BEWARE!
I've had 2 M700's that would not reliably handle the slightly larger case head diameter of the Lapua brass.
A shooting acquaintence of mine - also a HP Sil shooter - had the same problem, and ended up using Remington Brass.
Before doing this, send me your address and I'll send a few empty Lapua 6.5x55 cases for you to try BEFORE you commit.
If they don't work well with your existing bolt face, you could still use the lapua brass if you have a smith do a little bit of reaming on the inside of walls of your bolt face.
You can contact me at grbuss@yahoo.com.
Gringo