Back then, we shot what we could get locally. C&H, then Meteor (Scotland) were mostly, used, but GO and Dupont was also available, then GOEX. Talking 70's to 80's here.
We shot quite well with it.
Even with slugs. That was when I had the 38" twist Bauska barrel on a stock & with apertures, was shooting inch 5-shot groups at 100yards off bags. Not further, though.
In around '75, Taylor and I used to launch round balls at a 14" white rock sticking out of black dirt on the "face" of the Chief(mountain woth an almost straight wall up and down).
The actual range to the rock was 325yards, according to my long, rangefinder. We hit it more often than not, even with my wife's .36 Seneca, but shooting the 128gr. Maxiballs.
I guess we didn't realize a round ball gun couldn't shoot that far.