It's possible that because this is a safety feature they intentionally rendered it undefeatable for liability reasons. Call Ruger and ask if they made it permanent? If you have to drill it out you may be able to drill it out a little bigger part of the way, tap the rest, then substitute a shoulder screw for the pin.
Before you go to drilling, get a plastic hammer with a fairly solid head and strike the frame near the barrel threads (where it is solid) and in the same direction as if you were driving a parallel pin into place. This may back the troublesome pin out.
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