It's name is simply "Reibzündschraube". It was used basically for the medium (17 cm) and heavy (25 cm) mortars (Minenwerfer) but also for the 24 cm "schwerer Ladungswerfer (Erhardt)". Maybe it was used for other mortars too (probably the 18 cm smooth bore mortar and not sure about the Flügelminenwerfer).
Factory-stamps for such things are almost unknown.
If the large one is called “Reibzündschraube”, what is the name of the small one?
(both are empty btw).
The small one was used for mostly obsolete german guns like the 9 cm Kanone C73/88 etc.
Yes, the small "Reibzündschraube" (not "Reisszündschraube") was used in guns with "Central primer hole" only. This central primer hole was in the center of the closed breech block. The different 9 cm guns had no central primer hole but an ignition hole on the upper side of the barrel and used the "Feldschlagröhre". I think the "Feldschlagröhre" was inserted directly into the opened breechblock from the upper side and pulled by a cord/wire through the ignition hole but I am not sure about it. Clarification would be much appreciated.
Do you know for which type of gun it was used?