I don't remember what the max load is for the T/C Hawken, maybe 110 grains of RS. The Investarm(Lyman, Cabela) barrell is not rated as high by Investarm, it is 80 grains with a conical and 90 grains max with a round ball. I do not know why they rated the Investarm lower then T/C, the barrell appears to have the same wall thickness. Maybe fear of lawsuites is the reason.