Once a year. Unless you get caught out in a rain storm or hunt in particulary dusty/sandy areas which may require a little more maintenance. the spring can get gunked up, when i take mine apart I just soak it in Ronson Lighter fluid for 30 minutes then blow it dry with a little compressed air (not from a compressor, the canned air for cleaning keyboards). I usually do the triger the same way at the same time. This usually occurs after hunting season before I put them up for the winter.