Hey Stealthy was this a 100 grainer or a 125? Either way coming out of a 55 lb. bow I think the head did quite well.
I have taken two nice bucks with the 125 first cut series. While they are not my favorite head they both performed well. One hit ribs going in and I didn't get a complete passthrough on a broadside buck although the tip of the head punched a hole in the far side. That was shot out of a Q2XL set at 67 lbs. The second buck was shot with a 70 lb Darton as it was quartering away (200 lb + buck). It entered the back of the rib cage on the right side and exited out the front left side of the chest taking out both lungs but never hitting a rib. The buck only went 60 yards.
Neither head showed much damage and gave good blood trails.
Give your Father my congratulations!