Mine liked 12.5 grains of IMR 4198, Hornady 25grain bullets and Winchester small rifle primers. It is pretty important to make sure your powder measure is throwing very consistently or trickle each load or use an electronic measure to get them as close as possible. Remember, that is a small case and not alot of powder so any variance in the charge will have a greater effect on accuracy than something like a 30-06. The above load is slower {around 3700fps, IIRC} than the factory loads {4200??} for this rifle but it grouped very well for me.