Surface rust

The inside of my feeder has slight surface rust should I empty it and take care of it or will the rust not be a problem for the deer eating the corn

I don't think it's going to be a problem.

If its "really" rusty, then I would empty out the barrel and take a wire brush to it then paint the inside and outside of the barrel with "Rustoleum" enamel paint. If its not too rusty then just keep feeding corn this season and take care of the problem later. The rust won't be a problem for the deer until water gets in the barrel and the deer will have to eat moldy corn!

Shouldn't be a problem as they eat it with dirt when it falls on the ground. If you think its a big problem, or it looks like paprika sprinkled all over your corn then empty it and take a drill with a wire brush attached to it and go to town. lol

Wipe the rust down with phosphoric acid soaked rag then follow with dry rag. That will stop the rust. Let the rest dissipate for a few minutes and fill it with corn.

The rust wouldn't bother me too much. How it got there would though.

Surface rust is not a problem. Dry corn will prevent any major issues. I am in general more concerned with exterior rust. I take a spay can to the outside seams/lips every year or two just to keep water from collecting and allowing rust to start. Mine have been in service year round for more than fifteen years.