General reply -
I picked up my swaging pliers from Carl Shoup at a VSC a few years ago. Excellent, for the sizes of lines that suit it!
Carl stressed that technique is important. It is not a one squeeze job. Of course, the copper tubes must be deburred, first - twirling a #11 blade inside to shave a slight chamfer works well.
Then, when you have the length, eyelet and lines set up correctly, Carl recommends taking at least a dozen squeezes, from different positions around the copper tube to draw the 'crimp ferrule' you'e creating down evenly, centered and straight. Actually, I think he said more like 50 separate, small presses. It's a thing to do until it's done right, not until you count to any arbitrary number.