The difference between good enough and a better design. Yes all of those actions and many others held up just fine for BP pressure. There were some failures along the way. A better design can reduce the number of failures. When designing from scratch many decisions must be made along the way, most involving some type of comprise. The designers job is to come up with something strong enough, yet still economical to manufacture. It is not that the Sharpes, 1885 etc were bad designs, but improvements can be made.

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