I am not too familiar with Rigbys or Crescent but from the pics here goes :
Firstly the fit and finish of the lock plates is decidedly rough, certainly not the product of a 'London' gunmaker.
Early Rigbys had a distinctive style of lockplate, with a kind of scalloped top edge, nothing like this one. Rigby lock plates normally showed the '7 pin' set-up quite clearly.
The action style and 'locking bolt' are something I have never seen on an English made gun. The fireing pins look like an accident waiting to happen

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The action body appears huge for a .410, note how the barrels are shaped to match the breech face and also the excessive wall thickness at the breech. At a guess I would say this might be a 20g frame to start with. The given weight is very heavy for an English .410.
The trigger guard is double the thickness of that in an English (hand finished) gun. The shape of it looks like an unfinished casting. Also the guard tang is unusual in that a long tang is the norm in English guns, at least in the higher quality ones. Also the guard has been colour cased, normally this would be blacked.
The safety slide is 'agricultural' at best and looks exactly like that on the Crescent 410 'Quail Special'.
The forearm shape is not English and the wood quality is 'firewood' by Rigby standards.
Apart from all that the gun looks exactly like the Crescent .410,(there are pics of this online at
http://books.google.co.uk/books?id=YqJb ... nt&f=false), Nothing like any Rigby I have ever seen.
Now the 'proof marks'.
These marks are not even close to London or Birmingham marks, not even a poor imitation.
Apart from that they are incomplete and totally contradictory.
For example the 'Not for Ball' inscription was used ONLY from 1875 to 1887.
The Nitro Proof Max mark was used from 1896 to 1904 ONLY. Note the abbreviation MAX was used not 'Maximum'.
There are many other marks that would be on a properly proofed English gun, and there is no sign of them on this one..
Apparently someone has used marks from two different periods and did not even do a good job on these.
The Rigby name and address is marked on the tubes, again most guns have that marked on the top rib. The address marked is 12 King Street, Rigbys were never there, they were at Number 32.
Probably I have missed something important but finally the Serial Number shown was used by Rigbys sometime between 1830 and 1835, and that is a loong time before this piece was produced.
870 Shooter, you got in before me but I spent too long on this story to change it now

We basically agree that its a pos.
I had not thought Spanish but thats possible even although bad Spanish is better than this.