Be sure that all surfaces that make contact, like the sear to tumbler are smooth. No burrs or jagged bits on cast parts. Sear spring should ride smoothly on the sear bar. Inside of the bridal should be polished, along with the inside of the lockplate, where the tumbler rubs. The same goes where the mainspring rides on the tumbler. After polishing those parts, a small amount of oil will help everything move smoother.