I'm thinking of weeding out any non-Coopers bottles. I usually bottle in glass, but for the swaps I've bought 4 cartons of Coopers PETs. If I can identify the ring-ins, I'll discard them. Hang the expense.
On another note, talking of crap bottles - a few years ago we were bottling our 1 litre evoo (extra virgin olive oil) in glass bottles, bought from a well known packaging supplier in Brisbane. That sized bottle was square, but with well rounded corners, and a lovely looking bottle. Well, we had two instances where the filled bottles were delivered to end users (friends, luckily) where the bottles soon after just exploded!
I got hold of one of the fragments from a "corner", and was astounded to measure the thickness of glass on one side at less than 0.9mm, while just around the corner, it was greater than 3mm! Obviously a faulty blow injection whatzit, but the end result was we could no longer afford to use them. So we changed our one litre packaging to tin cans.
However - I approached the supplier with the evidence, and was somewhat stunned at the response. Saying I must have over-filled them (I didn't), or mis-handled them (they weren't), or subjected to out-of-normal temperatures/pressures/cosmic rays, etc, (which as far as I know they weren't), he then wheeled out a trolley-load of documentation from the manufacturer quoting approvals, standards, world's-best-practice, stringent quality control, government checks, blah blah blah, trying to convince me that what had happened, couldn't!
So in summary - shit happens! And I'm guessing that PET bottles are blow-moulded?
Picture of fragment:
View attachment 107095