I recently bought a mini metal lathe. I'm making an airsoft gun on it, and i need to make a barrel. The particular gun I'm making is the ppsh-41 (for all of you guys that play cod5, you know what i'm talking about! and for those who don't know, it's pronounced peh-peh-sha), which requires a barrel length of 270mm (found from the blueprints). This is just under a foot, and about the max my lathe can handle (but mind you it can still handle it! ). For an airsoft barrel, the inner diameter should be 6.01mm (as BB's are 6 mm in diameter and you want a tight seal for max accuracy). How can i create a precision barrel like this? My plan for the most part is to take a brass tube with an ID slightly smaller than this, and put it on my metal lathe and then fine tune the inside. The only problem is is that i would need a 1 foot long (or i suppose 6 inch long if I go from both ends, but it might affect the bb where the 2 cuts meet at the center) cutting tool that's less than 5mm (leaving some room for error) in diameter, and won't flex pretty much at all along it's 1 foot length. Or does the flex part not matter because it would flex a consistent amount the whole way? Anyone ever do something like this before?