Anyone notice the appearance of an 1880s Webley Army on The Walking Dead this week (episode 310, at the 21:25 mark)? The father of the latino family trapped on the bridge had one of the early models with a fluted cylinder, and with bird's eye ivory or wood grips.
Where is he finding ammo for that thing during a zombie apocalypse??
Funny I missed that but caught Glen's Aldens afterwards
But to your other part I'm guessing he was probably a horder awaiting the Mayan apocalypse and low and behold when zombies arrived instead he had all the ammo he needed.
Having not yet seen the episode I'm shooting in the dark , but maybe he finally ran out of rounds so he dropped it. Of course, with as much as they weighed he could have hung onto it to use as a club!