Like the "Hitman" said , two in front and one in back. I have had excellent results with Leupold Rifleman Vertical split rings on my Freedom Arms .475 Linebaugh shooting heavy loads and also on an SSK .376 Steyr Encore that RIPS Butler Creek Lens covers in half every 5 - 10 shots. It really matters how heavy of an optic you are putting on your gun. The heavier the optic the more stress on your mounting system.