Hi crshelton,
Thank you for posting the info from the 2nd edition of this book.

It's interesting to note that the author has reduced the claimed proof pressure which was printed in the 1st edition by a large amount.
1st edition-32,000+psi.
2nd edition-13,000+psi.

That's a step in the right direction.

However, when calculating the force against the breech, he has still made the same mistake as in the 1st edition.

He has again used the case head DIAMETER when he should have used case head AREA in square inches. {.515 sq in}

His 2nd edition (incorrect) calculation using case head DIAMETER of breech thrust resulted in 10,530 pounds force against the breech.

Using case head area, would result in the considerably lower figure of 6,695 pounds force against the breech.

His figure of 10,530 is approx 50% higher than 6,695!

As I mentioned before, despite the math errors concerning proof pressures and breech thrust calculations, the book does contain some very good ideas on how a shotgun to double rifle conversion can be done.

Cheers
4seventy