RE: Rem. 7600 Question
Short answer...NO, you can't.
The Accu-Trigger is the proprietary trigger for Savage bolt-action rifles. The only rifle that has, or can have an Accu-Trigger is a Savage, and all Accu-Triggers come installed on the rifle from the factory and are not available as an aftermarket upgrade.
That said, you CAN have the stock trigger worked on by a gunsmith to make it lighter and feel better, but being what it is, it's unlikely that you will be able to get it to feel as light or crisp as you could a bolt-action's trigger. That's just a drawback to pump-action and semi-auto trigger systems. To make them work safely they must be more complicated. More complicated means more weight, creep and overtravel than can safely be had with the simpler bolt action trigger system.
Mike