Could be. I relied on Charles James' "Military Dictionary" (1810), (and George Nafziger's explanation to me with respect to that measure mentioned in "Imperial Bayonets") but I see that the Shorter Oxford English Dictionary indicates it to be as you suggest, 6 French feet, equivalent to 1.949 metres or 6 and 2/5ths English feet (or 6' 4.8")...making a 6.66% deviation from a 6-foot measure. All in all, for the purposes of measuring in the field, given that it was based entirely on eye and stride, such a difference is largely negligable. For me, this is reinforced on James' reliance upon the practical measure of 6 feet and the widespread stated equivalence to a fathom (a stretching of the arms to their full length [...which is, of course, likely to have been less than 6 actual feet 200 years ago!].