I have a 264 made in 1960, I have tried a lot of different weight bullets and brands. Best groups have been Nosler 140 partitions with 57.0 grains IMR 4350. Federal match primers It shot really well with 140 Bergers , but I don't like them on game. I like to shoulder shoot, so I don't have to wade through cactus to find animals. Bergers are not good for that.