Copperhead tube artillery rounds are described on page 167 of TO:AUE and page 152 of TO:AR.
Main question is a clarification of intent: Copperhead rounds should function in all ways as Homing Arrow IV rounds, except that the Direct-Fire Ballistic damage on a successful hit is as listed in the table in TO:AR. Is this correct, or was the intent different? (Posting here to establish a permanent reference for conversation in Discord)
If so, suggested errata to be copy-pasted into the errata thread:
TO:AUE page 167: Change
"Copperhead Artillery munitions function as Arrow IV homing missiles (see p. 166), with all appropriate modifiers and rules applied. The base damage values for Copperhead rounds are listed in the Artillery Ordnance Table (see p. 152, TO: AR)."
to
"Copperhead Artillery munitions function exactly as Arrow IV homing missiles (see p. 166), except that the Direct-Fire Ballistic damage for a successful hit is as listed in the Artillery Ordnance Table (see p. 152, TO: AR)."
You could also have it reference the ammunition table in the back of TO:AUE (page 224-226) instead of the table in TO:AR to avoid the damage values being in a completely different book.