Barrel Life?

[TrxR]

Is it true that a faster twist barrel will have a shorter life span than a slower twist barrel ?

Thanks

 

[JRS]

No.

 

[Steve Blair]

No.

[br]
<sarcasm> How can you say that? I had a 6.5-284 with an 8" twist that burned out in 800 rounds. My .222 with a 14" twist has over 4000 rounds and still shoots great. : </sarcasm>

 

[Broncazonk]

Excellent Question

I hope the experienced shooters on this list, and this list has a battalion of incredibly experienced guys, will weigh in and address this question based on their experience and insight.

Bronc

 

[Steve Blair]

JRS is correct, there is no substantive difference due to twist rate. Barrel life is about heat.

 

[JRS]

Thanks Steve

 

[Nomad47]

But there will be more pressure in the faster twist (all other things being equal), so the load must be reduced to compensate.
Heat goes up with pressure, so if the pressures are equal between the two twists, barrel life should be the same since heat should be the same.

 

[Steve Blair]

Look, even if the barrel life was half with a fast twist; are you going to shoot caliber .30, 118 grain bullets at 1000 yards because you can use a 17" twist? It is the price of admission. If you want to shoot long, heavy, high B.C. bullets, you must use faster twists. [br]
Just leave your wallet with the clerk. He will see that the action, barrel, stock and sight makers, along with the gunsmith, get their share. If there is anything left over, it will be applied to match fees. That is assuming that your wife or significant other allows you to carry money.

 

[Nomad47]

Totally agree, Steve, although I don't compete. That is why all my 6mm barrels are 8 twist and my 7mm barrel is a 9 twist. Like you and others have said - barrels are an expendable item and when they wear out (and they will), I will buy more.

But to put it differently to try to answer the OP's question. . . . If you shoot the same exact load in two different twist barrels, I think the faster twist will wear out just a smidgeon faster than the slower twist.

Dang, I must be bored to want to get into this kind of discussion. It needs to warm up and the wind needs to die down a little so I can get back to my load development here in AZ.

 

[Broncazonk]

So the expert mindframe is quite simply: Barrels wear out. They come and they go. They are a part no different than brass. Treat them well, but don't get attached to them.

So the question is: Do people have/keep fond memories of one particular barrel or another over all the other barrels that have come and gone?

Bronc

 

[jonbearman]

You are right as when my hummer barrels start to loose accuracy they get retired to the scrap pile.If you shoot and wait 5 minutes between shots ,it should last a long time.If you rapid fire it,you will wear it out in no time and have to cut the barrel down for a rechamber to get more life out of it.It all depends on how fast or slow you fire to keep the tube from frying eggs.

 

[Lapua40X]

So the question is: Do people have/keep fond memories of one particular barrel or another over all the other barrels that have come and gone?

Thanks for the lift in spirit, Bronc. Your comment reminded me of a great old friend who has a collection of old barrels he's worn out over the many years (seventy of 'em) he's been shooting. They're stacked on a rack in his reloading room. He has a story to tell about every one of them.

 

[Lapua40X]

So the question is: Do people have/keep fond memories of one particular barrel or another over all the other barrels that have come and gone?

Thanks for the lift in spirit, Bronc. Your comment reminded me of a great old friend who has a collection of old barrels he's worn out over the many years (seventy of 'em) he's been shooting. They're stacked on a rack in his reloading room. He has a story to tell about every one of them and even though he's in his mid 80's and can't get down to a prone position, he's still a challenge in bench rest competition.

 

[BigDMT]

It's simple. You have to have a certain twist in whichever caliber to shoot whichever high bc bullet you want. If you find that barrel life is not as long as you would like with whatever twist rate you are using, might want to re-work a load and throttle the speed down. So basically it is what it is. The other option for longer barrel life is to just lie about it

But Idont see how a small difference of say a 1 in 8 vs a 1 in 9 in a like sized bore can have any significant difference in barrel life. That's less than a half a twist difference between those two twist rates in a 30" barrel. Actual math comes out to 0.42 twist difference in 30"

I totally agree with others that rate of fire when shooting groups probably has the greatest effect on barrel life.

 

[KevinThomas]

TrxR,

Well, technically, yes, but probably not for the reasons that you're thinking. Given the same chambering, I would expect a fast twist barrel to be the first to go, but not because of the twist itself, but what you're shooting through it. You go with a faster twist to allow the use of longer, heavier bullets. THAT'S what washes out the barrels; the heavier bullet weights. If I do up two 308s, one with a 1x14" barrel and the other with a 1x8", the 1x14" won't see any bullets heavier than about a 168, because that's all it's going to reliably stabilize. In the 1x8", I'm probably going to be running a steady diet of 210s, or something like that. It's the heavier bullet that does the damage (as sleepygator mentioned) since it takes longer to get the greater mass of these bullets moving down the bore. All that extra time, the high pressures and heat of the burning propellent is confined in the throat area, doing its dirty work. The lighter bullet moves off the seat faster, and gives those gasses less time to do damage in that area. Take a look at a shot out barrel, and that's the first thing you'll see through a borescope; 85% of the barrel looks like it's brand new, not a bit of damage, while that last 15% or so, just ahead of the case mouth and leade, looks like badly cracked asphalt that desperately needs repaving. You just see this damage quicker when heavy bullets are being used.

I should note that this applies even when using the "same" powder. Say, IMR4895 in the 168 loads, and IMR4350 in the 210 loads. Same chemical make up, same amount of energy per grain, same flame temps generated for both, but the barrel used with the heavier bullets will show significantly more wear and flame damage.

 

[Nomad47]

While that is true, Kevin, picture this extreme. . . . Take a 1:2 twist barrel and a 1:30 twist barrel. Shoot the same identical load in both. Do you think the pressure therefore the heat will be the same in both?

 

[KevinThomas]

Given the same bullet weight and charge, yes, no difference at all. Rotational forces that go into engraving and spinning a bullet within the bore really don't amount to much more than about one half of one percent. Not even a factor in most interior ballistics programs or equations used for predicting pressure.

Think of it this way; the original pitch in the M16 rifle was 1x14", which was subsequently changed to a 1x12" for the M16A1 series. The standard 55 grain M193 load for these rifles was pretty warm stuff; 3250 fps out of a 20" barrel. When the rifles were upgraded to the A4 series, the twist was tightened to 1x7", effectively double what the original rifles had. And yet, that same hotly loaded M193 continues to be used for training purposes, with no problems related to pressures caused by the doubling of the twist rate. Just not that much of a factor, so long as we're strictly speaking of the twist alone, and assuming the same aspect ratio, bore and groove diameter, and so on.

 

[TrxR]

Ok thanks for the explanations. So If I was to build a .308 with a 1in10 30" barrel and say shot 155's through it it would no worse than a 1in12 with 155's but where I plan on running 185's through it , it would lessen the life because of the heavier bullets not the different twist rate. It don't really mater as I plan to run 185's anyways but how much harder are they on the barrel than the 155's? Also would the 1 in 10 be a good choice for the Berger 185's and 185 hybrids?

Thanks

 

[BigDMT]

While that is true, Kevin, picture this extreme. . . . Take a 1:2 twist barrel and a 1:30 twist barrel. Shoot the same identical load in both. Do you think the pressure therefore the heat will be the same in both?

Well no, but that's not realistic at all.

 

[Hombre0321]

Barrels do get used up. So I figured I would find a use for those old shot out tubes. I build two or three Hot Rods every year to help fund my shooting, so I found a great use for old barrels. Radius rods, these barrels polish up real good and save me from having to make and then have them chromed.

Roland