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I thought they were a 1 in 9 like the Model 70 Winchester's
Gerry.
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Yup, 1 in 9. My CDL .264 barrel is a tomato stake now... Keep thinking about having one built but it will be 1:8.
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Campfire Kahuna
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Campfire Kahuna
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Actually a 1-9 would work fine in western Colorado, just as well as a 1-8 a lower elevations.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
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The idea was for it to be a gun for Texas/Mexico/Arizona Whitetail and Coues so the elevation here (which is still only 4,500ft) wasn't a real factor and I don't imagine regretting a 1:8 if I get a choice.
I'm sure there is better terminology but when I finally had enough of my CDL the gunsmith showed me how far off the bore was from being in the center of the barrel at the crown then with a bore scope he showed me the marks from where the bit had "chattered" its way down the bore. Not Big Green's finest rifle but I still drool over a .264 Sendero II.
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So the factory twist may not stabilize the Berger vlds?
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Joined: Feb 2015
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Campfire Greenhorn
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Campfire Greenhorn
Joined: Feb 2015
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As long as your gun has a magnum bolt face, magazine and follower; my thought would be to rebarrel it to an 8 twist 26 Nosler. That would be a really go fast hunting gun. Just a thought.
Presidents 100-'97 Distinguished Rifleman-'81 NRA Benefactor Artillery lends dignity to what would otherwise be a vulgar brawl.
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So the factory twist may not stabilize the Berger vlds? I've had two, bone stock 700 .264 WMs and had no problems with the Berger 140s or Scenar 139s at sea level.
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I shot the 140 VLDs in my pre 64 westerner. They shot fine.
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Campfire Kahuna
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Campfire Kahuna
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A lot depends on temperature as well as elevation. In warmer weather (typical of Texas) a "slow" twist will stabilize bullets that the same twist won't in truly cold weather--a potential problem here in western Montana, though it's somewhat counteracted by the higher elevation.
The rule-of-thumb is that every 5000 feet of additional elevation acts about like a 1" faster twist. So if you have a 1-9 twist 6.5mm barrel and don't shoot at any lower than 4000 feet in elevation, it will stabilize even with 140 Berger VLD's even at -20 Fahrenheit. The stabilization won't be enough to optimize ballistic coefficient, but the bullets will remain point on and probably be pretty accurate.
The 4000 feet is my situation, by the way. The town we live in is at 3900 feet, right along the Missouri River in the bottom of the valley, so every place else around here is even higher, including the two ranges I shoot at. As a result a 1-9 twist works for any 6.5mm round with 140 VLD's.
Even at sea level a 1-9 should stabilize (but not optimize) a 140 VLD down to -20 degrees. The reason many prefer a 1-8 twist isn't because it won't keep a 140 VLD point-on, or prevent them from shooting accurately, is that BC isn't optimized until the Sg is 1.5 or more.
Sg is a number assigned to a bullet's stability in a certain twist and conditions, with 1.0 the minimum needed for stabilization. But BC will increase up to a 1.5 SG, which is why many prefer a 1-8 twist, not because a 1-9 twist won't stabilize long 140-grain bullets. But it will result in a 1.5 Sg at 7000 feet above sea level, at a typical fall hunting temperature of 35 degrees.
Bullet stabilization isn't a simple either/or situation. It's affected not just by rifling twist, but by temperature, elevation and whether or not you want the highest BC the bullet's capable of.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
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Thanks, just wondering how the vlds will shoot. I run 130 grain sciroccos now. The shoot pretty well.
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