Agree especially in vintage original factory . I would have close to that in 16ga vintage factory I think less the slugs but mainly all winchester pheasant which I bought 20 or more boxes of years ago when I heard they were stopping production of the 16ga compression formed hull and also bought 3000 or more winchester wads to reload them later on
But like you say I have been shooting the 16ga and gathering since 1965
There is one place here that the shop closed I am going to say in 1980 that has that and more in 16ga and 28ga vintage shells. I have tried many times to buy the lot but of course the grandson that has them now thinks they are worth like 10X what they are
As far as modern 16ga shells canadian tire here stocks federals all the time
Cheers