I have a 13 year old Darton viper with the energy wheels in between round and cams, My arrow weight is 410gr (carbon) total, my draw length is 29" and my pull is 62 pounds, What speed do you think I am getting from this bow? Thx, Elmer
I'll use a median of 297 fps IBO speed. That is at 30"/70 lbs.
take off 10 fps for the 29" of draw
- 287
Take off 16 fps for the 8 pounds under 70
-271
5 grains added in arrow weight above IBO (5 grain/lb = 350 grain arrow) - 1 fps 410 - 350 = 60/5 = 12 fps
259 fps Assuming you have nothing on the string. Realistically, with a peep, loop, and 2 small string silencers, I'd say your around 245 - 250 fps.
410 grain arrow at 247.5 fps would be 56 ft lbs of KE which is plenty for anything in North American provided your bow is tuned and you make a good shot with a razor sharp broadhead.