Originally Posted by 79pmooney

That's an aluminum frame, isn't it? There are limits to what the frame threads can take. (I might think about drilling out those holes and using longer high quality bolts and huts + lockwashers on the wheel side if it were my bike and I really wanted to ride fixed.)

You have probably already thought of this, but you have taken de-geaser (or strong detergent) and cleaned the surfaces of both the frame and the dropout mating surfaces I trust.

Ben