Barrel mounted sights require drilling and tapping in both locations unless the barrel comes with sights from H&R which some do. Or they can be ordered with sights in the acc barrel program, but they will charge an extra $50 or so if it's not a factory option. Rear aperture sights that fit the 2 rear scope base mounting holes are available. Williams makes front sight ramps that can me sweated(soldered) on, too. For more info on sights, see the FAQ.
Tim