Remove the butt plate. There will be a hole. There should be a slotted screw at the bottom of the hole. Use a long screwdriver and be careful to not damage the stock.
The value of a 1905 model D single barrel choke bored Diamond Arms shotgun is actually dependent upon a number of things. Most importantly the condition of the shotgun.
50-100 USD
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$35-$75, depending on condition.
No published sn data available.
i saw one in 90% condition sell for $150.
$35-$90, depending on condition.
About $50-$75 as a mantle decoration.
Single shot: $25 to $75, Double barrel: $100-$200, depending on condition.
It will be around 65 dollars for this pin. This is an easy fix to get your shotgun working well again.
Some models of Diamond Arms were made by the Crescent Fire Arms Company for the Shapleigh Hardware Company of St, Louis, Mo. between 1982 and about 1922.
Diamond Arms shotguns were made by several manufacturers, but if the rest of the patent date is '13', this one was by J. Stevens Arms and retailed by Shapleigh Hardware.