Ok I' ve been doing some research myself on this flattest tragectory.

In a 7mm STW with 120grain zeroed at 100 you get a 27.0 inch drop at 500.
In a .243 with 55 grain zeroed at 100 you get a 29.1 inch drop at 500


.220 swift = 33.8 inch drop at 500 with 40 grain bullet, the weakest 1457 fps
.22-250 = 32.7 inch drop at 500 with 40 grain bullet, the fastes 4150 velocity
.243 = 29.1 inch drop at 500 with 55 grain bullet
.257 wby = 30.1 inch drop at 500 with 87 grain bullet
.270 wby = 32.3 inch drop at 500 with 100 grain bullet
.300 wby mag = 31.9 inch drop at 500 150 grain bullet, the stongest 4316 fps
7mm STW = 27.0 inch drop at 500 with 120 grain bullet
7mm STW = 31.3 inch drop at 500 with 140 grain bullet, the slowest 3500 velocity
6mm Rem = 30.2 inch drop at 500 with 55 grain bullet