Barrel length questions

dawgmaster

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I’ve got a 260 Ackley, 8 twist, 28” length, shoot 139-142 bullets. Typically getting about 2950 FPS velocity.

If I was to cut 4” off.....making it a 24” length....

1) How much velocity do I possibly lose?
2) Does it increase throat erosion due to unburnt powder?
3) Does it potentially stand to be less accurate? And if so, mainly just at long range or short as well?
 
I can answer 1 and 3, from cutting and testing a 24 inch .308 down to 19.
And recording velocity loss with a magneto speed chrony

You’ll lose about 17 -25 ffs per inch.
It varies per inch.
So you will loose appropriately 70 to 90 FPS, for 4 inches of barrel.

As for accuracy, I’ve read , a shorter barrel should have better accuracy,due to less barrel whip.

However, I couldn’t tell the difference, between 19 and 24
 
2) Barrel length is unrelated to throat erosion.

3) If you lost 100fps, at 1000m, 10mph wind at 90 degrees, you'd need an additional half minute of correction. Grouping ability shouldn't be affected, assuming proper crown.
 
So far then, it sounds like I only stand to lose about 100 FPS which will still have plenty of gas for 1000 yards and accuracy should continue to be good?? So is there any issues with unburnt powder?
 
I cant possibly conceive that cutting the barrel will have any effect on throat erosion? What makes you think it does?

I was just under the impression that with some calibers it was preferred to have a longer barrel so as all the powder was burnt more cleanly??? Maybe I’m misinformed but I thought if it wasnt burnt properly then that increase erosion?? So if I’m mistaken then I guess that’s good to hear that it won’t??
 
Thanks for all the info! Last couple questions....
If the round count on the barrel is 2000(still shoots great) and getting near the end....
Should I go the cheaper route and just cut 4” off at the muzzle and recrown?? Or am I better to take the 4” or at least what is available at the chamber end and cut and rechamber? Would 3-4” get into enough fresher rifling to make the extra expense worth the while??
 
If it were my rifle, with 2000 rds of .260AI through it, I would shorten it from the breech.
Then again, I do my own smithing, so cost is not an issue.
 
It would be much cheaper to cut and recrown.
I did one last year ,11 degree target Crown, it took about an 1/2 hr.

Once you get into ,to much cost, you may as well buy a new barrel, exactly as you want it.
 
I was just under the impression that with some calibers it was preferred to have a longer barrel so as all the powder was burnt more cleanly??? Maybe I’m misinformed but I thought if it wasnt burnt properly then that increase erosion?? So if I’m mistaken then I guess that’s good to hear that it won’t??

Burning powder on its own does not cause erosion. Heat and friction causes erosion.

In theory, shortening the barrel and keeping all other variables equal will reduce throat erosion (I suspect by a virtually immeasurable and insignificant degree) because the bullet will exit the barrel sooner, and therefore reduce the amount of time that the barrel is exposed to hot burning gas.

As a handloader, things are rarely equal. Shortening the barrel may in fact result in unburnt powder being thrown out the end of the barrel (further reducing the peak barrel temperature and bullet velocity, further reducing throat erosion, but again by an insignificant amount). What many shooters will do when they shorten barrels, or observe unburnt powder, is they will compensate by switching to a faster burning powder. Also, when shortening a barrel, many shooters will attempt to compensate for the velocity loss of the shorter barrel with a hotter load. Hotter load and faster burning powder will SIGNIFICANTLY increase throat erosion. Trying to push a short barrel to do what longer barrels are inherently capable of is a great way to significantly reduce your barrel life.

Thanks for all the info! Last couple questions....
If the round count on the barrel is 2000(still shoots great) and getting near the end....
Should I go the cheaper route and just cut 4” off at the muzzle and recrown?? Or am I better to take the 4” or at least what is available at the chamber end and cut and rechamber? Would 3-4” get into enough fresher rifling to make the extra expense worth the while??

This is a tough call. First, I am not sure you should even be considering chopping the barrel at the muzzle. It won't be more accurate. The velocity loss will result in greater wind deflection, and could result in an insufficiently stabilized bullet. Poor workmanship can ruin the barrel entirely. The weight savings will be negligible, but will increase felt recoil.
What benefit exactly do you expect to realize with a shorter barrel?

I have never once heard a long range shooter complain their barrel was too long. Ive heard many complain about the opposite. A while back remington came out with a speciall R700 SPS Tactical with 20" barrel. Police snipers were interested because they never shoot past 200M. Many tactical minded sport shorters bought them, and most of them are for sale on the EE right now because so many people were disappointed with the velocities and poor performance at longer rangers...

How do you know 2k is close to the end for this barrel?
If you believe that its close to the end, then I suspect you should strongly consider cutting off the chamber side and rechambering. 4"? The general rule of them I have been told to evaluate how much to take off of the chamber side is to inspect for throat erosion, and cut the length of the erosion +1/2". So if you observe fire cracking and heat damage for 1-1/2" of throat into the rifling, then cut 1-1/2" + 1/2" = 2 inches of chamber and rethread/rechamber.
 
Burning powder on its own does not cause erosion. Heat and friction causes erosion.

In theory, shortening the barrel and keeping all other variables equal will reduce throat erosion (I suspect by a virtually immeasurable and insignificant degree) because the bullet will exit the barrel sooner, and therefore reduce the amount of time that the barrel is exposed to hot burning gas.

As a handloader, things are rarely equal. Shortening the barrel may in fact result in unburnt powder being thrown out the end of the barrel (further reducing the peak barrel temperature and bullet velocity, further reducing throat erosion, but again by an insignificant amount). What many shooters will do when they shorten barrels, or observe unburnt powder, is they will compensate by switching to a faster burning powder. Also, when shortening a barrel, many shooters will attempt to compensate for the velocity loss of the shorter barrel with a hotter load. Hotter load and faster burning powder will SIGNIFICANTLY increase throat erosion. Trying to push a short barrel to do what longer barrels are inherently capable of is a great way to significantly reduce your barrel life.



This is a tough call. First, I am not sure you should even be considering chopping the barrel at the muzzle. It won't be more accurate. The velocity loss will result in greater wind deflection, and could result in an insufficiently stabilized bullet. Poor workmanship can ruin the barrel entirely. The weight savings will be negligible, but will increase felt recoil.
What benefit exactly do you expect to realize with a shorter barrel?

I have never once heard a long range shooter complain their barrel was too long. Ive heard many complain about the opposite. A while back remington came out with a speciall R700 SPS Tactical with 20" barrel. Police snipers were interested because they never shoot past 200M. Many tactical minded sport shorters bought them, and most of them are for sale on the EE right now because so many people were disappointed with the velocities and poor performance at longer rangers...

How do you know 2k is close to the end for this barrel?
If you believe that its close to the end, then I suspect you should strongly consider cutting off the chamber side and rechambering. 4"? The general rule of them I have been told to evaluate how much to take off of the chamber side is to inspect for throat erosion, and cut the length of the erosion +1/2". So if you observe fire cracking and heat damage for 1-1/2" of throat into the rifling, then cut 1-1/2" + 1/2" = 2 inches of chamber and rethread/rechamber.
Thanks for the info....not really sure 2000 rounds is near it’s end??? If I shot hot 260AI loads it likely would be?? But I don’t have to push it hard at all for 1K, so I feel it likely has 3000+ rounds in it! My smith thought much the same as you and figured just 1 1/2-2” off the chamber end. My only reason for taking 4” off was that hauling 28” and about 18lbs around for coyotes isn’t always so convenient!!
 
Thanks for the info....not really sure 2000 rounds is near it’s end??? If I shot hot 260AI loads it likely would be?? But I don’t have to push it hard at all for 1K, so I feel it likely has 3000+ rounds in it! My smith thought much the same as you and figured just 1 1/2-2” off the chamber end. My only reason for taking 4” off was that hauling 28” and about 18lbs around for coyotes isn’t always so convenient!!

Guns are like hammers. They come in many different shapes and sizes, for many different applications.

No an 18 lb gun isn't convenient for coyote hunting, unless you are hunting at 1000 meters from the prone position.

Are you contemplating butchering your 1000 yard gun so you can zap a few yotes at sub 200m distances? Do you still need the gun for distance shooting?

Sounds to me like you need a second gun.
 
Guns are like hammers. They come in many different shapes and sizes, for many different applications.

No an 18 lb gun isn't convenient for coyote hunting, unless you are hunting at 1000 meters from the prone position.

Are you contemplating butchering your 1000 yard gun so you can zap a few yotes at sub 200m distances? Do you still need the gun for distance shooting?

Sounds to me like you need a second gun.

You’re pretty much right on with all the above, perhaps a second rifle is a better fix??
 
Cutting 4" off is going to make it a bit shorter, but not much lighter.
If you want a hunting rifle, getting a hunting rifle would make sense.
 
Cutting 4" off is going to make it a bit shorter, but not much lighter.
If you want a hunting rifle, getting a hunting rifle would make sense.
I have to agree, get another gun:)

I did this as a fun project, using Savage 10 TR.
I found that chopping off five inches didn’t really make much difference in the feel of it, regards to weight.
 
Burning powder on its own does not cause erosion. Heat and friction causes erosion.

In theory, shortening the barrel and keeping all other variables equal will reduce throat erosion (I suspect by a virtually immeasurable and insignificant degree) because the bullet will exit the barrel sooner, and therefore reduce the amount of time that the barrel is exposed to hot burning gas.

So... There is one scenario where it could affect throat erosion.

If a projectile exits sooner (shorter barrel) than there is less pressure duration inside the chamber/barrel where burnt/burning explosives are present.

If there is more "unburnt particles" present than with a longer barrel, and more erosion caused with projectiles moving across unburnt powder against the throat/bore than they may have more of an erosion effect, in contrast to a longer barreled bore. As you say "Heat and friction causes erosion".

Now, this is both splitting hairs and speculative, but it is also perhaps part an origin of the line of thought that shorter barrels may show wear quicker, I doubt anyone has done research but maybe you'll find something if you want to prove me right or wrong.

Here's a short but good read, which kind of counters my thought:
http://www.mssblog.com/2016/08/12/factors-in-barrel-life/
 
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Well it’s a bit of a chore to lug around, but two coyotes fell to it today....635 yards and 520 yards.....so I guess I’ll just have to cope!

So here is my new question, if I bought a tikka t3, or Savage Model 12 or maybe a Ruger American Predator etc....in 260 or 6.5CM....would they fair pretty well and successfully VS my semi custom 700 in 260AI out to 1000??? Or will I be disappointed and just end up going back to the heavy rig??
 
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