In anticipation of shopping for a .45-70 Trapdoor, I've been studying Al Frasca's book but I'm having a problem correlating dates and serial numbers. The dates and serial numbers presented in Appendix F-2 (pg. 378) don't seem to match up with the text. For instance, in Section 5.8 (pg 74), the author states that longer, deeper gas ports were initiated in "early 1877" between s/n 77,387 and 77,670 and provides text from a supporting letter from J.G. Benton dated December 1876. The table in Appendix F-2, however, estimates that 1877 production encompassed serial numbers 74,216 through 76,727. So according to the table, the specific serial numbers cited wouldn't have been produced until 1878. I find this problem in other areas as well. 
Am I missing something here (highly possible)? Thanks.
Am I missing something here (highly possible)? Thanks.

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