Daniel-
Great looking rifle!
What a classic little sporter, I'm sure it could tell some stories...
Once you get it running, I'm sure it'll quickly become one of your favorites.
Work with a chronograph in your load development.
What you want is a load that shoots to the sights. I've seen some lofty handload velocity claims for the 256 mannlicher. You don't need sizzling speed with that 160gr bullet, it's a penetrating machine - very heavy for caliber, very high sectional density.
Let us know how it goes.
--Tinker
