I can't help you here, I reload my .257 Wby, the only factory ammo my gun has seen is the 3 shots that fired the group on the target that came with the gun.
I have heard in the past, that Nosler Ballistic tips were developing a reputation for opening up to fast at higher velocities and going to peices rather than penetrating, so I've stayed awy from them in the .257 Wby. Don't know how true it is, but I heard it from a reliable source that I trust.
From a reloading standpoint, I like a Hornady Interlock 117 grain boat tailed spire point in my .257 Wby.
It appears your interest is deer/big game??, if thats the case, I'd try several brands of factory ammo in the 115/120 grain range and see what groups best in your gun. 115/120 grain bullets in .257 have heavy big game jackets and penetate terrifically, and with the .257 Wby, you're not experiencing the velocity loss you experience with a lot of other calibers by going to the heaviest bullet available.
