A JHP will be longer than a FMJ. So if you load to the same OAL your pressure will be a little higher. Your gun is different than the one than they used also.
So start at the low end and then work your way up looking for an accurate combo. Once you find that stop. Running at or near max just puts extra wear and tear on you and your gun.
What powder were you thinking about using?
I am fond of win 231 and WSF in 40 SW with 180gr.