So i got a reply last night from Gene from Performance Pcs
And then another reply early this morning
First off sorry your having difficulty.
Without having more information I can't say for sure of course but in general the fittings are much easier to hold to tolerances because they are CNC machined from brass so we can specify +/- 0.1mm. Tube on the other hand is extruded and extrusion is not nearly as precise--tolerances of +/- 10% are common for most tube brands, (including ours). The other less obvious issue between the two is the ease of measurement for quality control purposes. With a fitting it is very easy to pick a fitting out of the bin and accurately mic it. Tube is a lot harder to measure because of its flexibility and that is compounded because it is manufactured in very long, (300-500 meter) lengths. It is further complicated because there is no set industry wide compliance standards so some brands tend to run very slightly over, (like Primo) and others tend to run very slightly under. If we machine the fittings over sized to fit larger brands and over tolerance runs then they don't hold well enough on the smaller brands. So we machine to the stated size--3/4" tube is 19mm for example so we run the compression ring to 19.10mm so they are a good slip fit over 19mm tube but will still tighten down securely. If the choice is between a slightly tight/difficult fit or having a fitting leak...
All of the above does not mean that the fitting is for sure within spec--just that of the two items the tube is much more likely to be the issue. I am not placing blame on the excellent LRT brand--we manufacture a brand of tube also so I know how hard it is to keep it within reasonable tolerances. hard as we try It is also not impossible you got a fitting that is a little tight. Unlikely but not impossible.
It sounds odd I know, (and unintentionally condescending--sorry) but did you try good old fashioned spit? When I come across tube that is a bit tight usually some spit will help move things along. I would not recommend any lubricant other than spit because any oil based lubricant might attack the tubing over time and they have a tendency to congeal over time making it very difficult to remove the compression ring. I have used extra virgin olive oil before and it works but spit is better. I have also used paste wax, (aka car wax) and it also helps--just don't get carried away--apply a very small amount to the OUTSIDE ONLY of the tube, let it dry, then use a soft clean rag to wipe off the excess wax. If you have tube that is a little large you will find that it also has a tendency to want to spin as your tightening the compression ring. You can counter this by grasping the tube above the fitting with your free hand to hold it in place until it has clenched down onto the barb enough for friction to hold it in place.
I hope this is at least a little helpful. Please let me know if you have any other questions.
So it seems as if i'm stuck and will try to make some headway with what i have here, but honestly it's prob the last time i shop there.
Gene couldn't have put it any more concise than that -- manufacturing tolerances are always more "loose" with tubing. Primo seems to always run kind of large too, so I'm not surprised you're having issues. It's still the "right" size as it's 1/2-3/4 tubing, but will be a little different each time. We actually get emails once in a while from customers blaming us for pulling the "wrong tubing" when it's, in fact, correct.
I checked a current roll, and collar fit fine.