Unknown .32 Rimfire Adaptor

Can anyone identify this .32 Rimfire adaptor?
I thought it was a .303 as all measurements fit except for the shoulder length.
Made from brass with a steel firing pin off-set to hit the rim.

Dimensions are:
Rim is 0.526". Rim thickness is 0.060". Base is 0.460". Mouth is 0.393".
Inside mouth to clear the rimfire is 0.323". Case length is 1.880" (48mm).
A .303 is approx 46.2mm to the end of the shoulder so much shorter.
Does it look home-made or factory made like a Marble? Difficult to say.

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