those gains, on primo and dbols, are uncommon... but possible nonetheless.
it depends on his genetics, cycle history, and diet.
if this is dude's first cycle (or first after a very long time off) and he's a genetic freak who eats all day long then sure.. those gains are possible.
in 5-6 weeks, the combo of 600mg primo/30mg dbol/6k cals a day can most certainly pack on 24 pounds of WEIGHT (notice i did not say lean body mass).