ive done a few and buggered up a few. i have a sight tool but it doesnt work on all barrels and was pricey. i usually use a brass punch and lump hammer. i like to put some weight behind the punch instead of tapping like 30 times with a lighter ball pein. i cover the barrel areas near by the sight with a couple layers of electrical tape just in case of slips. i also put a thin layer across the sight where the punch is going. even though its softer metal you can leaves some scars. i put the barrel sight laying over the center of a roll of duct tape so you can hammer through with nothing in the way and the sight falls out. when i re-install the site i take the round end of the ball pein hammer and tap the dovetail slot lightly a couple times to close the edge in just a hair so when you tap in the new sight its tight.