Shooting 150 grains of powder is generally a waste of at least 20 grains, if not more. Most tests show that gains in velocity are almost nil in standard legth inlines when you go above 120 grains. The exception being Triple7, in which case going above 100 grains is likely a waste (and darned hard on your shoulder!). Why burn extra powder for so little gain, so much more recoil, and more expense? Those that think they need to shoot three 50 grain pellets or 120 grains of loose powder "because they can" are likely not finding the most accurate load for their rifles.

Triple7 is some very "hot" powder so don't even think about 150 grains of it. Hodgdon specifies a max of 120 grains (at least they did last I checked). 70 grains of powder behind 300+ grain bullets should certainly kill ANY deer if the shot is good.