I have messed with several rimfire "shotguns" over the years, mainly for pest control (Remington 510 and Win 61 in .22 shot) but also just because the guns had interesting actions or some value (Stevens "Maynard" Model 101 in .44 CF shot and Win Model 36 in 9mmRF shot).
The .22 shot ammo I have had was all marked #12. But the others were unmarked or the shot size marking had disappeared with age.
It makes sense to me that these little shotshells were loaded with fine shot, since they were mostly used to kill little pests at little ranges.
But were they available in other sizes than #12? The ".44 Shot" cases at least look like they could hold a useful load of shot a little larger than #12s....
