Calculating DSF

[KB0321]

Hey guys
I am calculating DSF and have been taught to shoot at Rtrans 75%. Going off the transonic range of Mach 1.2 - Mach .8, Mach .9 would be 75% of the way through the transonic range. The Kestrel instruction manual concurs with this and suggests shooting at a range where your remaining velocity is Mach .9.

However, the measurement in my kestrel 4500NV model for rtrans75% is higher than Mach 1. It seems to be measuring 75% on a transonic range of Mach 1.2 - Mach 1.

From what I understand:
-True MV at Mach 1.2
-Refine your BC at 75% through transonic range
-Refine again your BC at Mach .8

Is Rtrans75% measuring a transonic range of Mach 1.2 - Mach .8 or Mach 1.2 - Mach 1?

Thanks for the help

 

[corsair4360]

What do you mean by the term "DSF" in your question?

 

[KB0321]

What do you mean by the term "DSF" in your question?

Drop/Drag Scale Factor. Truing your ballistic coefficient to the trans/subsonic ranges.