take it to a shop and have them adjust it, set it up for you and tune it for you. thats the only way youll get anywhere with it. how the heck did you come up with 51lbs by drawing it back with no scale?? there should be a sticker under the bottom limb pocket that states what limbs and everything are on it. i dont think they make 40-50..could be wrong.

also you have to tighten BOTH limb pocket bolts..and do so equally to have it set right. it sounded like you just cranked on one. my advise is take it to a shop....it probably needs alot of adjusting to fit YOU and tuned FOR YOU.....