gee, now i am almost embarrassed to admit that i prime!
usually to re-assure myself abt any bodywork that got done,
and to get better paint adhesion.
of course, i only have 2 tanks and 4 planes done on the shelf,
so i am still sticking to the tried & true.
i have used Floquil railroad primer, and also Tamiya Flat Black.
the Acrylic dries much faster, of course.
but the Floquil is very nice, if you have the time & ventilation.
ed.