Hmm. May be I should have mentioned that
Roschmann is my take on ロシュマン. I don't know if it supposed to mean this
Roschmann or this
Roschmann, or may be it just some random name
Although, during the shooting training between Ririka and Marika, the guns are said to be as Rheinmetall and ArmaLite models (they trained with different beam guns in the novel)