Nice catch on the non-matching serial numbers!
1957 was a chaotic year for C&H - diversification into non-gun products such as bird decoys and underwater gear, and "throughout this period the emphasis had shifted to the supply of surplus ex-Government rifles and equipment all of which had to be reconditioned, reproofed and tested at Acton." At the end of the year Interarms bought out the company's ordinary shares.
Apparently after WWII gunmaking became a sideline and C&H farmed some of it out to Birmingham. I know that there were quality control issues with some of the postwar Coggies, and the rough finish shown on the barrel undersides and action would make me doubly cautious about paying 6K for the gun at Cabela's.
