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Joined: Sep 2008
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Campfire Tracker
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OP
Campfire Tracker
Joined: Sep 2008
Posts: 5,702 |
When reading about various cartridges I sometimes see comments like " With the lighter bullets in the XYZ you can get fantastic high velocity but barrel life plummets and throat erosion will show after a small number of rounds"
XYZ= fill in the blank, 220Swift,264Win,7mmSTW etc....
So the Question is, Is it "Velocity" that washes out the throat? or is it the "Heat" from all that powder going down a little bore that is to blame?
It's the New Year and I'm working on my Loonie Card Renewal.
"Camping places fix themselves in your mind as if you had spent long periods of your life in them. You will remember a curve of your wagon track in the grass of the plain like the features of a friend." Isak Dinesen
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Joined: May 2005
Posts: 7,046
Campfire Tracker
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Campfire Tracker
Joined: May 2005
Posts: 7,046 |
Lighter bullets equal higher velocities Higher velocites burn larger charges of powder Larger charges of powder increase both heat and physical erosion and blasting effect on the lands. Slower burning powders sustain the heat.
If you spread the shots, the barrel will last several lifetimes even on a .257 Weatherby.
If you range shoot, it will be done in 800-1,000 rounds no matter what bullet weight and powder charge.
JW
When truth is ignored, it does not change an untruth from remaining a lie.
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Joined: Jan 2002
Posts: 12,784
Campfire Outfitter
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Campfire Outfitter
Joined: Jan 2002
Posts: 12,784 |
The way I understand it is that light bullets generally can't be seated close to the lands. In that case, as the bullet moves into the throat, gas bypasses the bullet, before it has a chance to obdurate, and it is this "gas cutting" that creates higher than normal wear. HTH, Dutch.
Sic Semper Tyrannis
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Joined: Oct 2003
Posts: 411
Campfire Member
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Campfire Member
Joined: Oct 2003
Posts: 411 |
Why is throat erosion detrimental to accuracy since it is near the chamber? If your rifling is good past the first few inches of barrel and your muzzle is in good shape, is it still going to cause you problems?
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Joined: May 2004
Posts: 55,889
Campfire Kahuna
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Campfire Kahuna
Joined: May 2004
Posts: 55,889 |
DW...Bullets are supposed to be sorta smooth and enter the bore straight. Eroded throats sorta screw all that theory up. There's other stuff going one as well but I don't have time to write it up. Look at it this way...you want a fresh young thing to sport with or a worn out hooker?
I am..........disturbed.
Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain
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Joined: Aug 2002
Posts: 14,440
Campfire Outfitter
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Campfire Outfitter
Joined: Aug 2002
Posts: 14,440 |
I've been pondering this for some time.
Which barrel throat will last longer between these two cartridges shooting the same bullet, a 140 VLD, at the same speed, 2,850 mv.
Barrel lengths being equal.
A 260 Rem shooting a stout MAX load of 46 grains of slower burning powder for 65,000 psi.
OR
A 6.5-284 shooting a slightly reduced load of 56 grains of slower burning powder for 50,000 psi.
15,000 psi difference between the two but 10 grains more powder.
Will the lower psi reduce throat wear or will the extra 10 grains of powder cause more throat wear?
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Joined: Mar 2005
Posts: 5,586
Campfire Tracker
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Campfire Tracker
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Weren't the Howell cartridges designed for high velocity AND longer barrel life by using more powder at lower pressure?
Bruce
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Joined: Aug 2002
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Campfire Outfitter
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Campfire Outfitter
Joined: Aug 2002
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Weren't the Howell cartridges designed for high velocity AND longer barrel life by using more powder at lower pressure?
Bruce
That's my understanding.
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