The correct nomenclature for this Luger is
"DWM 1915 Mortar Luger"...
(Because a short artillery piece is a mortar...broadly speaking...)
I know, it's lame...but the best I could come up with...
One of our members here posted pics of his shorty Arty some time back...Looked pretty much the same as this castrated Artillery...(This is the Simpson's)...