Hodgdon manual shows a 70 gr Nosler BT with a start grain of 41 - 43.7 max gr's of Varget. Hornady manual shows a 70gr Hornady SP with a start grain of 34 gr- 39.7gr max of Varget. Both using WLR primers. Why the big difference of powder charges between the Nosler 70gr and Hornady 70 gr? Want to use the Noslers. Thanks for any help.