I always check my sling and swivels when I take the rifle out of the slip before going shooting (good dsc1 stuff) but I never thought to check the Chicago screws.
The top end of the sling gave way due to the screw coming apart and the rifle rotated round with me grabbing the butt until the moderator (T4) hit the ground, which was thankfully tussocky grass. I haven't been able to check zero yet but here's hoping all is ok. Maybe having an over barrel type mod gives more lateral strength in situations like this.
The moral is...if you use these screws then a bit of locktite is a good idea. It's difficult to get a good purchase to tighten these things though as one side is just rounded.
I'll be sticking to my "Uncle Mike's" sling with the buckles from now on though.