I dont think there is any reason to load 150 grains of powder for deer. I use 90-120 grains of powder and I have never had a deer run more than 50 yards after it was shot.(my longest shot was around 120 yards give or take a few yards.)
When I bought my first inline I knew nothing about muzzleloaders and I stuffed 3 50 grain pellets down the barrel followed by a powerbelt and shot at a target 50 yards away. The gun went off, the scope came back and hit me above my eye, My eye swelled shut and i got a few stitches. I have never shot 150 grains again.