Is anyone aware of a conversion chart or other information that identifies the outside diameter for stainless steel tubing that can be used to replace 30 and 50 calibre and 20 and 30 mm gun barrels for 1/48th scale aircraft?

I recall seeing this information in a vendor's catalog many years ago, but that information is long gone. I have found several current vendor that offer stainless steel tubing for modelers, but have yet to find the conversion information.

Any help with this will be appreciated.

I think that I might have this info, somewhere. I will have a look and get back here. Please if I haven't posted in a couple of days do PM me (I am likely to forget )
Mal

Sorry Michael, so far I have drew a blank on finding this info, as it wasn't where I expected it to be DOH! I will keep looking
Mal

Well, I'm no aircraft expert, nor a micrometer user, but I did save this from another site when the question was asked a few years ago.

In 1/48 scale a .50 cal would be 201/2 gauge
A P-47 blast tube would be 20 gauge
A 37mm would be 18 gauge

for 1/72, or 35 you'll have to figure out the math.

Hope that helps