i dont have any experience with "bed armor" but it sounds like paint on bed liner?. . . i had very good results painting my frame with duplicolor bedliner which sounds like a similar product. i had quite alot of scaly rust on my frame especialy the inside of the frame rails, after you remove any scale taht might be there rustoleum makes a product called rust-reformer in a small white platic jug, the stuff looks like polyurethane almost, you paint it on rusty metal and it seals it and turns it slightly black, in my experience this stuff works very very well IF you first remove all scale. After applying (generously) rust reformer and letting it dry i used the paint on bed liner, it looks very nice and seems to be very tough, no evidence of rust continuing... hope this helps