Data by loslau :
Total length : 76,5mm
Diameter : 51mm
Weight with fuze : 450g
Weight of body : 305g.
Charge : 40g black powder
Fuze : wz. AC23 , fuze hole : 11mm
Delay time - 4 seconds

Photo on the right © Greg.

Photos below and right © Loslau.

These are two KC grenades with slight differences.
Both fitted with the correct AC23 fuze.

AC 23 :