Rounded base picattany rail question

The Accu-Shot 3.35 inch 1913 Rail (BT15) rail is rounded at the bottom. Worked well on my FX Streamline and FX Bobcat.

https://www.amazon.com/dp/B003LSKLBQ/ref=cm_sw_r_tw_dp_U_x_m9b8DbRYPRASJ

1576017916_13822200825df01ffc2f3d24.07071092_Accushot BT-15.jpg