Originally Posted by
bigbulls
Slow and heavy wins every time. The bow is quieter, broadhead flight is better, wear and tear on the bow is reduced, KE and momentum is higher initially and is retained better over distance.
You would be surprised at how little trajectory difference there really is when comparing light and heavy arrows out of the same bow.
For instance...
A 350 grain arrow shot at 340 fps and sighted in at 20 yards will drop 12.6 inches at 40 yards. It will start out with about 90 foot pounds of KE.
A 500 grain arrow shot at 290 fps and sighted in at 20 yards will drop 17.4 inches at 40 yards. It will start out with about 93 foot pounds of KE.
I think Bibbulls estimates are even being a bit conservative. The normal average speed loss/gain is roughly about 1 fps per 5 grains of arrow weight. So in his estimates (or calculations) the speeds would be 340 and 310 from the same bow with the 350 and 500 gr arrows respectfully - all else being equal. So the trajectory would be even flatter for the heavier arrow and KE greater.
Additionally, I believe it is also determined by what you are hunting. A big burly animial like a moose, big bear, bison etc have heavy ribs and a lot of body mass to get through. Your heavier arrow stands a much better chance of pushing through all that mass of muscle and bone.