I didn’t find anything about this specific topic in the threads the search brough up, and figured a forum member somewhere would probably know the answer to this question. I’m building the 1/32 scale Hasegawa P-47 and would like to substitute metal tubing for the plastic 50 cal guns that come with the kit. I understand hypodermic needles are one source of materials, and I see brass tubing for sale in the Micro-Mark catalog, but I don’t know what size I’m looking for. Is there a handy-dandy conversion chart out there in modeling world that lists which tubing size to use for various sized guns at different popular scales?