They make several different hook systems. The Target 4 has the release hook close against the body of the release to trap the loop and can be attached either before or after cocking the sear. I've used this one a lot with a loop and can't see how it would be possible for a loop to slip through unless some really skinny line was used for the loop, but no way with standard loop cord. (however, that's neither here nor there, maybe there was something out of whack with your particular release.) The Big Kid 3D hook totally encloses the loop and is attached by pushing the loop into a slot in the head of the release and then cocking the sear; absolutely impossible for a loop to slip off of any diameter (but the loop has to be sufficiently stiff to apply pressure on the back of the hook to get it to close before cocking it). The Ember is an open ended hook designed specifically for shooting with a loop; you just cock it, hook the loop and draw. You could dump the loop on this one if you cammed it far enough (similar to a BT release) as you drew it but it would take a serious screw up to do it (having the release upside down and all your fingers coming off the release except your index).