New build 264 Win Mag vs 6.5/257 Weatherby

Mike from Texas

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I’m working on a new build and I’m torn between these two cartridge options.
On one hand I’m trying to stay with more traditional cartridges but 264 WM isn’t exactly mainstream.
I already have both brass and dies for 257 Wby and 264 WM so that’s not a deciding factor.
I do prefer the longer neck of the Weatherby case, especially since this will be set up for the 156 EOL bullets and I like the Venturi style
neck of the Weatherby case; I think there are merits to the design. The Weatherby case has 1.6 grains more water capacity. Not sure what that translates into for powder, but likely not enough to matter.
On the other hand the Weatherby is definitely not mainstream and would definitely be a reload only option which for me isn’t a problem but may be for others if for some reason I had to sell down the road.
I dunno, I know which way I’m leaning but just looking for feedback from others who have experience with decisions like this or with either of the cartridges mentioned.

Build parts specifics:
Kelbly Atlas Tactical
Proof 28” Sendero, 8 twist
AG Composites Visigoth
Hawkins DBM
Trigger Tech Diamond
 

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Northkill

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Thing is, if you build the 264 Mag throated for the 156 Bergers, it will be best suited to a reloader anyway. Chances of the minimally available factory ammo satisfying an astute shooter are slim. Go with your preference. MHO. 🤠
 

Mike from Texas

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Thing is, if you build the 264 Mag throated for the 156 Bergers, it will be best suited to a reloader anyway. Chances of the minimally available factory ammo satisfying an astute shooter are slim. Go with your preference. MHO. 🤠
Thanks for the response. I am having the reamer built so your point is valid on the 156 throating.
 

Hespco

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I've been shooting a 264mag since 1964. Can't imagine going to the trouble of a wild cat 6.5x257 WBy to achieve the same results. The 264 is very much alive & well. There is factory ammo & reloading components available. You see many on these forums who build a special something they like. Then you will see some of these custom rifles up for sale at a considerable loss to the owner. Can be tough to sell a special something. A standard 264 with a factory throat has a much better chance at resale. A special throat, even though it may appeal to you can be a turn off to a potential buyer. Take your time & be very carefully of your decision .
 

FEENIX

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I’m working on a new build and I’m torn between these two cartridge options.
On one hand I’m trying to stay with more traditional cartridges but 264 WM isn’t exactly mainstream.
I already have both brass and dies for 257 Wby and 264 WM so that’s not a deciding factor.
I do prefer the longer neck of the Weatherby case, especially since this will be set up for the 156 EOL bullets and I like the Venturi style
neck of the Weatherby case;
I think there are merits to the design. The Weatherby case has 1.6 grains more water capacity. Not sure what that translates into for powder, but likely not enough to matter.
On the other hand the Weatherby is definitely not mainstream and would definitely be a reload only option which for me isn’t a problem but may be for others if for some reason I had to sell down the road.
I dunno, I know which way I’m leaning but just looking for feedback from others who have experience with decisions like this or with either of the cartridges mentioned.

Build parts specifics:
Kelbly Atlas Tactical
Proof 28” Sendero, 8 twist
AG Composites Visigoth
Hawkins DBM
Trigger Tech Diamond

Sounds like that action is screaming for a 6.5-300 WBTY. 😇
 

Mike from Texas

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Sep 7, 2013
Messages
611
Location
North Texas
I've been shooting a 264mag since 1964. Can't imagine going to the trouble of a wild cat 6.5x257 WBy to achieve the same results. The 264 is very much alive & well. There is factory ammo & reloading components available. You see many on these forums who build a special something they like. Then you will see some of these custom rifles up for sale at a considerable loss to the owner. Can be tough to sell a special something. A standard 264 with a factory throat has a much better chance at resale. A special throat, even though it may appeal to you can be a turn off to a potential buyer. Take your time & be very carefully of your decision .
257 Wby is super easy to convert to 6.5mm. I use an expander mandrel to neck up to .262” (.002” under bullet diameter) and that’s literally it.

The points you make about the 264 is the main reason it’s still being considered.
One thing also that appears to be a advantage with the Wby case design is I believe it can be pushed harder than the 264WM. I’m pushing my 257 Wby well beyond published max loads with (so far) no loss of accuracy or damage to the brass. I’m currently pushing a 115 Berger at 3600+ and only seeing very faint ejector marks but no other signs of pressure. I suspect that’s due to the large amount of free bore on Weatherby chambers. Which brings up another uncertainty and that is if I decided to go with the Weatherby case, what freebies would I have built into the reamer? The 257 Wby shows to have .375” of free bore.
 

Hespco

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In my 264 WM 26" Bbl. I'm driving Nosler 140 AB's at 3229 fps. Hammer Hunter 121gr at 3450 fps, & 100gr Barnes TTSX at 3700+ fps. Not the slighest sign of over pressure in any of these loads. It's just a matter of the right powder. I'm using off the shelf Win & Rem brass. Another plus for the 264 WM is relatively inexpensive 7mag brass can also be used. A simple neck down to 264, instant 264 brass. Who knows what the further holds. Wish we were close so I could show you some of the 264 positive virtues.
 

Mike from Texas

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Messages
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In my 264 WM 26" Bbl. I'm driving Nosler 140 AB's at 3229 fps. Hammer Hunter 121gr at 3450 fps, & 100gr Barnes TTSX at 3700+ fps. Not the slighest sign of over pressure in any of these loads. It's just a matter of the right powder. I'm using off the shelf Win & Rem brass. Another plus for the 264 WM is relatively inexpensive 7mag brass can also be used. A simple neck down to 264, instant 264 brass. Who knows what the further holds. Wish we were close so I could show you some of the 264 positive virtues.
I’m not ruling out the 264WM by any means yet. I’m listening to all input. I do appreciate your feedback.
 

SeboCreek

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Your 257 Weatherby necked up to 6.5 is the rifle built for me by McWhorter. So far 3 loads worked up. 140 gr Berger shooting 3250, 139 Sledge Hameer at 3288 FPS, and 123 Absolute Hammer at 3515 FPS. All these loads show no pressure signs, and probably could easily push faster, but worst group of all three is .42 Moa with the 123 gr. Just FYI.
 

FEENIX

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I considered it, but I’m trying to keep the recoil down. And I’m not sure it’s worth the extra powder for the probable gain.

On the other hand, I COULD set it up as a switch lug; 6.5-300 and 300 Wby.

Dang it.
The only reason I mentioned it is that it gives you the flexibility to reload and use factory ammo (if and when you decide to sell it, as you noted).
 

MagnumManiac

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Feb 25, 2008
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My custom 264WM is a switch barrel on a trued Rem 700, 8” twist 29” barrel.
I run the brass up to within .010” of chamber end and keep it there, it adds an additional .030” of neck. There is absolutely no data that supports better accuracy from a longer neck, it has been proven to slow throat erosion, as have shoulder angles above 30°.
My throat has been cut for the 156g Berger, works out to be .240” long, the 142g ABLR is also perfect with this throat, as is the Sierra and Berger.
If you decide on the 6.5/257 Weatherby, the standard throat of .376” is about the only option, you won’t get the velocity you’re after if you go shorter.
I run a 270 Bee, it gets velocities beyond the book too, but I have actually pressure tested the loads and they can be 65,000psi book max or less depending on whose manual you look at. If you get substantially higher velocities, then you will be getting higher pressure regardless whether your brass shows it or not.
There is also no data that supports the Venturi shoulder enhancing gas flow, it’s novel idea in fluid mechanics, but a rifle barrel and chamber are not a down pipe or intake manifold.
I don’t see the point going to the Weatherby when the 264WM will do everything the Weatherby can.
The 264WM has never disappointed.
Just my 2c.

Cheers.
 
Last edited:

Mike from Texas

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Joined
Sep 7, 2013
Messages
611
Location
North Texas
My custom 264WM is a switch barrel on a trued Rem 700, 8” twist 29” barrel.
I run the brass up to within .010” of chamber end and keep it there, it adds an additional .030” of neck. There is absolutely no data that supports better accuracy from a longer neck, it has been proven to slow throat erosion, as have shoulder angles above 30°.
My throat has been cut for the 156g Berger, works out to be .240” long, the 142g ABLR is also perfect with this throat, as is the Sierra and Berger.
If you decide on the 6.5/257 Weatherby, the standard throat of .376” is about the only option, you won’t get the velocity you’re after if you go shorter.
I run a 270 Bee, it gets velocities beyond the book too, but I have actually pressure tested the loads and they can be 65,000psi book max or less depending on whose manual you look at. If you get substantially higher velocities, then you will be getting higher pressure regardless whether your brass shows it or not.
There is also no data that supports the Venturi shoulder enhancing gas flow, it’s novel idea in fluid mechanics, but a rifle barrel and chamber are not a down pipe or intake manifold.
I don’t see the point going to the Weatherby when the 264WM will do everything the Weatherby can.
The 264WM has never disappoint
Just my 2c.

Cheers.
So did your reamer maker come up with the .240 throat dimension or did you specify that?
 

MagnumManiac

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Feb 25, 2008
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No, I used a throating reamer to extend the throat to suit. I do my own smithing.
I used a Manson SAAMI spec 264WM reamer.
I rarely use a custom reamer on SAAMI cartridges, a throating reamer with a floating pilot does a great job.

Cheers.
 

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