I've used lots of different barrels through the years. My favorite by far is a DeadlyWind Carbon Fibur barrel (quiet and accurate). It uses Freak inserts. You can get a new one and a couple inserts for $100.
Whatever you choose, I recommend a barrel kit so you can size your paint to the barrel. Proper paint to bore matching helps consistency and accuracy.
Im pretty shure you can run a swab through it. I've looked at it online and it works the same way as the freak barrel kit I have, except that mine is a 2 peice barrle and the DW barrel is 1. (not counting the inserts)