The Concept of Barrel life & Chamber Setback

[Dimner]

I have some noobie questions when it comes to what everyone here talks about in regards to 'barrel life'

From context, I am assuming that 'barrel life' in the millions of threads I have read is in regards to 'competition worthy barrel life'

More specifically, the barrel life in which one can reasonably expect the barrel to maintain the accuracy/precision level from a well tuned load when the barrel is new to the point when it will begin deteriorating. So if someone says, the barrel life of that cartridge is about 2500 rounds, the idea is that your tuned load can/could/may/probably start acting up at 2500. Sometimes it's alot sooner sometimes it is alot less. It depends on the barrel. So I think I have the correct notion of barrel life. Maybe I get a B+ on my definition if you were to grade it?

So now that we are talking the same thing about 'barrel life'.... Here is my question.

How does Barrel setback come into play? I see people talking about getting a longer barrel for their build so they can set it back a couple times.

• Are those couple set backs assumed to be within the average barrel life?
  • Meaning, if the barrel life is 2500, you may have to, depending on the barrel during the 2500 rounds, do a couple set backs?
• Or, does it mean at 2500 rounds you can expect to set the barrel back and get more usable life with an altered tune?

If I understand correctly, the barrel setback is so we can have a fresh throat that has eroded after many firings. But what about the rest of the barrel? Is it still any good? I imagine even with a barrel setback the bore is still never going to be as accurate as the new bore right?

 

[Will Henry]

Setting a barrel back, to restore accuracy, is common enough but the timing and degree of setback will vary. In some cases, a guy might set an exceptional barrel back a small amount (say, .030" or so) when accuracy has fallen off perceptively, but not greatly. This might take place when the barrel has as little as 500 shots through it. Another scenario has the setback occurring when the barrel is no longer performing and is well worn, say, 2500 rounds+. The first scenario is often very successful, the second, somewhat less so. There are variations between these two. Erosion can vary in appearance and effect, making the setback more or less effective, and sometimes, more or less of a challenge.
It has been my impression, a barrel which is chambered for what might be termed a "barrel burner" will erode much further up the bore than one chambered for a milder cartridge. When carried to extremes, we can compare a 22LR in which accuracy has fallen off because it has burned the throat right ahead of the chamber. You can set this back very successfully because the rest of the barrel is pretty well unaffected.
Meanwhile, inspection of a 22-250 in which accuracy has fallen off, might show rifling missing for a couple of inches and the barrel noticeably altered well beyond that. Setting this barrel back is likely to be a bit of a waste of time. If accuracy is restored, it may not last long. WH

 

[HTSmith]

One thing to keep in mind is that, unless you can do your own work, a gunsmith will typically charge as much for a setback as a new chamber and fitting job.

 

[gme]

a setback may help a barrel that's lost it's edge for a little while, it will not extend barrel life to that of a new barrel, personally I advise my clients against it as the cost is the same as fitting a new barrel and running a reamer in over the old throat with any deposits (especially carbon) reduces the tool life

 

[Dimner]

Okay thank you much everyone. This makes a lot of sense. I'll not worry about accounting for multiple setbacks when figuring out the barrel length for my build. I'll just go with my desired length. If it comes to the rare reason to setback once, I'll just deal with the shorter barrel.

 

[davidjoe]

If the barrel was really good at one time, I do have them set back. My recent two 1.50” tapered barrel blanks, 5R with extra length totaled $1,450. That’s really getting up there for blanks and I’ll hope they are worth a set back, when that time comes.

 

[urbanrifleman]

Try one of the UrbanRifleman barrels. They are $320. Then you can just buy another one when that one wears out, and screw it on in 5 minutes and go shooting.

Ps: recently I have had more questions on barrel life than anything. People are suddenly OBSESSED with whether they will get 2000 rounds or 2500 rounds. Even more than actual performance. I've only had a few customers actually shoot barrels to the end of their life and order a replacement. Be it because people have multiple rifles, or that they don't shoot as much as they think, I don't see people grinding through barrels like pro shooters.

 

[1K6BRA]

Barrels are like a piece of chewing gum. When it wears out, depending on acceptable taste, throw it out and get a new piece. You will be glad you did.

 

[ebb]

I once owned a 300 Jarrett chambered rifle. Accuracy had fallen off considerably and I had another barrel put on that action. Years latter I got a Hawkeye bore scope and looked in the old Jarrett barrel. It had fire cracking over 1/3rd of the way to the muzzle, I would have had to cut 9 or 10 inches off of it to get to anything close to good rifling. Like Will Henry said some may be worth it some will not. Look inside and remove all doubt before spending much time and money.

 

[Forum Boss]

Another thing to consider when seeing a decline in accuracy is wear/damage to the muzzle and crown. Recrowning the muzzle is relatively inexpensive.

Some guys harm their barrel crown with improper and/or careless cleaning techniques.

 

[Dimner]

Reason I brought this up was really for a learning experience. I wanted to understand a bit more of what people were intending to communicate in those barrel life/set back thread.

Also, the information you have all provided has really helped. I wont be duped into adding an extra 4" on my barrel just so I might end up setting it back a few times. I am not a competitor, so my real world 'barrel life' is going to be much longer than what you fine competitors would be comfortable with. In fact, I might never reach the end of the barrel life... in my lifetime!

 

[Dimner]

Another thing to consider when seeing a decline in accuracy is wear/damage to the muzzle and crown. Recrowning the muzzle is relatively inexpensive.

Some guys harm their barrel crown with improper and/or careless cleaning techniques.

That's a good point, perhaps those of us who are not competing, but looking for long lasting performance should treat re-crowning as a given through the life of the barrel. Just like normal vehicle maintenance .

 

[Will Henry]

So, I've been working on some videos , and as it happens, the first is on setting back and re-chambering a barrel. Well, while this You Tube stuff is second nature to teenage girls demonstrating lip gloss application, it's pretty tough sledding for a 75 year old guy who can barely write an e-mail. I'm sure I've made, and discarded, at least a dozen videos. It is plain, while I may have some gunsmithing knowledge, as a videographer, I have a way to go. Anyway, sometime within the next week or so I should have something up on this subject. WH

 

[Murray Brook]

@Dimner
Something that might interest you

Barrel Life Calculator – Pierre van der Walt on Cartridges, Rifles & Hunting

pierrevanderwalt.com

 

[Capt. Oblivious]

With bigger 6mms we generally set them back around 900/1000s rounds just before the fire cracking really sets in and then run them another 1200 or so, some go longer some don't. When/If you do a setback let your GS cut off a inch or so at the crown end as well and redo the crown.

I have ran 6mm barrels without setting them back till they just stop shooting at longer ranges and I have also had them set back around 1500 rounds and im really not sure that you gain allot of "barrel" life by setting the barrel back you might just have a little better accuracy a little longer.

I saw a Dasher and XC come back to life after a setback close to the end of the barrels life and they were hammering again afterwards but they "died" really quickly after that, I believe the barrel would have stopped shooting at the same point the shooters just got a couple 100 more very accurate shots compared to a couple 100 avg accurate shots out the barrels. The current barrel on my belly benchrest 6mm gun is probably going to be shot till it stops shooting without a setback.

 

[urbanrifleman]

If you want prolong your barrel life buy a box of Tubb tms bullets and shoot 2 every 200 rounds. They smooth down the firecracking. Works like a charm.

 

[LVLAaron]

They smooth down the throat, too.


For the competition rifles that see a lot of rounds, I find setting them back "a thread" and refreshing the crown is a quick job and really brings the barrel back to life.

 

[urbanrifleman]

They smooth down the throat, too.


For the competition rifles that see a lot of rounds, I find setting them back "a thread" and refreshing the crown is a quick job and really brings the barrel back to life.

Firecracking in the throat. Yes. The idea is to smooth the jagged edges of firecracking that tears the bullet jacket and leads to copper atomizing in the downstream part of the barrel.

The reason barrels stop shooting is mostly due to the barrel tearing the jackets. Turning good bullets into bad ones.

 

[LVLAaron]

And because the throat erodes, which abrasives of any kind accelerate.

 

[urbanrifleman]

And because the throat erodes, which abrasives of any kind accelerate.

Have you actually tried the TMS bullets, or are you speaking theorectically?