i might be wrong on this and anyone who knows better can chime in... but i think the model 12 series as well as the model 10's (police/tactical) and also the target series have triggers that can be set down to 8 oz. (that is if it is an accutrigger model)
I know my model 10 and both my model 110's came set at that from the factory...
if it is an accutrigger model, and you want to add more weight to the trigger just drop the action outa the stock and use the tiny little accutrigger tool that came with the gun from the factory (little knobby looking thing with a 1/2 inch long shaft with a slot in the end) and adjust it to where you want it
here is a link to the savage manual it explains the procedure better than i can:
if it is a pre-accutrigger model or has an after market trigger you may have to take it to a gunsmith to make it heavier...