Mortimer is a name also recorded in the address of fishing tackle and sporting goods stores, past and present,located in Scotland.
The fact that your gun is stamped with a 7 suggests to me that is one of a batch of guns, made in Birmingham for the retail trade.These guns were engraved with the sellers name;in this case, my opinion is; R.S.Mortimer? The 7 is a typical control number applied by the actual Birmingham maker in order to to identify the parts belonging to a specific gun within the production batch[ie; parts in this era were not interchangeable].
The 13 would be the bore size at time of proof testing.
As suggested by others, another possibility is of course that it is a spurious gun trying to take advantage of the well known Mortimer name.It is worthy of note that records show that at a much earlier time[ie; prior to the date that your gun was made] a Richard Mortimer was active in the London gun trade. In the past I have encountered Birmingham guns marked with the name of a long dead maker.
Details of the proof marks would assist in confirming the origin of the gun.

Last edited by Roy Hebbes; 06/09/10 08:14 PM.

Roy Hebbes