Get all the metal off there, but before take note of any fit issues, ie take more off here, and there, you get the idea. Use a large but supple sanding surface, to make for a nice flowing surface without dips, and raised areas.
In around the lock , take care to get an even ridge all around there, can spend extra time to make it fancy there. 150 OR 180 grit, then get a few coats of tru oil, spray on rub in, small areas at a time work best cause it sets quick. Also a 75-85 degree room is nice for the finish part of the job.
After the gun wood dries out , light sand with 220 grit , and add more tru oil rubbing it in so it looks great. Around 8 to 10 coats work great. Can make it satin or gloss. A light coat inside is a good idea, barrel channel, and lock area etc.
Good luck , wood looks awesome !
A few tricks could range from raising the grain with a damp cloth, to applying the oil with the grain etc..