If you can't find your manual use the formula.
BC = Bullet weight(gr) divided by (7000 x Cal squared x ff)
ff is the form factor for the balls velocity. 1.4 for more than 1300ft/sec, 1.7 for 1000-1300ft/sec, and 2 for less than 1000ft/sec.
220gr bullet BC = 0.0752
143.4gr bullet = 0.0491
This came from Hatchers notebook I bet its not far away from your handbook.