1936 Edward VIII Shilling (10 Cents) East Africa Coin

Not many coins in England were minted for King Edward VIII (none in fact)
So I had to go look elsewhere to get a coin minted for him - From a British Colony of East Africa. (I was trying the find the West Africa Mule coin but no luck so far.)
So here is a 1936 a East Africa Edward VIII shilling (10 cents) with an 'H' mint mark. from the Heaton and Sons / The Mint Birmingham https://en.numista.com/catalogue/mint.php?id=18
which would make this coin a Bronze coin vs a Copper-nickel one of the same value.
The Bronze coin should weigh 10.9 grams and measure at 30.9 mm
the Copper-nickel one weighs in at 11.5 grams and measures in at 31 mm

So why would this bronze coin weigh more than its contemporary copper-nickel one?

This coin weighs in at 11.56 grams (close to the Copper-nickel one) and measures 30.9 mm (like the Bronze one)
The appearance is bronze even though it weighs more than the Copper-nickel coin. But seeing how this coin has the 'H' mint mark on it tells me it is from the Heaton and Sons / The Mint Birmingham mint and not the Kings Norton Metal Company, Birmingham, United Kingdom mint which would have a 'KN' mm on it.