Yup, I had the same problem, except mine broke from overtightening. Just like his did. It just took some pressure to make it fail. The book says to turn it down till it touches the rear of the receiver. Do not tighten!
Anyways, so close to hunting season, I used a threaded insert then drilled and tapped the end of the receiver for a set screw, counter bored the threaded insert, and off to the woods I go.
I don't care how rigged it looks, my ass is going huntin'.