25 Pounder info needed.

[david moore]

David is right - it's almost certainly magnesium - aluminum would not flame - despite the misinformation put about by the steel industry after the Falklands war that Brit aluminum ships burned because of aluminum use!
Aircraft wheels were almost always magnesium in the war - a lot made in the Alcan plant in Kingston, Ontario. That could be exciting if a tire burst. Magnesium casts very nicely but is extremely difficult to make into sheet. There was a lot of magnesium capacity in the war and it was used wherever possible to replace valuable aluminum.
If it does set alight, do not use water on a magnesium fire - it makes it worse! Have to use sand as per the ARP instructions re (magnesium) incendiary bombs!