http://www.ebay.com/itm/271654532285
This vintage hunting vest was made by the Gem Shirt Company of Dayton, Ohio in the 1910s. The Gem Shirt Co. was founded c.1888, and diversified into canvas hunting clothes in the early part of the 20th century, innovating the usage of lined waterproof game bags. They were a high end maker at the time, making their products from an excellent grade of cotton canvas duck. They ceased production by the 1920s.
This vest is their budget version, with sewn on buttons instead of changable ring-backed ones, and without the side adjusters or buckle back which other models featured.

Chest (pit to pit): 21″ (doubled = 42″)
Length (front): 22″
Length (rear): 19″

For other vests made by the Gem shirt company, see here and here