Very few, if any saw service in the ACW. There is a picture of Birge's Sharpshooters (a US Unit) that appears to have some being carried, but upon closer inspection they are not Hawkens. The Hawken has no place at any re-enactment that has standards. Those who carry them are usually quickly given the appelet "FARB" or worse: cowboy. Deserved or not the Hawkens and the "Zouve" both have garnered a place of shame in the community.
That feller in the Wilderness also had another nice thing to say about his Texicans, When one of the British war observers noted that some of the Texas Brigade had worn out the seat of their pants, that Virginia guy (who was a Texas land owner) said, "The Enemy never sees the back of my Texans."