The lightest bullet I have used in mine is the 200 grain Shockwave. I shot two deer with that bullet.
The first went through the front shoulder at 110 yards out the other shoulder and came to rest just under the hide on the far side. The deer went about 50 yards and fell over dead, the downside was there was no blood trail, the upside was I watched it go down.
The second was shot at a distance of 60 yards right behind the shoulder through the heart and lungs, complete pass through. The deer went about 60 yards, the downside was I didn't see it go down (too thick), the upside was the blood trail was 4-5 feet wide (no kidding) and a blind man could have found it.
Sure these light bullets worked, but I like saboted bullets in the 250-300 grain range. The 200 grain Shockwaves were propelled by 100 grains (volume) BlackMag'3 powder.