The earliest Darne catalog in my possession is 1909, and there are no Halifax version guns listed. Unless it was the NRA museum, or the museum in Leige, I'd be suspicious of a date of production of a Darne a museum was displaying, based on serial numbers. Halifax Darnes were the field implement of the Darne sliding breech design, with production that ebbed and flowed with the condition of the European economy. If there was an attempt to keep historical records as to production of Halifax guns at the Darne company, I'm not aware of it. Serial numbers are not that useful for dating Darne guns. I can go by when the guns showed up in the catalog, and that is about it.
Did you post a picture of the gun at one time? It seems I noted proof with French smokeless powder T, which puts production at year 1900 or later, since the proofhouse started using powder T in 1900. I would have needed a picture or description to get you that.
If you email pictures to me, I can post them for you. Click on my name in the post to get to my profile, and, email address.
Best,
Ted
