In my original post I stated �The older M77 triggers were adjustable for pull weight and over-travel, a feature that was dropped in the MKII triggers.� This is correct but incomplete and I�m surprised no one caught it. The older M77 triggers were also adjustable for engagement depth, which is felt as creep.
Last night I reworked two M77 triggers I had worked on a number of years ago, my 7mm RM and .257 Roberts. The Roberts came back from Ruger earlier this year and, while it seemed the trigger had been untouched, I wanted to check it out anyway. In doing so I realized what I had been working with in the past was pull weight and engagement depth. There was what looked like an over-travel adjustment screw but I didn�t understand how it worked as it would only screw in to a certain depth and stop long before the trigger contacted it. The last time I had worked on M77 triggers was early 2007, shortly after I purchased a used M77 in .30-06, and clearly my memory didn�t retain much. The written procedure I grabbed off the internet years ago and keep on my reloading bench didn�t mention the over-travel adjustment so it wasn�t a help, either.
At that point I decided it was time to look up the online Ruger manual and review the illustrated parts breakdown. In doing so I re-discovered something I had long forgotten - there are two screws that work together to set over-travel (parts D-44 and D-45 for my 1982 M77). The second screw (D-45) is in the trigger and while it looks like the end of the sear engagement screw, it is separate. The forward screw (D-44) is in the trigger housing. It gets removed to allow access to the second screw through the resulting through-hole in the trigger housing. After adjusting the second screw the first screw is replaced. I didn�t mess with over-travel on either rifle. I�ve got an 1984 M77 in .30-06 I might work on tonight and see just how well the over-travel adjustment works.
It had been several years since I had worked on a M77 trigger and I had forgotten how much simpler the MKII and newer Hawkeye LC6 triggers are. On the M77 the safety shaft has to be removed to get the trigger out and that means removing 5 parts by itself (safety button, connector rod, retaining clip, spring and shaft). Then there is a little thing called the trigger return spring seat that you don�t want to lose. Probably not a job you want to take on while working on a floor covered by shag carpet�
The M77 triggers I worked on last night had been worked on before and both were already much improved over the way they came from the factory. I cleaned the parts, put a higher luster polish on the mating surfaces (one in particular still had remnants of the factory tool marks), reapplied a bit of Teflon grease in the appropriate areas and reassembled the rifles. The triggers were compared to a couple of MKII and Hawkeye triggers before and after the work. Improvement on both rifles was slight as both were pretty good to start with - smooth but a little heavier than the triggers I was comparing them to. After the work both were perceptibly lighter and I judged the effort well worth the time spent.
