I've shot 3 gun for about 6 years now. I use 55 bulk for everything inside 200 yards. 200 and out I use a 75 or 77 gr load. I hand load using 75 grain horandy BTHP now, but I used MK262, 75gr Hornady match, 75gr Hornady steel match, etc, before I stared reloading.
75gr Hornady steel match was great until they quit producing it. Now many shooters are using the 75gr Hornady match in the brown box. I would try the CBC 77gr. When PSA has it in stock, it is a good deal. edit: try the PPU 75gr match.
I wouldn't say you need BH or IMI, but a heavy match load is better for long shots, IMHO.
Edit: This is assuming you have a 1:8 or 1:7 twist barrel.
The better BC, better wind resistance, etc, is good justification for keep a mag or two in your bag for a match that has shots over 200 yards.
Edit: M193 is NATO training ammo. There is much better ammo for HD.