McGowen Precision Barrels v Proof Research, TTAB can no. 92067618 (precedential).

Petitioner seeks cancellation of Respondent’s registration for a configuration trademark:

a gun barrel trade dress registration described as:

The “mottled” appearance was created by wrapping carbon fiber around a gun barrel, “curing” the fiber, grinding it and polishing it. As carbon fiber is substituted for steel on barrels to decrease weight and provide other functional benefits, and this pattern is the resulting appearance of a particularly advantageous method of wrapping fiber on a barrel (and was patented as such), the pattern is functional and thus unregistrable as a trademark.

TTABlog discussion here.

Text of TTAB decision in McGowen v Proof Research