Ive gotten good accuracy from the 69 SMK's with velocities around 2800-2850. I would assume the Lapua's could go the same speed.
I am sure they could be pushed faster but I am not one to chase pressure signs.
I'm running the 75gr Hornady BTHP out of my LTR at 2760 (avg), which is pretty in line with what Hornady lists for a 20" service rifle. I'd assume that with the slightly lighter bullet and appropriate powders, you'd be able to bump the velocity up into the range suggested by Wareagle....
Kaiser Norton