Throat erosion and barrel life...


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Surefire
July 9, 2006, 12:32 AM
Which cartridges are the worst at barrel life and throat erosion (e.g. shortest barrel life)?

Which are the best (e.g. longest barrel life)?


Where do the most common and popular cartridges fit in in these extremes?


Is it true that barrel heat (shooting too quickly) accelerates throat erosion?

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Ol` Joe
July 9, 2006, 01:42 AM
High pressure large capacity for their bore cartridges are the hardest on throats. The Ultra mags, rounds such as the 257/270 Wtby for example.

The best barrel life will likely come from rounds like the 45-70, 22 LR, 30-30.

Most COMMON cartridges seem to fall anywhere in the list. They run from high pressure cartridges large powder to bore capacity (22-250) to the low pressure rounds (30-30)

Shooting fast and over heating the barrel is the fastest way to erode the throat, no matter what cartridge you are fireing.

buttrap
July 9, 2006, 06:45 AM
Also depends on the gun and barrel design too. A chrome lined bore with a high speed round will tend to take much more rounds than some guns with soft steels in the barrel with jacketed bullets. Its a pretty wide issue with a lot of variables that come into the situation.

USSR
July 9, 2006, 08:02 AM
Which cartridges are the worst at barrel life and throat erosion (e.g. shortest barrel life)?

While there are others, here are some of the more common ones: .220 Swift, .22-250 Rem., .243 Win., .25/06 Rem., 6.5-06, 6.5-.284, and most of the magnum cartridges.

Which are the best (e.g. longest barrel life)?

Where do the most common and popular cartridges fit in in these extremes?


Most cartridges are good, especially if velocities are kept below 3,000fps.

Is it true that barrel heat (shooting too quickly) accelerates throat erosion?

Definately true.

Don

Thin Black Line
July 9, 2006, 08:03 AM
Shooting fast and over heating the barrel is the fastest way to erode the throat, no matter what cartridge you are fireing.

+1. When shooting precision bolt action, I *always* let the barrel cool
long enough between shots so it is tolerable to touch by my sensitive little
fingers at midpoint on top of the barrel. Depending on weather conditions,
this can mean waiting a couple minutes or more between shots once things
are underway. You will notice your point of impact change between a
hot, warm, and cold barrel which increases the size of your groups. If
you shoot with a barrel at a consistent temperature (controling for ammo),
it will show the MOA capabilities of your rifle more fairly rather than a
change across wide temperatures.

Yes, the chrome-lined barrels on mil weapons will take much more heat, but
the accuracy still goes to crap the hotter it gets (just like any other hot
barrel).

Thin Black Line
July 9, 2006, 08:08 AM
Forget to mention I get a barrel life of over 10K with a bolt action using the
touch method. Sold two that were still doing sub-moa. Not much noticable
change with mil rifles at 4k and accuracy still tolerable at 6k.....just don't
get them hot enough to brand cattle.

Surefire
July 9, 2006, 12:36 PM
Looks like I will plan to shoot the bolt actions slow (using the touch the barrel method). One of the rounds I recently bought was in the quick to erode list.

It looks like military style semi-autos (M1A) maybe can take a little more shooting quickly... I'll look into picking something like this up as well.

rangerruck
July 9, 2006, 02:35 PM
ol joe is very right, any cartridge that is considered 'overbore' will burn up the throat faster. the 30.06 and the 308 are actually quite good, even the old 35 remmy and the 358. the 243 is actually quite bad, because of it's erratic high pressure spikes. One of the best, for a game round is the old 6 mm remmy. excellent volume/cubic space for burning in side the shell, with an extra long neck. the long neck dissapates the heat, and gives the propellant plug a little more space to burn up in, before this "coal" makes it out into your throat...
what are also very good are the wsm and wssm's. Case has huge cubic volume inside for burning and expanding while using usually a little less powder.

SRMohawk
July 10, 2006, 02:59 AM
While there are others, here are some of the more common ones: .220 Swift, .22-250 Rem., .243 Win., .25/06 Rem., 6.5-06, 6.5-.284, and most of the magnum cartridges.
Gees Don (USSR), now did you have to go and say all that? Hell, I might as well just go and throw all my rifles into the sea! :banghead:

Seriously though fellas, I know some (if not all) of you think I must be a regular half-wit given the questions and problems I post at this forum. But I was actually a student of precision rifle for several years before I started having expensive, custom rigs built for myself. And in all the years I've been into it, I still find that there are at least several things about the metallic cartridge and bolt rifle interface that elude our understanding. For example, there is no way to evaluate and/or measure this, but almost any major barrel maker will admit that barrel harmonics have more to do with accuracy, velocity, and even barrel life than anything! And that just because a barrel -- insofar as we have the technology to evaluate it -- appears perfect, there's still no guarantee it will shoot. Barrel harmonics are also believed to change under severe stress, as with the above enumerated cartridges, necessitating radical change in the combinations that yield exceptional accuracy. And this happens notwithstanding the obvious physical deterrents thereof (e.g. our subject throat erosion and/or throat 'roughening'.

USSR
July 10, 2006, 08:57 AM
Gees Don (USSR), now did you have to go and say all that? Hell, I might as well just go and throw all my rifles into the sea!

Sorry 'bout that SRMohawk.:D You did bring up a good point about the barrel make being a factor, though. While most of the barrel makers use pretty much the same steel, some methods of rifling will help a barrels life somewhat. Cut rifled barrels will generally last a bit longer than barrels rifled by other methods, and in particular, Boot's barrels with their high lands are noted for their long life. Another factor in barrel life is the type of powder used. Double based powders, while providing for higher velocities, tend to reduce barrel life somewhat. But generally, any cartridge with a lot of powder in relation to it's bore size, is going to take it's toll on the throat.

Don

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