I've made brass scrapers from .223 shells--flatten them in the vise and scrape away. You can use larger cases, like the .25-06 if you want a larger "handle."

I soak in Kroil at least overnight, scrape and wipe off residue (you don't want the rust to form an abrasive paste and grind off your bluing), reapply kroil, repeat until satisfied.

I've also had good luck with the "big 45" stainless steel wool balls, particularly for larger projects like rusty old lever guns, shotguns, etc. that don't have a high collector value.

I use the steel wool dry, when a powder starts to form from the rust I stop, blow out the steel wool ball with a compressor, carefully clean off the rust dust, and start again. When I'm done for the day with that gun (2 or 3 scrubbings), I'll wipe it down a couple of times with kroil then leave it overnight, degrease and start again until I'm satisfied with it.

For your small patch of rust, I'd try soaking and scraping. Good luck!