I would like to suggest to give the 3,7 cm H-Pzgr L´Spur HVAP/APCR round to 3,7 cm Flak (36,37,43 and 44) guns such as found on the Sd.Kfz 6/2 (really not needed here at 1.7, its just an example) Ostwind, Ostwind II and Flakpanzer 341 and perhaps future vehicles like the s.W.S mit 3,7 cm Flak 43.
Such H-Pzgr or Pzgr 40 is allready found in the german tree on the 15, 20 and 30 mm Flak guns, but not yet on the 37mm Flaks. In the russian tree the ZSU 37 at Br 3.7 also got such an APCR round and other nations have strong guns in the first place such as the 40mm Bofors L/60 and L/70 in the american, british, french, swedish, japanese, chinese tree wether it beeing licence build or developed upon guns with penetration ranges of 72mm to 96mm at 10m with full bore ammo which is good at angles unlike APCR
Starting allready in mid war germany was in dire need for more AT guns, so all AA guns were dual purpose, to fight against planes and tanks. As such Ap ammo was given and the Bk 37 was only loaded up with H-Pzgr,
but ground crews also got their hand on such ammo, recongnisable by the White Aluminium, Magnesium cap. It is allready found on planes with the Bk 37 such as the Ju 87 G-1 and G-2, the Hs 129 B-2 and Bf 110 G-2. As well as Flakpanzers were to follow tank collums and had to protect semselfs as well as fight back if no enemy plane was in sight.
The H-Pzgr L´Spur:
37mm 0,410 kg 1150-1170m/s and a penetration of 110-113mm at 10m
It could be added in a mixed belt of HVAP-T Aphe HVAP-T Aphe like on the 20mm guns or similar configurations.
A picture of a Replica:
Ap and Aphe rounds are colored black while HVAP rounds have a white Aluminium Head
In this picture is a 3,7 cm Flak 36 or 37 in an Dug in position Loaded with the visible white H-Pzgr ready to engage targets.
Overall used against enemy armor: