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You can buy a Colt Archive letter which will detail everything Colt knowns about the gun when it was shipped........

Archive Services - Colt's Manufacturing LLC

ARCHIVE SERVICES Preserve Your Colt’s History The Colt Archive Letter Considered one of the most unique and prestigious services offered for Colt firearms, the Archive Letter is universally recognized as an unparalleled investment in firearms collecting. These Colt Historians will search through...

www.colt.com

If the gun is chambered for the .38-200 (also known as the .38 S&W, and called the .38 New Police by Colt) a .38 Special cartridge will not chamber in it.

Note that after WWII a lot of S&W Victory Model revolvers chambered in .38-200 and given to Britain were brought back to the US and many were rechambered to .38 Special.
These were usually not very accurate and often split cases, but were safe to fire.
It's not unheard of for Colt's to have been also rechambered, although Colt Official Police models in 38-200 are not common revolvers.

 

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Gun Parts Corp sell good quality replicas of the swivel and the pin..........

Lanyard Swivel, Blued Steel, New Reproduction

COLT 1917, NEW SERVICE Lanyard Swivel, Blued Steel, New Reproduction

www.gunpartscorp.com