Used as front base on : Browning A-bolt, A-bolt 22, WSSm
 
Use as rear base on:  Browning A-bolt, A-bolt 22, BBR L/A, S/A Ruger M44, Carbine, 96/44 (old models, round receiver)
Winchester 70 Long & short acations (with same hole spacing front & rear) 670,770