Whoa, how vintage is that, I remember shooting that stuff not too awful long ago while hunting ducks in N/E Wisconsin, dang that makes me vintage so to speak. Actually it was in the early 60's, also used it for partridge, and rabbits, lots of heavy brush to clear back then. I do believe they were plastic even back then, but I could be wrong.
The latest photo's are of Winchester ammo 2 5/8" ammo the ones I thought you were referring to are Remington. That Winchester is probably late 1890-to 1920's.
If that's vintage, then so am I.
Nothing smells as good as a freshly fired paper hull shotgun shell...