Inspired by the current issue of American Gunsmith, I decided to add a trigger overtravel adjust on my Marlin 60's. This was done in a matter of minutes with minimum special tooling.
You will need: Drill, tap (I used 6-32) with correct drill bit, caliper (precision ruler would work), flat screwdriver set, small allen wrench and a Dremel. Only part you need is a small allen set screw (I used 6-32x1/2)
(EDIT) There are a series of pictures that go along with this. For some reason they will show up in the text correctly on some computers and not on others. If you are not seeing the pictures, they are in this http://thefirearmsforum.com/album.php?albumid=482
album (in reverse order).
***UNLOAD AND CHECK CLEAR***
Remove trigger assy and drill hole right behind trigger.
Tap the hole (insert dirty joke here)
Reinstall trigger assy and thread in the screw until it almost touches trigger. Insert a "snap cap" in the chamber. While holding steady pull pressure on the trigger, slowly back the set screw out until the hammer drops. Back out another 1/4 turn. Measure how much excess protrudes out.
Take the set screw out and cut that much off of the front side (plus a hair more so it will set slightly below flush when complete). Slightly round the end you just cut and spot paint or blue the freshly cut end. Reinstall with blue LocTite and again run it in until it almost touches trigger then with steady rearward pressure on the trigger, back the set screw out until the hammer drops then back out another 1/4 turn.
If done correctly, the set screw will be just below flush when you are all done. Let LocTite set up and go shoot!