My $.02: As mentioned above, 12920 likely was numbered in 1863. The label is definitely 1856-59. The building on the label is 502 Oxford street. This label was adopted in 1848 after the Reillys' move to Oxford Street.
The label has two medals, the 1851 London Crystal Palace exposition and the 1855 Paris Universelle exposition. These labels appeared shortly after the end of the Paris exposition, late 1855 or early 1856 and lasted until the firm's name change from Reilly to EM Reilly in very late 1858 or early 1859.
In addition this label normally should have "Fusils a Bascule" on the top ("center-break long guns" in French - inherited from Lafaucheaux's guns at the 1851 exposition) and "Improved Breech Loaders" indicating Reilly sold new breech loading guns such as Prince 1855 patent guns. The label, though, does not have "fusils a bascule" and thus might be a very early version of the 1856 label. Haven't seen this before and I have save about 8 examples.
The label is not a reproduction; it could have been salvaged and put on the case at some point when/if the case was re-lined - the case does look to be in remarkable shape - or the case is not original with the gun. Whatever, it's a great case, great label and great gun.
Last edited by Argo44; 05/31/18 02:32 PM.