The Revelation 120 was sold by Western Auto and is basically a Marlin model 60. These rifles have a rather complicated action which is difficult at best when it has to be completely disassembled. A task definitely best left to experienced gunsmiths.
The kink described here is one I have used on two occasions to make repairs without having to completely disassemble the action.
The problem is where the sear spring (see Brownells schematic number 285, item code #43) has the long straight leg broken where it fails to maintain tension on the sear. The sear spring is on the sear pivot pin and cannot be removed without complete disassembly of the action.
If there remains at least 1/4 inch of spring leg an additional pin can be installed to retain the shorter leg and provide tension on sear.
Tools and parts needed are:
Brownells roll pin kit (#080-518-000)
Correct dill bit for roll pin
Drill press or steady hand
Remove the action assembly and locate the sear pin. Remove any c-clips from either or both ends of the sear pin.
Select a location approx. 1/8 inch forward of the sear pin and at least 1/16th from edge of action sideplate. Then using the correctly sized drill for a 1/16th roll pin, long enough to reach through each side plate, and drill hole through both sides.
Deburr holes and clean any chips from the action. Position the sear spring properly to apply tension on sear and put the broken leg under the pin inserted through the newly drilled hole.
The newly inserted pin will restrain the spring leg and consistently apply pressure to sear.
Reinstall c-clips and reassemble rifle.
Check all work and safety check and test fire rifle.