I have heard reports of little or no expansion on smaller deer, don't know if this is in combination of behind shoulder shots/ shortened barrels for moderators. I know that the factory loads are fairly pedestrian in velocity
I loaded some 150gr Mega's for my .308. They were easily the most accurate homeload I have managed to produce but I had several very noticeable ricochettes that scared the c**p out of me; so I stopped using them and pulled the rest of the loaded rounds. A good friend also had some factory loaded Megas that had the same problem. The lack of expansion mentioned above and their habit of ricochetting off into the distance suggests they may have a hard core. I wouldn't use them again.
120 grain are ideal for sika and will also work well on Red deer. Meath Red deer been small! a 140 grain bullet would also be good choice.
Norma 140 grain are expensive but from my experience a great round. I use 120 grain for Sika and never had any issues.