308 barrel life and signs, for FTR

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SND

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This is quite specific to F-class/FTR shooters & competitors. When pushing 175-200+grain bullets, and trying to hit that small V, what kind of barrel life are most of you getting? and what usually tells You its done?
We know that with 155gr and a bigger target(TR) 4000-5000 rounds has been fairly common. Obviously the last few years FTR pushes things a bit harder, and target is much smaller...
I'm starting to thinking around 1200rounds is about it. Anyone else?
 
It is my understanding that throat erosion is determined primarily by the amount of powder, relative to the bore diameter.
Not sure that using a heavier bullet would make much difference.
One of the indicators that a barrel is reaching the end of the line is when there is vertical stringing at long range, this resulting from velocity variation.
 
I unscrewed the barrel from my Savage FTR last year when the groups opened up to 3/4 moa, it had around 5500 rds. through it about 1/2 of that was 185's. Still have the barrel and may get it set back and the chamber recut as that will extend its life.
 
SND said:
This is quite specific to F-class/FTR shooters & competitors. When pushing 175-200+grain bullets, and trying to hit that small V, what kind of barrel life are most of you getting? and what usually tells You its done?
We know that with 155gr and a bigger target(TR) 4000-5000 rounds has been fairly common. Obviously the last few years FTR pushes things a bit harder, and target is much smaller...
I'm starting to thinking around 1200rounds is about it. Anyone else?
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First let me say that even TR shooters demand the best from our equipment. ��To the people who regularly finish in the top of the agg, good enough is replaced with as good as it can be. One of our longest running successfull competitors suggests that after about 2000 rounds you may expect an occasional unexplainable flier at 900m. Personally I still get occasional unexplainable fliers at 900 m with a new barrel so until I can run 2000 without any fliers I'll change after 3000 or when I experience regular fliers.
 
Under 1/4 moa elevation at any distance and no random elevation fliers is what I'd like to get. I know my position ain't always great yet and I still have to tweak a few things on the set up and reloading for better consistency. I still lose too many V's, and the occasional point to elevation.
Changing many things again for next year.
 
Keep in mind that you can have the used barrel "set back"
Depending on what shooting you do and what minimum barrel length you have and need...
The gunsmith can shorten the barrel about 3 inches from the back and mount it again and then you're good for another couple thousand rounds with a little less velocity though.
 
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Modern metallurgy is far better than a generation ago and I would expect about 5000 rounds through before you start to see changes.
I haven't seen any change in group size or unexplained fliers yet with about 3500 rounds through the barrel.

JJ
 
Most of the guys i shoot with are seeing accuracy start to drop off around 2400-2600rounds when shooting the 185-215gr. Pushing then really hard and your accuracy will drop off even faster.
 
The commonly used life of the 308 in target shooting has been 3000 rounds. There are various formulas around to predict barrel life. AccurateShooter.com has an Excel spreadsheet which you can download. No idea how accurate it is, but it considers the caliber, amount of powder used, the powder heat potential, pressure, and whether or not the bullet has moly. I have the spreadsheet downloaded, and ran through some .308 assumptions for comparison. The powder used and the heat potential does have a significant effect on the life prediction. Commonly used Varget comes out at 2956 rounds, or very close to the experience derived number of 3000. However if you step up to a double base powder like N540, life goes down to 2746 rounds. And if you go to a low heat powder like N150, life jumps to 4123. 43 grains and 60,000 psi was assumed for all three cases. The other interesting thing that comes out of this spreadsheet formula is that the less powder you use, the longer the life. Or, in other words if you go up in bullet weight, life will increase as powder weight goes down. Not exactly what one would guess...
 
I have seen guys go 8000 rounds and still made the Canadian Bisley team. I believe that a barrel starts to go around 4000-4500 rounds, but there are some factors that will decrease this. One advantage that TR shooters have is that we shoot slower than F Class shooters. Shooting 3 to a target, it could be almost 3 minutes between shots. Nothing will wear out a barrel faster than shooting a lot of rounds down a hot barrel. When I was shooting a lot in the US, shooting 2 sighters and 20 rounds on score in a 22 minute time limit was hard on barrels. You might get 3000 out of a barrel if you had to shoot single string all the time.
 
OK, we all understand the accuracy bug and a 1/4 MOA is better than a 1/2 and that's of course better than a 3/4. However, one thing not mentioned here is the shooters ability to read the wind. If the best I can do is judge the wind to within +/- 2 MPH ( pretty good ), then at 900 yds when I figure it's a 10 but it changes from 8-12 MPH, I can be out by almost 3 MOA. Sure the more accurate rifle is better, far better, I get it BUT are you better spending your $$$ on improving a 3/4 MOA rifle to be a 1/2 MOA or just better learning the wind? It's worse if you have a fishtail wind from 11 o'clock to 1 o'clock because now you can be out 3-5 MOA. I'm a TR guy but I've seen F class guys go into the 3's (AND 2's) because of the wind with a VERY accurate tube. If you're already a top shooter/wind reader then get the barrel, but if you're new (ish) then far better to learn the wind. Sorry for the rant but Connaught was very windy at the Long Range AND the ORA match's this year, many men and ladies lost big points to the wind.
 
SND said:
This is quite specific to F-class/FTR shooters & competitors. When pushing 175-200+grain bullets, and trying to hit that small V, what kind of barrel life are most of you getting? and what usually tells You its done?
We know that with 155gr and a bigger target(TR) 4000-5000 rounds has been fairly common. Obviously the last few years FTR pushes things a bit harder, and target is much smaller...
I'm starting to thinking around 1200rounds is about it. Anyone else?
Click to expand...

If you want V bull accuracy for EVERY shot in dead calm air at 900m, the barrel, or more correctly, the throat will not work for long - well under 1000rds. BUT careful testing and reseting of load and OAL to keep in the best node will allow a barrel to shoot quite a long time before a set back is necessary.

Depending on the bullet bearing surface length and ogive to lands distance for best shooting, you can chase the lands quite a bit....And the amount of throat erosion is really doing to depend on the barrel steel and that is rarely the same twice.

The rest of the barrel is going to last a lot longer then the throat area so keep that in mind when you decide when to replace the barrel.

Jerry

PS.. I totally agree that matches are won and lost by wind reading skills.
 
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I definitely still have many things to work on and improve, I very well may be the problem of this random elevation thing, but was curious about what others noticed or expect out of their barrels for longevity.
I only had to move up .020" to touch the lands from new, though I had freebored it real long to start with to be between 175 and 220gr scenars, which was a compromise a bit. Should have made it about .080" shorter and not worried about 220's until the 300wm.

Oddly so far a lot of the things I try that should improve things, make them worse half the time(part of the fun I guess...). One of my best relays this year was when I dropped my open box of ammo while getting set up and they all got mixed from how I had sorted them, wiped the grass and dirt off them... then grouped 8 out of 10 in about 2" at 600m(very calm weather), but had 2 that were low 5's, dead center on wind but low. Probably bad position and/or light changes too, still trying to figure out the light thing.
 
SND said:
but had 2 that were low 5's, dead center on wind but low. Probably bad position and/or light changes too, still trying to figure out the light thing.
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My guess would be intermittent cloud cover for the low shots. Actually low means sunshine broke out.

You will hear guys say that clouds cause shade and since shade is cool, the bullets will hit lower in the cool dense air but that is not correct. Bullets wll hit high in the shade because of the direction of image shift.

It's the apparent location of the target that moves as the clouds come and go. It's a mirage thing.

Just pay attention during a match and you will see most shooters will fall for it and then speculate about the cause. Just watch the clouds and you'll predict the outcome. When the range goes to dark shade, most guys will hit high.

Watch this video to see mirage in action. The target looks like it never stops moving.

 
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