Thanks for the info all. I am still studying this situation as I only get one shot at this hole and it needs to be within a few thou!
So I did a bit of experimentation over the weekend and not unlike Sp01's example I thought I may be able to center and drill from the back side. I found transfer punch I had, a cheap one from Harbor Freight, but it fit the spring recess nicely to hopefully ding in a dimple for a drill start. Well, I hit it pretty good a couple of times and it did not phase that stainless slide. It must be pretty hard sturff!!! Some stainless alloys can be that way and do require a carbide tool at proper speed. Very difficult to work with.
Perhaps Schmeck Head can elaborate on that experience.
Tonite I did find a drill guide from a screw extractor set I had that should go in the spring recess hole nicely. It is made for a 3/16 drill which should be also fine for a long #12 drill I have. I may throw it in there just to see if it will cut the stainless.
As the recess was milled out, there also seems to be a raised tit at the bottom! This may need to be ground out with a dremel before I can even start a regular HS drill.
Long story made short, if I cannot make some progress here I may just know my limits and hold off till I can have it done by proper equipment rather than pissing off "the Queen" which cost a LOT to Bling!