First, I am not a machinist (in any way shape or form).I would like to buy a set of metric taps and dies, hobby quality. The smaller common sizes is what I think I would use. Please, what sizes for airguns should I make sure the set includes? Any suggestions on a lower priced set you have experience with will be appreciated. I see a lot of sets online, Ebay, Amazon etc. The sets at MSC and McMaster Carr are too dear for my once in a while use. But I do believe I do not want carbon steel, I coud be wrong.