From The Truth About Guns: http://www.thetruthaboutguns.com/2016/02/robert-farago/how-to-bluere-blue-a-gun/
February 22, 2016
requent TTAG commenter Dyspeptic Gunsmith saw the gun above in our post A Garden Gun Cultivates a Newfound Fascination and answered reader questions about blueing/reblueing a gun thusly:
If the rust is very fine and there is still substantial blueing left on the gun, you might want to strip the blueing. Brownells has a product that will strip blueing and rust (Fe3O4 and Fe3O2, respectively) and not corrode the underlying steel. Remove the barrel & action from the stock. Remove the bolt & trigger group – this might require a pin punch on some guns to pull the trigger group. From what little I can see in the picture here . . .
it would appear these sights are drifted into dovetails. To remove them, you put the action/barrel into a sturdy vise (padded with soft jaws) and you use a piece of brass rod to drift the sights out. You’ll want to clamp on the barrel directly under the sight you’re about to drift out. They’ll usually go in from the right, and be drifted out from the left (ie, drifting them from left to the right as the muzzle is pointed away from you).
So basically, you’ll want the rifle in the vise with the muzzle pointed to your left. You should put the brass drift (which you can make out of a piece of brass rod about 1/4″ in diameter) on the sight base, and then start tapping the end of the drift with a small hammer. Before you start, it might do you well to mark the sight base on each side of the dovetail with a Sharpie marker, so you can see when the sight begins to move.
Continue reading at: http://www.thetruthaboutguns.com/2016/02/robert-farago/how-to-bluere-blue-a-gun/