37MM Proof?

[Dunkbfg]

This came with a 1943 dated 37MM M16 case, but not necessarily mean't for it. Looks to be a proof, but usually they're not tapered.
Anyone able to ID better?

Thanks.

 

[ordnance]

Not a proof but a simplified target practice projectile made during WWII.

 

[RichardB]

Isn't it the 37mm M51 Practice....and would have been light blue in colour
So, the case would be correct

 

[Dunkbfg]

Thanks. Never seen one before. Also explains why it has a tracer cavity.

Duncan.