I use a Redhead boresighter that I purchased from Bass Pro Shops for $50. Easiest thing in the world to use and the first shot puts me on paper everytime.
The Leupold Zero Point Magnetic Illuminated Boresighter I mentioned above is nice for another reason. You can put it back on the rifle and record the settings on it after firing at the range and next time get it right on the money without firing a shot. Well, maybe one.....
(The only laser boresighters I'm familiar with are the "cartridge case" ones. The ones that go in the end of the barrel might be better but a gunsmith neighbor boresighted a rifle with one of those one time and it wasn't very close).
If someone wants a laser boresighter for a .300 Win Mag. PM me and it's theirs. First come first serve.