Valkyrie grenade

As you may or may not know..the Stg 42 AKA the Sturmgewher 42 was the first gun given the title "assault rifle"..by Hitler himself. Sturm meaning storm, loosely translated to assault for some reason. And gewher meaning rifle. Sooo..your Gewehr-Sprenggranate Model 30 is the "rifle-high explosive shell model 30.

[Nyles]

Interestingly, before that it was known as the MKb.42 (H), or Maschinen Karabiner. They didn't even abbreviate Karabiner the standard way.