Thanks for the help so far.
From the one example of a "waffenampt" I could find thru searching, I think that this is the stamp on here, so it looks like it is German.
The base of the shell measures 2 1/2 cm across. The length of the the shell is 13 1/2 cm. The top portion of the shell measures 2 cm across. The projectile is 8 1/2 cm long- 2 cm of that length fits into the shell- so overall when assembled it measures 20 cm in length.
The bottom of the shell has the waffenampt and under that a "W", some mark, an "A", an arrow pointing up and "88". Also "P414", "XIg" and "40".
The silver tip has "AZ5045" (I think), "R S 222 40 272" and again the waffenampt with "W" and "A" under it- can't read the numbers.
There are also four indents on the silver tip, two circular (very small) and two wedge shaped at the top.
It belonged to my grandfather, who was not in the military, but who I believe had a brother who did fight in WWII.