I just recived a new PACT chronograph the Clint Gard XP I put in the data from Hodgdon information web site in the chrono it prints out different from what the Winchester 2004 catalog does I have tried different loads and can't get to match the catalog the catalog said that the 243 WSSM set in at 100yd it will only drop -3.9 @300yd I used the the max powder data with the lightest bullet traveling @ the fastest speed and the PACT shows it dropping -5.5 were does Winchester get their information

Factory data is quite often optomistic. Many use pressure test barrels of match grade and then provide that info for you to try and duplicate in their sloppy chambered, unstraight factory tubes

Have you double checked to make sure that your using the same zero range as Winchester? The 3.9" drop figure is probably for a 200 yard zero.

Is there a place to enter the height of the sight above the bore? If there is enter 1.5 inches, which is the �standard� for a scope then run your numbers again