Anybody know what these are?

[Noel]

Found these on the local beach recently. Although I have seen them before always wandered what they are. The particular part of the beach where I found them is next door to a military firing range (nothing much bigger than assault rifles etc) and I think they do the odd running about and hiding thing too so assume they are left behind from sort of army activity. First thought was part of a flare, maybe with a parachute? Part of a sand yacht (which often race in the area) also came to mind but unlikely.
Seem to be solid aluminium with a band of copper below the black rubber material and some sort of firing pin indentation in the base.
About 90mm long and 35mm wide:

 

[NazNomad]

Practice rounds... scroll about 2/3 of the way down this page http://www.prc68.com/I/40mm.shtml

 

[adidat]

Pretty sure there training rifle grenades

Adidat

 

[adidat]

Wot he said ^^^

 

[Noel]

Thanks Naz and Ad. Much appreciated.