fast tube.
Share the post "Life Lesson: Every Barrel is Unique. Same Load Registers 4 Different Velocities in 4 Different Barrels"
May 16th, 2024
Summer is coming soon, and temperatures are starting to heat up. We are already seeing unseasonably hot conditions in many areas of the country. You never want your barrels to get too hot, which can happen more quickly in summertime. Accuracy suffers when barrels over-heat, and excessive heat is not good for barrel life. So how do you monitor your barrel’s temperature? You can check if the barrel is “warm to the touch” — but that method is not particularly precise. There is a better way — using temperature-sensitive strips. McMaster.com (an industrial supply house) offers stick-on temp strips with values from 86° F to 140° F. A pack of ten (10) of these horizontal strips (item 59535K13) costs $14.49. That’s a mere $1.40 per barrel for strips — cheap insurance for your precious barrels. For best barrel life, you should try to keep your barrels under 120 degrees F.
NOTE: On the McMaster.com website, you’ll need to scroll down to the multi-use “Temperature Indicating Labels”. Then click on the horizontal label and select item 59535K13, as shown below.
Forum member Nomad47 says: “I have temperature strips (bought at McMaster-Carr) on all my barrels. I try not to shoot when the barrel gets to 122 degrees or higher[.]” Here are photos of the McMaster-Carr temp strips on Nomad47’s customized Savage.
Creedmoor Sports now offers handy Temp Strips, with 3-packs for $12.95. These have colored temp range markers so you can quickly see if your barrel is getting too hot. Creedmoor Sports notes: “The temperature range of 30-160° spaced in 10° increments fit most … shooting situations. The 1″-wide 6″-long LCD strip will provide many years of service. In general, we recommend that if a barrel begins to reach 140°, it is too hot and continuing to shoot at these temperatures accelerates barrel wear These barrel temperature strips use a 3M® adhesive and will stick to blued, parkerized and stainless barrels.”
Bad things can happen if your barrel gets too hot. First, with some barrels, the point of impact (POI) will shift or “walk” as the barrel heats up excessively. Second, even if the POI doesn’t change, the groups can open up dramatically when the barrel gets too hot. Third, if the barrel is very hot, the chamber will transfer heat to your loaded cartridge, which can lead to pressure issues. Finally, there’s considerable evidence that hot barrels wear out faster. This is a very real concern, particularly for varmint shooters who may shoot hundreds of rounds in a day. For this reason, many varminters switch among various guns, never letting a particular barrel get too hot.
 Neconos.com offers BAR-L Temp Strips that visually display heat readings from 86 to 140 degrees. Think of these strips as compact, unbreakable thermometers that monitor barrel heating.
Put a strip on the side of the barrel and the barrel’s temp will be indicated by a stripe that changes from black to green. There is also a “general purpose” strip that reads to 196 degrees (see bottom row). The Benchrest model strip (86°F to 140°F) is in the middle. These Bar-L temp strips cost $9.00 each, or $25.00 for a 3-pack.
NOTE: These strips can be permanently fixed to the barrel with the heavy-duty clear plastic tape strip provided with the BAR-L Temp strip.
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