while it is very possible that 43 @ 28 will equal 47 @ 27, it really does not matter. With every bow or grip design a person will have their own ideal draw length. With straight gripped bows I draw 26&1/4", no matter if is a 90 pound or a 30 pound bow. If I take a target bow, put my weight on the back foot, anchor under my jaw,keep the arm body head and neck straight, I will draw around 28"; but if the deer is not acting like a dead target, it is pretty much safe from me hitting it before it runs away. Always shoot with you most accurate draw length and let the pounds be what ever you are comfortable with using at that draw length.