Habu & Guys,
Well said, In addition to what Habu said, you will be much more pleased with the accomplishment if you actually make the swamp. It certainly is well worth the effort. Just don't try it with a fine cut finish file, use a big coarse cut file, half round is the best. Here is a before & after, really not as difficult as it may seem at first.
Even the imperfections you get by hand filing the barrel will add to the authenticity of your work. Give it a try, and be encouraged!
Jim