Time or two I've mentioned using Blue Wonder gun cleaner to take off rust. Other day at the flea market I picked up a couple of saws, one to clean up and use, the other to turn into scrapers, and thought this would be a good tryout/demonstration of the stuff. Here's saw this morning:No, wasn't that bad when I got it. I listened to the weather for last night and left it in the back of the truck. Where that 'extremely slight chance' turned into just enough light rain to cause rust. So, dribbled a little Blue Wonder on and started scrubbing with 0000 steel wool, and a couple of minutes got this:
It stripped off all the surface rust very well. I've used it on guns a number of times, and- like the label says- used right, it won't damage bluing.
By the way, if you've not heard of it, the best thing I know of for a saw is to clean it, then give it a coat of paste wax, like Johnson's Furniture Polish; it'll protect the metal from rust, and helps the blade slide through wood.