I had a lot of trouble understanding C5.3 - Bounding Firer. To me, it's terribly confusing and circular, and didn't cover the simple case of firing in the DFPh while under a motion counter.
When I cited section C5.3 as a poorly written section, I was actually including all of its subordinate sections, including C5.35.
Motion fire is covered in C5.35. C5.35 refers back to previous C5.3 rules, which then also includes case B [C5.2]. Short summary of C5.3 et. al.: +4 turreted, +5 non-turreted & double the lower dr if not currently stopped. The summary does not cover Gyro-stabilized vehicles or limited aim.
Section C5.35 specifically refers to motion fire in the MPh, but doesn't say anything about the DFPh. Other sections in C5.3 refer specifically to the MPh and AFPh, but motion firing in the DFPh is not mentioned. Since the MPh and the AFPh were specifically called out, it wasn't clear how to handle motion fire in the DFPh. Maybe it's obvious to the experienced player, but when I was trying to learn the game, it caused me lots of problems. I eventually found an errata for section C5.35 that removed the specific reference to the MPh and somewhat clarified this, but section C5.3 (and its subordinate sections) still could have been written a lot clearer.