It looks as if the twists are flexible, and would elongate when inserted into the bore, taking its shape and size. This would exert minimal pressure on the bore and clean any residue. Maybe not for a gun barrel, but some kind of bore for sure.
Are the individual strands sharp? Maybe it is a bore maker or enlarger or smoother?
would guess they are used to lap inside diameters. It looks like if it were rotated clockwise with an electric drill, the diameter would reduce and the opposite would be true if run counterclockwise.
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