Does anyone have experience with this crossbow (SA-Sports Empire Beowulf Crossbow) and/or SA Sports in general? Any recommendations? Also, does anyone know if there is a mathematical formula to figure out kinetic energy if given other variables such as: FPS, Power stroke length, draw weight, etc???? (I want to buy this as my first crossbow and determining factors for me are kinetic energy, draw weight, speed, and price -I found this xbow for $360). Any help or advice is appreciated. Thanks, and have a FUN & SAFE Independence day everyone!