I have some from the 1800s to now and use them in all sorts of machines from treadles to electrics, plastic, cardboard and metal. Doesn't matter if it's a 66, 15 or L(or M, can't remember which one it takes). I have an industrial shuttle bobbin and one from the era and a handful I have machined.
I have found that some work better then others regardless of age, material or country of origin and some won't work well in one machine, but work fine in another.
If they don't work well, I toss them in a jar and go on. They aren't so expensive I can't replace them.