I just drilled a 9/64 hole into 1/8 piece of hard steel and drove a 1/8x 3/8 u tyoe drive screw into it to test the holdign power. It will never come out that I can see. I will use the 1/8 X1/4 to build for real. Wow! what a hold it has on that steel.
I am sorry to say that after some further experimenting I have decided not to use the drive screws to build with. I am not so sure they will hold as well as I first thought. My original motive was the same as most, tryingto avoid the barrel pin problem. I solved it in a way by simply drilling it out and replacing it. It is much easier and I stll have the good feeling of strength that mashing those rivets gives me.