Measurements are taken from actual parts, are not based on original specifications, and apply to all models unless otherwise noted. Thread diameter and screw lengths are averages of several examples and vary among individual parts. The thread pattern on screws and other secondary parts appears to be the English 55 degree Whitworth pattern. However, the receiver and barrel are a 60 degree pattern according to Myron Petro of Aces & Eights Custom Guns and Clark Magnuson. Their assistance in measuring these is greatly appreciated. Russia bought the original tooling from England and the M91 was built to an inch pattern as the metric system wasn't adopted until after the Revolution. All subsequent Mosins maintained the same patterns and therefore screws from the earliest M91s will fit the last M44s and vice versa. All thumbnails and full size pictures are to the same scale with each other. The simplicity of the Mosin Nagant design is illustrated by the fact that there are only 5 different thread sizes out of 11 threaded parts on a typical Russian/Soviet model.