I would brown it if I was building a kit. I did the barrel on my Brown Bess last year with Birchwood Casey Plum Brown. Turned out great!!! You want to wet sand the barrel with fine sand paper, then polish with OOOO steel wool. Prep is critical. Put a dowel rod in a vise and slide the barrel onto this. Heat the barrel with a propane torch - just hot enough so that the plum brown sizzles when it touches. I made a swab out of an old cotton t-shirt and dipped it in the plum brown from a cup. Keep the flame moving. Put a coat on, let it cool, wash it down, then repeat. I put 15 coats on the Bess and it turned out a beautiful deep burgandy brown.