Would a KE case go with an NWM break-up projectile?
Unless it is a very special load by NWM (Holland) it appears very odd that they have used Swedish cases.
The red O (onklaar) in the headstamp was used by the dutch military when they inerted a cartridge.
What type of projectile is it (should be mentionned after the marking 20mm xxxx)
The profile of your projectile looks to suggest 20x102 to me…
If it is an MU10, it is ment for the 20x102.
For the 20x110 HS804 and 404 was MN12, and the MN13 for the 20x128
The NWM sales catalog does not say what cases were used, but i’m guessing they would have used NWM cases.