Rather than go the expensive and possibly ineffective route of drilling the barrel, consider a tried-and-true and less costly approach first: different grips and ammo.
And between the two, grips first -- the right ones can make a night-and-day difference in perceived recoil, even with stout loads, and in concert with the right round, can transform a snubby kicker into a fun gun to shoot.
Suggest one of the rubber offerings from Hogue or Pachmayr; Hogue's Tamer is a recent one that gets a lot of raves for those in your situation.