FWIW, Timney makes what they call a trigger upgrade kit that consists of a new sear and new spring. I've never installed that specific kit from Timney but Volquartsen used to make the same kit and I put one of those in a 77/17 and it made a HUGE difference. It cost a little more then just the spring only kit but I can just about promise you it'll be the best 55 bucks you can spend because not only does it lighten the trigger but it also gets rid of all that creep/pretravel which a spring only swap won't do. The difference is night and day!
www.midwayusa.com
Timney Sear Sear Spring Ruger 77/17, 77/22, 77/44, 77/50
This sear and spring kit will make an amazing difference in the feel of your rifle's trigger. You'll have a clean break of around 1.5 - 2 pounds. Takes...
www.midwayusa.com