Sounds like you need to find some detailed reference material on the Trapdoor. I'm no expert but from what I glean from your description I'd be very wary.... i.e. there were no "original" .44-40s or 1878 models. Garry James wrote a piece about the 1879 Carbine that details a few of the differences between models. http://www.gunsandammo.com/historical/the-model-1879-springfield-trapdoor-carbine/

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Ancient order of the 1895 Winchester

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