How many have you had fail on you?
What are the specs (weight, cartridge, scope) and how many rounds you put through the rifle on which they failed?
I've got a few sets of them and with a little loctite and self-control when torquing down the cross slot screw have had no issue. I don't shoot a ton but more than the stereotypical deal you describe; in each of the two rifles I'm thinking of probably around 1k/yr?
