If you have the right tools it is fairly easy to drill and tap a Mauser rifle receiver to accept scope bases. Larry Potterfield, CEO and Founder of MidwayUSA, demonstrates the process for drilling and tapping a receiver using only hand tools.
He begins by securing the receiver in a special drill and tap fixture made by Wheeler Engineering. A drill bushing is inserted into the fixture to ensure the hole is properly spaced. A bit of cutting oil is applied to speed up the process. Once the hole is drilled, the drill bushing is replaced with the tap bushing and the hole is tapped by hand. Remember to go slow during this part of the process, backing off the tap every quarter turn to prevent breaking the tap. Drilling and tapping a military rifle receiver isn't always easy, unless you're a gunsmith, so be careful.