Here's the layout
Compression Copper 3/8" tube with plastic ferrule
Compression 3/8" to 3/4" Adapter
Both nuts on the angle stop and adapter are pretty snug. However, if I turn the fitting, the copper tube is able to rotate 360 degrees. The fittings are not leaking. Is this correct or do I need to snug up the nuts even more till the tube itself is not able to move ?
Not a good idea to use nylon ferrules with copper tube. It will make a seal, but cannot have the mechanical strength of brass ferrules.