Being, swapping tips on Luger for this weapon? (6)
I believe the answer is:
mortar
'being swapping tips on luger for this weapon?' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
This is all the clue.
(Other definitions for mortar that I've seen before include "Gun; brick bonder" , "Masonry bond" , "Brick-joining material or short cannon" , "may be set into wall" , "Building adhesive" .)