6.5-270 (257) Wby Mag...What do I need?

Mike from Texas

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It should work fine. Just check the reamer neck diameter and the diameter of the final neck with the projectile you intend to use.

I will send the reamer guy a couple of dummy loaded rounds. Only thing I am unsure of is how much free bore it should have.
 

338 dude

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Put the 19Lb striker spring in today...

Finally got some data points and I have to pull about of 20 rounds of ammo because they would be way too hot.

I was not getting any of the usual pressure signs with this Nucleus action. Then it suddenly locked up with the next one grain increase in powder. I actually had to kick the action open with the rubber sole of my boot.

But holy cow the barrel was putting down some impressive speeds.

The rifle was shooting this target (yes, I biffed one) @ an average speed of 3427 fps with an ES of 27 from 10 rounds, and then it locked up with one more grain of powder from this load.

Again, bipod and rear bag out of the back of my pick-up. Lased 101 yards.

View attachment 111422

28" barrel, 1-8 twist, Magnetospeed on the end of the barrel...150 gr Sierra Match King. Necked down 270 Wby brass.

If I step down the powder by two grains from the above load I still get an ave speed of 3372fps with an ES of 8 for 5 rounds.

What kind of speeds can a reloaded 26 Nosler put down?

I have 6.5mm 160gr Matrix bullets inbound.
I would run with the 3372 load
 

Longtooth32

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Thanks for resurrecting this thread. It is starting to warm up outside. I have 160 Matrix and 156 Berger on the self to work up. Looking for mid to low 3300fps with the 160s and with the 156 Bergers...
 

Hoss50

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Apr 7, 2019
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A 6.5/257 weatherby choice was on the table when I had to make the choice of what caliber I wanted when I rebarrled my 257. 257, 264 win, and 6.5/257 were my thoughts. I ended up keeping the quarter bore with the new barrel.
 

Mike from Texas

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Thanks for resurrecting this thread. It is starting to warm up outside. I have 160 Matrix and 156 Berger on the self to work up. Looking for mid to low 3300fps with the 160s and with the 156 Bergers...
Resurrecting this one again. I finally bought the parts to put this rifle together. I’m still on the fence about 264WM vs 6.5-257 Wby. I like the longer neck in the WBY and I like the Venturi shoulder on the WBY case.
I’m still unsure how much freebore I should have the reamer built with (257 Wby has .375”) and I’m exploring die options as well.
I already have a 257 Wby, I’m wondering if I can just use the 257 Body die and the proper bushing and expander mandrel to go up to 6.5.
Did you ever get you build finished and if so what kind of results are you seeing? I plan to run one of three bullets:
Berger 153.5 Long Range hybrid target
Berger 156 EOL
Matrix 160 VLD
In measuring H2O capacity the Norma 257 Wby brass has 1.6grains more capacity than the Winchester 264WM brass that I have.
 

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