Are self contained Artillery shells that size bottlenecked and rimless? The ones I have seen were rimmed and straight.
There is no need for any big gun to be rimless, but there are many, many bottle-necked cases.
US 37mm, M74 AP (M3, 37mm cannon)
There is also the very similar 37mm that went with the automatic cannon, M1, that was semi-rimmed.
A few examples: left - Soviet 130mm AK130, right - US 3in Mk 9
From lt to rt:
5 cm KwK 39 HE (Pzkpfw III)
7.5 cm KwK 37 HE (Pzkpfw IV, short barrel)
7.5 cm KwK 40 HE (Pzkpfw IV long barrel)
7.5 cm KwK 42 APCBC (Pzkpfw V, Panther)
8.8 cm KwK 36 HE (Pzkpfw Tiger)
8.8 cm KwK 43 HE (Pzkpfw Tiger Ausf B, aka King Tiger) (for reference this this is 0.8 meters long and 15 cm at the rim)
12.8 cm PaK 44 APCBC (Panzerjäger Tiger Ausf. B, aka Jagdtiger)
From lt to rt:
British 6 pounder, 7 cwt APDS (57mm)
U.S. 75mm M3 HE
British 17 pounder APDS (76.2mm)
British 77mm APCBC