Indians For Guns

12C does have a relation with chamber length. 12C means the gun has a chamber length below and up to 2 3/4 inches. 12LC means the gun is chambered for 3 inches and above (Long Chamber). The 2 1/2 chambers were nitro proofed to 1 1/8 oz and 2 3/4 chambers to 1 1/4 oz. The Purdey gun in question is there for chambered for 2 1/2 in as per the nitro proof mark

Chengy wrote:12C does have a relation with chamber length. 12C means the gun has a chamber length below and up to 2 3/4 inches. 12LC means the gun is chambered for 3 inches and above (Long Chamber). The 2 1/2 chambers were nitro proofed to 1 1/8 oz and 2 3/4 chambers to 1 1/4 oz. The Purdey gun in question is there for chambered for 2 1/2 in as per the nitro proof mark

Well said. That 12C needs to be understood along with the rest of the marks. On its own, it does not tell the specifics one is looking for. To complicate things, there was also a 2" cartridge!

This is from the Birmingham Proof House for 1925, 1954 & 1989. 1904 through 1924 are same as 1925, except length of chamber is not marked. 2½" guns were marked 1 1/8oz & 2 3/4" guns were marked 1¼ oz. 3" or longer were marked with an LC under gauge in the diamond to indicate "Long Chamber".
Incidently the smaller the bore the higher the pressure walls of equal thickness will contain, or for the same pressure can have thinner walls. It is however, as mentioned, easier to load the 12ga to lower pressures than smaller bores, unless exceptionally light charges of shot are used. Many will load 1oz in the 12ga, but not many go down to 13/16oz in the 16ga which would be an equivelent load.

Is this gun still available for sale