With Cramer's not everything is listed and progression doesn't always fly either . I have a B4 . The B1 ,2,&3 are 270-110,120, and 130 gr (maybe it's 100 ,115 ,130) B4 is the same shape and it would follow that it should be a 270-150 .......it isn't it's a 7mm 130 ........ I've made more references than Google had when I searched it . Whatever it's worth .