Bowman something does sound wrong there somewhere.I shoot a Justice Vft and I chronoed mine at 70# 27" draw length 351 grain total weight gold tip hunter at 261fps.The liberty is supposed to be about 4 fps faster than the justice and with your 1 inch longer draw you should at least be gettin 280 out of it you would think.I know I am pullin 70 lbs but I am still at the 5 grain per lb limit like yours.have you checked your bow on a scale to make sure it is actually pullin 60lbs?I went to my dealers the other day and pulled back a new extreme vft the BC said 71# max and I told my dealer man that bow pulls smooth for as fast as it is.When we got to checkin it was actually turned down about 1 and a half rounds.Just thought if you have not checked it might look at it cause somethin sure dont sound right.I would think you could get 280 out of that bow easy with a 5 grain per lb arrow.Anyway good luck.