I don't use either (bullet or carbo). Harken Micro Blocks.

It's important to use square (not hex) nuts to secure the bracket. They will grip the inside of the track, whereas the hex nuts don't.

Even so, I still had a problem with the bracket working up the mast. Used a file to make a flat spot for it (and create a bit of a "ledge" at the top) fixed that problem.

The upper end uses an old tiller extension connector/bolt to replace the ring/pin that holds the gooseneck together. Otherwise, you'll shear the cotter pin right off.