As the Title Sayes, i would like to suggest that the 3,7 cm Sprgr.18 (on the Pz III Ausf.B and E) is replaced by the Sprgr.40 which was a new round (similar to how Pzgr.40 came) given out to Tanks and AT guns of 3,7 cm, as generally these guns and tanks often fired more HE rounds than AP rounds.
But why was the new round issued?
While the Sprgr.18 works, it was a 2 big chamber projectile, with 1 Chamber for the He filler (27g Pent filler) and one quite eaqually big chamber for the tracer alone.
As such this 0,635 kg round at 780m/s only had 27g Pent filler, with a long burning Tracer.
To increase the HE effect, the new Sprgr.40 was a redesigned round with much greater filling chamber and a small Tracer unit, expanding the filler to 45g Pent, with a full weight of 665g and still 780m/s.
This would in game double the effect of the 3,7 cm He round, and increase the damage zone, which currently feels quite lacking, often requiring multiple he rounds or a direct hit to kill.
(Still currently cant post pictures, so they will follow later on.)