257 Weatherby with 128gr HH Data?

[dogz]

Update.

I bought a lab radar. Here is the info. This is for MY Rifle, start lower. This load is on the spicier side I think.

257 Weatherby Mag
1:7 twist barrel from Oregon Mountain Rifles
Norma Brass
128gr Hammer Hunter
70.0gr H1000
GM215M primer
3.50 OAL
3345fps
Lots of freebore.

Sub 1/2" MOA. The 3 copper bullets in the picture are a group at 500 yards.

The 3 lead bullets are 135gr Bergers @ 500yards with a starting load. Very accurate, but only 3140fps.

Barrel length?

 

[Hoss50]

Barrel length?

26"

 

[Blackdirt Cowboy]

That's good info. I'm waiting on the smith to finish up my 257 wby. I can't shoot the 128 hammer as I have a 7.5 twist 28" barrel. I'm going to try the 125 hammers. I was hoping to get to 3400-3500 fps. Looks like it's doable.