Dave is actually right here for the most part, 1/6 scale is actual measurable thing, not as complicated as people seem to think. Hot toys MOS is a mistake plain an simple, he is to tall, just like dave said he scales in at about 6'6" tall. How can this be determined, well here's the easy way
average male is about 5'8" tall, but to make the math easy lets call it at 6 foot, that said 12 inches would be 6 foot tall in 1/6 scale so every 2 inches is 1 foot
The rock figure is 12 5/8 inches tall, that scales at 6'4 1/2 which is nearly perfect as the rock is actually 6'5
The MOS figure should be 12 3/16 inches tall to be 6'1 and he is not he is 13 inches tall which puts him at 6'6"
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Hot toys already had the scale correct for the most part, if they want to make there figures larger we can't stop them, but if they do they will no longer be making 1/6 scale figures, MOS is not true 1/6 scale, its not 1/5 scale ether, its a plain an simple mistake.