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Joined: Jan 2010
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Campfire Tracker
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Campfire Tracker
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Yes but it has that dreaded, confusing belt 
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Joined: Mar 2006
Posts: 14,507
Campfire Outfitter
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Campfire Outfitter
Joined: Mar 2006
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IIRC George won a pretty big comp shooting one with a round count over 4000.
That's competition accuracy at a very high round count and a single set back. Shooting informally and hunting, guessing 1 barrel is all a guy would ever need. He told me it was 3000 rounds and one set back...
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Joined: Oct 2008
Posts: 7,263
Campfire Tracker
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Campfire Tracker
Joined: Oct 2008
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One theory is that if the angles of the cartridge shoulder converge inside the neck it reduces erosion. PO Ackley may have come up with this theory, could be conjecture and advertising, dunno.
Neck length the conventional rule is one caliber minimum.
3100 fps is or can be an accuracy node for the 139-143 gr. bullets. I doubt the SAUM could exceed this that much unless it had a really long barrel and run at higher pressures. Even the 6.5x300 Weatherby doesn't get a whole lot more velocity.
Either way the 6.5 SAUM or 6.5-06 AI have a lot of potential.
Still doesn't fully explain the barrel life difference between the 6.5 x.284 and the SAUM. Where does the 6.5 Rem. fall on barrel life?
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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Joined: Jun 2011
Posts: 10,851 Likes: 48
Campfire Outfitter
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Campfire Outfitter
Joined: Jun 2011
Posts: 10,851 Likes: 48 |
The average time it takes for a bullet to leave a hunting length barrel is in the 1 millisecond range. So, assuming a barrel life of 2500 rounds, the barrel life is 2 and 1/2 seconds 
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Joined: Dec 2003
Posts: 2,293
Campfire Regular
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Campfire Regular
Joined: Dec 2003
Posts: 2,293 |
IIRC using a larger than 'normal' case for a bore size and slower than 'normal' powder for increased barrel life was the reasoning behind the design of the 220 Howell. I haven't seen Ken post in a long time, but a search should pull up what he's posted in the past. I think you have that backwards... I've read many times that the faster the burn rate of the powder the less the throat erosion and therefore the greater the barrel life. Here is a pretty good read on barrel life... http://benchrest.com/showthread.php?80875-Barrel-LifeBob
Many who have freedom have no idea where they got it....
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Joined: Feb 2004
Posts: 17,113 Likes: 1
Campfire Ranger
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Campfire Ranger
Joined: Feb 2004
Posts: 17,113 Likes: 1 |
I don't think 3100 with a 140 out of that case is leaving a lot on the table. I get that with the long 140-grain TTSX bullet out of my .284 with a 23" tube.
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Joined: Dec 2007
Posts: 16,143 Likes: 1
Campfire Ranger
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Campfire Ranger
Joined: Dec 2007
Posts: 16,143 Likes: 1 |
I don't think 3100 with a 140 out of that case is leaving a lot on the table. I get that with the long 140-grain TTSX bullet out of my .284 with a 23" tube. And a BC of .412. Compare that to a 6.5 140 VLD's BC of .612, or the .618 of the Hybrid.....
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Joined: Jun 2006
Posts: 46,067 Likes: 3
Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
Posts: 46,067 Likes: 3 |
.284? Apples and oranges with different bores sizes.
Not directed at you aalf, but I thought folks knew that.
Not to mention that I qualified the statement as pertaining to the 6.5 SAUM case.......apples, oranges, and kumquats.
A wise man is frequently humbled.
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Joined: Jul 2007
Posts: 8,200
Campfire Outfitter
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Campfire Outfitter
Joined: Jul 2007
Posts: 8,200 |
I don't think 3100 with a 140 out of that case is leaving a lot on the table. I get that with the long 140-grain TTSX bullet out of my .284 with a 23" tube. Not a valid comparison. Bearing surface is shorter. Compare the 6.5 140 to the 7mm 160 or maybe the 175. A more valid comparison. 7mm velocity will be less because of the added friction of the longer bullet bearing surface.
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Joined: Jun 2006
Posts: 46,067 Likes: 3
Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
Posts: 46,067 Likes: 3 |
It's not a valid comparison because:
1) it's not the case I was talking about (6.5 SAUM, otherwise known as the subject of this thread); and
2) the bore size is larger.
A wise man is frequently humbled.
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Joined: Jul 2001
Posts: 60,138 Likes: 9
Campfire Kahuna
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Campfire Kahuna
Joined: Jul 2001
Posts: 60,138 Likes: 9 |
Tejano,
Apparently you missed my earlier post in this thread. The military has done considerable research into barrel erosion, because they burn out a LOT more barrels than any of us. Their extensive tests have proven that a steeper shoulder and longer neck do extend barrel life.
While the 6.5 SAUM's shoulder angle isn't quite as steep as the 6.5/.284's, the difference ain't much, and both converge inside the neck.
But the 6.5 SAUM's neck is almost .30" long, while the 6.5/.284's is about .27".
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Joined: Oct 2008
Posts: 7,263
Campfire Tracker
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Campfire Tracker
Joined: Oct 2008
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Nope, I got it thanks. Didn't mean to be redundant, it just still seems like an anomaly the difference that .03" of neck would make, but also it's the loading methods too I'm sure.
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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Joined: Feb 2004
Posts: 17,113 Likes: 1
Campfire Ranger
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Campfire Ranger
Joined: Feb 2004
Posts: 17,113 Likes: 1 |
I don't think 3100 with a 140 out of that case is leaving a lot on the table. I get that with the long 140-grain TTSX bullet out of my .284 with a 23" tube. And a BC of .412. Compare that to a 6.5 140 VLD's BC of .612, or the .618 of the Hybrid..... Check the difference at 400-500 yards. And as I've said before, with good LRF, and turrets and/or a ballistic reticle and it MAKES no difference. We now can PLACE the bullet, ...even if it drops more
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Joined: Feb 2004
Posts: 17,113 Likes: 1
Campfire Ranger
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Campfire Ranger
Joined: Feb 2004
Posts: 17,113 Likes: 1 |
The obviously obscure point is, unless you are shooting to 1k yards competitively, you are chasing your shadow. Which means I'm talking hunting scenarios.
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Joined: Feb 2014
Posts: 65
Campfire Greenhorn
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Campfire Greenhorn
Joined: Feb 2014
Posts: 65 |
I noticed on snipers hide the new big caliber is the 6.5 Saum. They tout the barrel life that they are getting from this caliber. I noticed that they are keeping the pressures down around 58000. My question to the gun writers is won't you get good barrel life from any caliber if you keep the pressures down. The goal was to match the pressure of the .308 winchester and by doing this equal the barrel life. So far that seems to be the case. There is a lot of 4S shooters reporting 3000 rounds fired with no or little change in accuracy. As I understand it pressure is the key here, not heat as posted above. Heat is a factor in barrel life but not as much as you think. The link / info to the barrel life spreadsheet is not valid IMO.
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Joined: Jul 2001
Posts: 60,138 Likes: 9
Campfire Kahuna
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Campfire Kahuna
Joined: Jul 2001
Posts: 60,138 Likes: 9 |
The military studies on barrel life have all concluded heat is THE major factor.
Of course heat is a by-product of pressure, but in rifle cartridges the major factor in heat level is the bore-to-powder ratio.
If pressure were the major factor in barrel erosion a .300 H&H (58,000 psi SAAMI Maximum Average Pressure) barrel would last longer than a .308 (62,000 SAAMO MAP). It doesn't.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Joined: Jul 2001
Posts: 60,138 Likes: 9
Campfire Kahuna
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Campfire Kahuna
Joined: Jul 2001
Posts: 60,138 Likes: 9 |
Tejano,
Neck length becomes more obvious as a factor if you look inside some rifle barrels with a bore scope. The most erosion takes place immediately in front of the mouth of the case, and drops off noticeably further down the bore, whether 1/8" or 2". A longer neck protects the part of the bore that erodes first and worst.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Joined: Sep 2006
Posts: 1,878
Campfire Regular
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Campfire Regular
Joined: Sep 2006
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For what it's worth, I believe the GAP boys are claiming that their 6.5 SAUM/H1000 load runs quite cool.
Empirical results rule!
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Joined: Feb 2014
Posts: 65
Campfire Greenhorn
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Campfire Greenhorn
Joined: Feb 2014
Posts: 65 |
Apples and oranges. The heat that a m4 or the like produces is not the same as a hunting or comp rifle. We don't shoot ours till they are smoking - not the same. Heat is part of it but not as much.
Last edited by rifleman700; 03/15/14.
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