Given that my sole exposure to shotshells is when I buy pigeons from my butcher, these struck me as being out of the ordinary.
The caption to the photograph read; “Due to the inconsistency of commercial ammunition, proprietary shotgun ammunition was designed and produced. Notice that they are all high brass. The III marked shell contains 30 x steel BB, the IV contains 14 x ,22 calibre steel/tungsten and 3 x ,22 calibre tungsten/frangible. The V is loaded with 6 x Number 1 Buck steel and 3 x 00 Buck steel frangible. This ammunition is specifically designed for the AA12 and sold only to AA12 purchasers.”
A quick search turns up that they’re for the Atchisson Assault Shotgun, details here;
The article was in Small Arms Defence Journal and apart from the above there was a table that listed the cartridges including some not shewn in the picture. There are discrepancies between the two listings.
III 30 x Steel BB, 10 x Frangible Tungsten BB
IV 14 x .22 Steel/Tungsten, 3 x .32 Tungsten/Frangible
V 6 x No1 Buck Steel
VI 325 grain projectile, 26 x Steel/copper plated BBs (Projected range 300 yards, 14" of penetration in gel)
X 325 grain projectile, 26 x Steel/copper plated BBs (Projected range 300 yards, 14" of penetration in gel with explosive filler)
LTL 34 x ,23 Plastic balls (Less than lethal). (Non-lethal at > 50ft)