All photos and information thanks to Andrew Edgcombe.

This is a base plate/gas check made by Precision Engineering Company, Wellington NZ.
Precision Engineering items are identified by the NPZ stamp.

*********************************************************

This is a Precision Engineering Company grenade lever.
Precision Engineering items are identified by the NPZ stamp.

*********************************************************

WHE filler plugs and center tubes (see below) were manufactured by William Henry Enstone (W.H.E.), an engineering workshop in Otahuh, south of Auckland.
In the early stages of WW2 he designed and manufactured grenade center tubes and filler plugs, the filler plugs were "square drive" and made from zinc.
Many NZ made grenades are found with WHE furniture.

*********************************************************

Base plugs :

Shown below on the left is an "MP" (Mason & Porter) cast iron base plug.

The zinc base plug on the right is marked "PDL".

Both types are common on NZ Mills Bombs.

*********************************************************