The farrel G force that I bought was advertised as picatinny, but the slots were a tad small for picatinny spec. I had a local friend open the slots up a bit to take my within spec TPS rings. The other otption is to get weaver style rings, but it was easier to have the guy up the street make everything fit. If starting new, I'd probably go with farrel base and rings, or farrel base and get weaver cross bolts from TPS.
