Canton, buy a can of Kroil, this penatrating oil has been around for years and will enter a gap of 1,000,000 of an inch. I have used this product for years with very good results. It's in an orange and black painted can. It also makes a very good bore cleaner. Try it after you think you have cleaned the rifles bore. The patch will come out almost black!
The tiny drill bit and Easy-out is the way to go.