If your gun is marked W. Richards (not Westley Richards) there are two possibilites I am aware of. The most numerous W. Richards guns are inexpensive Belgium knockoffs trying to take advantage of Westley's good reputation. But those should have typical Belgium proof marks which is not what you are describing. The other possibility is the gun was made by W. Richards another known English maker but this is also not Westley. The tomahawks may be the crossed Halberds which is the mark of the Birmingham Proof house versus the London house of Westley Richards. If this is the case you should have a reasonably well made gun. The 11 on the barrels is probably the actual bore size. There should be a 10 over c inside a small diamond indicating the size cartridge the gun is intended to fire. The gun was probably made after 1887 and before 1904 when the Birmingham proof mark became a Crown over BP. I am still figuring out the British marks so hopefully someone more knowledgable can make corrections where I missed.