37mm projectile ID help

[mdot633]

Posted this on the projectile section...meant to put it here.
No idea on this one. Nose cap appears to be aluminum. Only marking I see is the patent number.

 

[Alpini]

nothing better than a patent number, it is from 1924 for a tracer fuze:

https://www.google.de/patents/US1518247?dq=1,518,247

(best click pdf download)

It would be interesting to see the tracer unscrewed. Good find!

 

[imaokie2000]

It's an American Armament TP-T.

http://www.bocn.co.uk/vbforum/threads/89927-37mm-American-Armament?highlight=american