Brake line tube diameter question

I bought one of these aftermarket brass replacements for a 60 el camino i had that i updated with 69 chevelle disc brakes , and an S-10 master cylinder, never had a problem with it. Maybe you got a faulty one. The OEM GM ones are brass as well.
It might have been a bad one. I was just sharing my story to help people decide. The original one that I took off the car was cast and the one I picked up at the junkyard from the same G body Monte is cast. So that is one vote for ok and 1 vote for defect.