“Make no bones about it” means nothing has been left to chance.
The “bones” of the expression refer to gambling dice, which for thousands of years were made of animal bone.
The oldest known dice were found in Iraq and date from 3000 BC.
Today, to make no bones about their honesty, the dice used in Las Vegas crap games are precisely calibrated and are manufactured to a tolerance of 0.0002 inches.
That’s less than one-seventeenth the width of a human hair.