Peter it all depends on the quality of the fittings.
The ones I get as part of a large negotiated purchase are junk, I could tighten them up as much as possible and they are still loose. Usually they have a "Made in Mexico" label
On the other hand when I do T&M jobs and order small quantities I get top quality parts. Compression fittings with deep throats and glands that grab.
I guess it all about what your willing to pay for.
Bob
