I got a set at a clearing sale, some one said that's a bit of a waist of cash(I hadn't used them before), they cost me $NZ 5, they get regular use, and I wouldn't be without them.
With the end telescoped out a little larger than the bore, put it in the hole at an angle, straighten it up, there by pushing the end in as you rock it, tighten and remove at an angle. ( I know what I mean)
Ian S C