Froggy: Usually any T/C standard nipple wrench will work on rifles. YOu need a special, small barreled wrench to get the nipples off of the small revolvers. Go to the " Links" section at the top of the index page here, and look at the suppliers. Track of the Wolf has an online catalog where you can actually see a life sized image of the tool you are ordering. Just ask the people when you call in your order if that is the correct sized nipple wrench to use with your particular make and model of gun. They will make sure you order the correct tool.
I assume you worry about drifting your rear sight in its dove tail notch. You need a pice of brass rod, and a small hammer to do the drifting, so you don't mar the sights. You would do best to have a friend actually hold the gun for you in a cradle while you hit the sight and watch how far it moves in the dovetail slot. Always begin by making a witness mark across the sight base, and the barrel, so you can always return it to where it started. The mark on the sight gives you an indicator for how much movement you have per hammer blow, too. Remember that you move the rear sight in the direction you want the ball to go. I always recommend looking closely at both the rear AND front sights, before moving either. Sometimes one or the other is clearly off to one side. That is the one to move first. With the front sight, you move the sight in the direction in which is SHOT, to move the barrel the opposite direction to bring it back to your point of aim.(ie. If your gun is shooting groups to the right, and you want to move them back LEFT to center the target, drive the front sight to the right, or towards where it was shooting, to move the barrel back to the left.)