The Blish Lock was the result of observations made by John Bell Blish of large Naval guns. He noticed that guns firing relatively light charges tended to have their breech blocks unscrew and fly open. But the breech blocks of guns firing heavy charges remained closed. Using his mathematical and analytical training, he concluded that metals have a tendency to adhere to each other with a force much greater than friction, when subjected to very high pressure. This principle of metallic adhesion has since come to be known as the Blish Principle. It didn't take Blish very long to put this knowledge to use in a delayed Blowback breech lock. He developed a working model that used a simple wedge as the lock, and was eventually awarded a patent.
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