Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I believe boring the fittings a hair bigger will be my only option. I have also checked industrial, scientific, and lab supply houses with no luck. I also thought of possibly making a longer 5 mm tube red hot to give it a stretch which ought to make it a little thinner. This might involve a learning curve so I'll likely bore out the fittings. Stuart Models doesn't even have it on their website unless I'm looking in the wrong places.
I have a couple new old stock Stuart tube's but they are for the 500 to 504 boilers hence to short for my needs. PM Research has 5 mm and the only thing Ministeam has are Jensen sized for 2.5" & 3" boilers.