Hello Itai! It's not a .50 cal, it's too small. Please see this other image I've posted.
7 is the mystery bullet above, and A and B are your garden variety Japanese 7.7mm and British .303 respectively. They're about the same size, and if 7 were a .50 cal you'd expect it to be maybe twice or three times the size.
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I think this is an American …
I think this is an American .50 caliber. I have found a couple in Tai Tam
Too small
Hello Itai! It's not a .50 cal, it's too small. Please see this other image I've posted.
7 is the mystery bullet above, and A and B are your garden variety Japanese 7.7mm and British .303 respectively. They're about the same size, and if 7 were a .50 cal you'd expect it to be maybe twice or three times the size.