What determines barrel life?

Defusion

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Oct 15, 2008
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I have ordered myself a .308 AI AE, but already considering the future of the rifle. In the future I might want to shoot .260 or other 6,5mm cartridge.
Generally speaking, 6,5mm calibers have a higher muzzle velocity, and shorter barrel life. 6mm even more so.

My question being, barrel quality being equal, is velocity the only thing that causes the 6,5 and 6mm barrels to wear out faster?
Would it be possible to load for lower muzzle velocities, equal to .308, and have the same barrel life as it has? The main reason behind this is that most of my training would be done at 100-300m, and I could save the hotter loads when shooting long range.
 
Re: What determines barrel life?

Heat burns throats away. That comes from the combined effects of power burn temperture, volume of the gas, gas pressure, barrel alloy, time between shots, etc. Bullet velocity, as such, isn't a major issue.
 
Re: What determines barrel life?

^^^
This.

It's a function of how much powder is burned- and how fast- in relationship to the diameter of the bore.

Keep in mind, a hunter's opinion of when a barrel is "shot out" (acceptable accuracy) can be FAR different that that of a benchrest or long-range shooter.

Lots of hunters would gladly take 1,500 round "shot out" barrels from a .300 WM long range target rifle, still shooting minute of angle for their hunting rifle...
 
Re: What determines barrel life?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigBore56</div><div class="ubbcode-body">attherange...hit it perfectly..3000+ fps is the magic number that takes it's toll on barrels if you want the easy answer. </div></div>

I'd say it's 3000+ fps with heavy-for-caliber bullets.

A 223 will live a long life with 40gr pills at 3200fps.
 
Re: What determines barrel life?

Hello Defusion,

First off, let me say this; not all barrel qualities are the same by no means. When a shooter wishes to purchase a new long range rifle, he or she needs to ask themselves a few questions before diving in and spending all that money on a purchase;

1.)- What will be the main use of this new rifle?
2.)- What caliber would best suit my needs?
3.)- What kind of profile and or taper would I like to have for my new barrel?
4.)- What weight of bullets am I thinking about shooting and reloading?
5.)- Am I going to mostly shoot short distance (out to 300 to 500 yards) or am I going to got for extreme long range (1,000 to 1760 yards and beyond)?

These are all very important questions that you need to ask yourself. I currently have two sniper rifle platforms that are chambered in 6.5 Creedmoor and they both shoot my 139 gr. Lapua Scenar HPBT handloads beautifully. The Lapua Scenars provide the shooter with a great long range bullet that boasts a G1 ballistic coefficient of 0.615 which is absolutely incredible for the size of the bullet that it is. I have used both of my 6.5 Creedmoor rifles in several long-range competetive shoots and I kept up with the big magnums with no problems as long as the wind wasn't pushing more than 8 to 9 mph with anything greater than half value.

Finally, let me tell you about how to get the most out of the barrel life of your rifle; when you go out to the range and shoot, say anything from 50 to 100 rounds, after you shoot, clean your barrel with a good solvent. I found both Hoppes #9 and Shooters Choice works very well. I also frequently use JB non-embedding compound in my barrel as well. Just make sure to use the non-embedding kind and nothing else.

I purchased my first of several Sako TRG-42 rifles about 8 years ago, chambered in .338 Lapua Magnum. The barrel was rated to be able to shoot about 2200 rounds before it would be time to replace it. I managed to squeeze out right at 3300 rounds before I lost my accuracy node. At that point, I had no other choice than to replace the barrel. Even the gunsmith couldn't believe that I made it last that long. It's all very possible to make a barrel last. It all depends on how the shooter takes care of the barrel and perfoms preventative maintenance as well as not over-heating the barrel with a ton of consecutive shots, over and over. Overheating can lead to barrel warping very easily.

I run both of my 6.5 Creedmoor rifles between 2700 to 2800 fps with no problems. Remember; yeah, faster muzzle velocity is great, but don't forget about the G1 ballistic coefficient. You need to find the sweet spot that's between the two. You can very easily shoot your rifle with moderately faster speeds, but don't over-clock them and definitely watch for over-pressurization signs. Excessive muzzle velocity leads to more rapid heat in the barrel as well as running the risk of over-pressurizing, which in turn, leads to a much shorter barrel life.

Well, anyway, I hope that this may have helped you with your questions about barrel life and such. Just be safe, shoot straight, and have fun.

Keep your powder dry, Defusion. Until next time.


Sakoshooter...
 
Re: What determines barrel life?

It is a combination of several factors but the biggest two IMHO are bore size (caliber) to powder charge (how much fuel is being burned) and the time between shots. Other factors are bearing surface length and bullet weight. They all create heat and pressure, heat and pressure kills barrels. Shoot a long bearing surface heavy for caliber bullet in a high powder charge to bore size ratio cartridge and you have the recipe for shorter barrel life. Shooting this combo with little time between shots will compound the issue.

But they are fun and more forgiving in the wind. No free lunch in this game. I started out with a 308 and a 223, then I got a 243 and could not believe how much easier it was to connect down range at distance. I am kind of happy I took this path as I got most of long strings/high volume of fire out of my system on the first two so now when I shoot my 243 I don’t feel the need for fast follow ups that go on and on and on and on… doesn’t mean I don’t want to but I can resist the temptation easier now.
 
Re: What determines barrel life?

A simple test you can do at home,

Eat LARGE plate of hot curry, wait approx 1hr,
Sit on toilet and push like hell.
Measure burn rate.

Repeat test with SMALL plate of hot curry,
Compare burn times.

(Do NOT try for 3000fps for purposes of this test)

this will give you an 'approximation' of the relationship between case capacity and throat erosion, for similar sized ringpiece. Sorry.. Calibre.
 
Re: What determines barrel life?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gfunkUK</div><div class="ubbcode-body">A simple test you can do at home,

Eat LARGE plate of hot curry, wait approx 1hr,
Sit on toilet and push like hell.
Measure burn rate.

Repeat test with SMALL plate of hot curry,
Compare burn times.

(Do NOT try for 3000fps for purposes of this test)

this will give you an 'approximation' of the relationship between case capacity and throat erosion, for similar sized ringpiece. Sorry.. Calibre.
</div></div>
LOL! But now how do I test this with differently sized ringpieces
wink.gif


Thanks everyone for the input.
I will try to read and understand the highly scientific PDF posted by Temp9. A quick scroll already showed some of the key factors.
 
Re: What determines barrel life?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">

LOL! But now how do I test this with differently sized ringpieces

</div></div>

wife and kids <span style="font-style: italic">of course..</span>
laugh.gif
 
Re: What determines barrel life?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">Heat burns throats away. That comes from the combined effects of power burn temperture, volume of the gas, gas pressure, barrel alloy, time between shots, etc. Bullet velocity, as such, isn't a major issue. </div></div>

I would say it like this:: Barrel life is inversely related to the amount of time the burning charge remains in the plasma state.

While in the plasma state, the iron atoms in the barrel are subject of becoming part of the plasma (gas) and eroding away. (Iron goes gaseous before the chrominum and nickle.)

Small bore guns with high velocities have a longer plasma residence time.
 
Re: What determines barrel life?

Bart Bobbitt, who posts at The Firing Line and at Long Range hunting [I have been following his posting habits for 20 years] has a formula for barrel life.
http://thefiringline.com/forums/
http://www.longrangehunting.com/forums/

His formula for a worn out barrel is for him at the national level of competition [a higher standard than mine]. The NRA icon for accuracy is a painting based on a photo of Bart at camp Perry.

The formula can be seen on yarchive on the WWW.
http://yarchive.net/gun/barrel/barrel_life.html

This info pre dates gun forums on the www, it is from the old usenet forum rec.guns, that some of us posted on in the 1990s.

I can see it for free via signing up through Google
https://groups.google.com/forum/?hl=en&fromgroups=#!topic/rec.guns/iC-CoKQCeW8
 
Re: What determines barrel life?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigBore56</div><div class="ubbcode-body">attherange...hit it perfectly..3000+ fps is the magic number that takes it's toll on barrels if you want the easy answer. </div></div>

I'd say it's 3000+ fps with heavy-for-caliber bullets.

A 223 will live a long life with 40gr pills at 3200fps. </div></div>
This is my understanding i.e. combination of heavy bullets and high muzzel velocity.