Mister Stanley makes a good point there. I use the 4 screw rings. Also another option is to look at Harrell,s new bases. They have a stop built in so you can put your rings against the stop to keep the rings from sliding. I don,t think cost any more than other bases. Or maybe less. They also have a web site. If they aren,t shown on the site and you want the bases for a round action give then a call. Nice people there. But if you have a Panda action I would op for the Harrells 4 screw rings.
John