Heavy is really a function of what game you are shooting.
If you are shooting Palma/TR, 156gr's are it.
if you are shooting precision rifle, then you need to see the course of fire and what makes most sense.
If you are shooting F class, most are gravitating to 185gr to 230gr bullets. A lot of what is best boils down to what you can find, shoot accurately and handle the recoil for.
Big matches have had shooters using 155 to 168gr bullets doing very well. Lighter bullets typically get bounced around more BUT if you know your wind dope and can read the wind, you can do a very respectable job.... even podium.
I personally shoot 200gr Hybrids and 208gr Hrn BTHPs. I might be one of the very few that couldn't get the 185's to work which is truly bizarre.
Jerry
PS as a point of reference, at the 2013 Worlds - Team USA used 185's (pretty sure), Team Canada used 185's, Team GBR used 155.5's. Not sure what the Aussie's shot - my guess would be 185's?. Was not much difference in our scores. All teams shot on the same relay and pretty close proximity