What primers are you using ? Speer has found that that powder works best with their CCI 300, rather than their magnumn 350's.
Are you seating with one pass and crimping heavily with another ? A heavy, or very heavy, crimp is often necessary.
My favorite loads are 20 grs. of 2400 over a 240 gr. Hdy XTP or 19 grs. of the same powder with a 250 cast, SWC. Either load shoots 1.5-2 inches at 25 yds with iron sights from my 4 inch Smith.
