So I have 3 of these frames and want to match them up. I was calculating swingweight with the TennisWarehouse calculator and all of them came in around 275 or so, this is with orginal grip wrapped with one yonex og, pete sampras damper and strung with a full bed of solinco tour bite 16L. Racket specs on TW says 333 SW. The rackets all weigh in around 11.9 to 12.1 oz, these are 4 3/8 if that makes a diff. They're not all strung with the same tension though not sure if that matters either. My question is why are my numbers way below on the sw? Is the TW calculator accurate? I'm using ruler and table method for balance is that accurate?