I prefer using a screw that I can't adjust with my hands, but that is just me.
What I also did to my TDC was add a nut on top of the hole and glued it in place with JB weld. Just make sure the glue does not touch the threads. I spot glued three dabs then once that dried I glued the rest with out the screw in it. This will give you TDC more strength because the barrel it self is thin and it will bend if hit while on field.You read my mind. I actually got a knob screw for it earlier today. I just need to drill and tap it and I'm golden.