Hello everyone.

I've been following the community for many years and have built a few models thanks to the superb information provided by everyone.

I know this topic keeps coming up especially for non-American makers.

I'm familiar with ECM, I've done the FGC-9 and it turned out very well. I've tried the .22 rifling button from the guy in Ukraine with dubious results (I've NEVER seen rifling buttons on AliExpress). I can see the marks, but I'm not certain they're deep enough. This was for a Harlot build. I then did a .22 barrel for the Dirty Harry build using ECM with mandrels in the Professional Damage ECM Pack. I think that turned out quite well and was surprisingly easy.

I've used 12 mm OD 5.5 mm ID hydraulic pipe from AliExpress which seem to be readily available, but I was trying to find a suitable pipe with a smaller OD.

The best source I've seen is McMaster which carries a 3/8 inch, 0.216" ID which is rated for 15000 psi which seems perfect, but it's like 80 bucks a foot and I haven't even looked at shipping outside America.

I have not found any pipe on AliExpress with a 5.5 mm ID less than 12 mm. I usually look for 42crmo or 'explosion proof' in the description.

I do have access to a small lathe. How safe would it be to turn down 12x5.5 explosion-proof tube to say 8 mm OD for a .22 barrel? Would it support the pressure?

TIA