retumbo might be a little slow burning for 180gr and seems to work better with heavier heads, but still feasible. as far as fps, i'm doing 3050 with 90.0gr using 220SMK's. if the 180gr is going to fast with retumbo, try H1000 instead. havent shot much 180s with it, but it was giving me nice groups with the 200s. i'm sure the 180s should work as well.
-brian