1 in 7.5 Twist 257 Weatherby

GLTaylor

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Oct 11, 2019
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I built a 1:7.5 twist 6.5-284 for the 131 ACE. It shoots them and Hammers very well and fast. Never really intended shooting little bullets fast. Got other rifles for varmints - not as hard on the barrel.
Sorry, I meant 25-284
 
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Warbird2006

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Apr 15, 2012
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Looking for a bit of help on getting the right twist on my 257 Weatherby build. I want to be able to shoot the heavier black jack bullets so I intend to use a 1 in 7.5 twist, but I wonder how much that will hinder me on the lower end weights. Can I still shoot the 115 VLD or the Barnes TSX 100 Grain accurately? I appreciate any and all advice and experience you might lend. Thanks!
Solution is very easy, my friend. Have one rifle built for your custom black jacks, and the second one for the factory ammo. :)
 

Mike Matteson

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Jun 26, 2017
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Berger Bullet's has a stability analysis calculator to determine twist rates. Just how good this is I don't really know, but I don't think they would put something out that incorrect either. It could be only for their bullets too. I've been looking at twist rates for a 6mm AI or along that line of thinking. The only different is I am looking at 105 grs to 115 gr bullets to shoot only. Bartlein builds barrels with twist rates that start out in the chamber at one rate and continues to increase as it reaches the muzzle. In my mind that see to work out, by lowering the chamber pressure at the start by not having a high rate of twist to start with. Achieving the twist rate at the muzzle or withing a few inches of the muzzle. I am looking at a rifle to shot out to 700yds, and not for elk either. Achieving velocity or about 3200 fps at muzzle with at 1-7 twist. Looking for input.
 

highdrum

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Nov 30, 2008
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Montana
Talk to the guys at blackjack. They ran several factory loads through an 7tw or 7.5 tw 25-06. Don't believe they had bullet blow ups. I would think that 115gr Berger would hold together. I have a 28" benchmark carbon 7.75 tw on order for the 257 blackbird, which is essentially a beltless 257 wby.
 

fmuguira

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Nov 6, 2010
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1-8 twist in 25-06 AI at 3000 feet elevation is working great for 3 different rifles. 3 groove Lilja. 3100 FPS

That 257 WB should do equally as well.
 

highdrum

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Nov 30, 2008
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Montana
I have a 7 twist 25-06AI and have had no problems shooting 115's and lighter. I had no problem with the 100 gr Swift Scirocco going 3650.
What's ur barrel length? How fast have you pushed the 131 in the 7tw? Curious if you've had any blowups.
 

flyinstroke

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Jul 8, 2019
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Texas
131’s only going 3200 at the moment. That’s node I can reach. The next node in my barrel is 3400 and haven’t gotten to that with out blowing primers. Barrel is 26 inch Sendero contour. Savage long action and a McGowen barrel
 

Mike Matteson

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Jun 26, 2017
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295
I am wondering how many time you are able to use the case, and the primer just doesn't fall out of the prime pocket when reloading the case? If you are blowing primers, you have gone beyond the safe pressure limits in the chamber. Flat primers are one thing, but blowing primers are two stage over flatten primers. you better quite while you still have a head on your shoulders.
 

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