By it's serial number.
You need to tell us what model of what firearm. Auto Ordnance made a .45 cal semiauto carbine and a 1911A1 pistol.
By it's serial number. Go to: www.proofhouse.com
Proofhouse.com has Colt sn tables. You can also call Colt and they will tell you.
US Military weapons should be marked with the US Ordnance "Burning Bomb" mark. You might also check with the Auto Ordnance company for possible serial number traces. Submachineguns forums, such as subgun may also have some information on serial number ranges for the M1A1.
The Tell-Tale Parasol - 1911 was released on: USA: 14 November 1911
Guglielmo Tell - 1911 was released on: Germany: 22 July 1911 UK: 22 July 1911 France: 4 August 1911 Spain: 7 August 1911 USA: 21 December 1911
A good ordnance map will tell you.
In order to tell how old your Colt 25 semi auto pistol is, you will need to offer the serial number. This number gives you an idea of when the pistol was manufactured.
The cast of Guglielmo Tell - 1911 includes: Giuseppe Kashmann Bianca Lorenzoni
There is a date on the bottom
By the serial number.
Take out the back of it pull out the battery and it should tell you