Yes you will have to buy bases unless you bought rings that will clamp right into the grooved receiver. I have a set of Warne rings on my Tikka that clamp into the receiver and they are nice. I wondered when I put them on if they would stay put over time under the recoil. It's been several years now and they haven't budged a bit. I like the idea of eliminating the bases from the equation, just less screws that could possibly work loose.