I have drilled over 50 of the wedges and there are 2 types, ones that have a small diameter at the base and some that are larger. the larger ones are glass hard all the way through and can be a bitch to drill. however with a sharp carbide bit, some tap magic and a little patience they will drill.
As for chinese drill bits they are made from old noodles, spend a few extra bucks and get some good US made ones, take care of them, use cutting fluid and they will last a long time. cheap cutting tools are for wood and plastic.