The normal practice is to drill the screw out, but note that they are hard. Some gunsmiths anneal the screw by applying heat (soldering iron or torch with a small flame) but it is better to just use a hard drill. The 6x48 screw is pretty small to be drilled for an Easy-out, but I have done it. Usually, the trick is just to center the drill carefully, then drill the screw out so there is nothing left but the threads, which can be picked out.
Note that for that kind of thing, you NEED a strong, stiff drill press, with a heavy vise, and a short thick "starter" drill. Any normal length drill will wander and mess up the threads. You also need a bit of experience, so I agree with the advice to take it to a gunsmith. You might also consider having him redrill and retap the holes to take an 8x40 screw, a better choice especially for rifles having heavy recoil.
Jim