Trapdoor barrel thread?

[Patrick Chadwick]

Can someone please give me the dimensions of the barrel shank on a Trapdoor?

I know it's supposed to be in the book "Single shot rifles and actions", but I haven't got the book and although it's also available online, there seems to be a geographical block preventing me reading it here in Mauserland.

Information

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[wjw]

Thread is 10 square threads per inch, Barrel shank length 1.433 inches with 0.875 inches threaded, Major thread diameter 0.900 inches, minor diameter 0.850 inches - barrel diameter nominal 1.0 inches

[Patrick Chadwick]

Many thanks! I wonder, why was there a fashion for square threads in the 19th C., as they are a PITA to cut, especially internally?

[Dick Hosmer]

My guess would be that they may have been considered to be stronger.