1876 Winchester barrel markings|General Discussions & Questions|Forum|Winchester Collector

Bert, I had to remove magazine from my 1876 45-75 Winchester which enabled me to see nos. on barrel bottom. My letter says received in warehouse Sept 13, 1878. On the one flat under forearm is 776, a no. 2 appears next to the breech on bottom (which is not flat but concave). There is also a C stamped cross-wise to the barrel and 2 Cs stamped lengthwise with barrel. I can imagine my barrel was made in 77 but why 776? Also, what is signifigant about the Cs? My letter says originally fitted with set trigger but was removed at factory. The SN is 3267. Don