[quote=@ClocktowerEchos]
<Snipped quote by rezay>

Still working on what exact trade goods Highwarren can even produce.

Also by the 1800's cavalry was on its way out as a primary fighting force or focus. Most armies had already made the move towards infantry and line battles. If you have that tech and the industrial capacity, focusing on cavalry would require something actively blocking the adoption of infantry focused tactics.
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Well, that's the thing, NJ doesn't have the industrial capacity. Not yet at least. When they do eventually have the industry, they'll probably be stuck with rifled musket-type small arms for a long time. Somewhere in the 1820s to early 50s is where NJ is at.
They'll have to re-develop the last century and a half of firearms design, helped along by old world technology to make it more like a few decades.
Then again, maybe cavalry won't be so big. It relies on a wealth of other industries that are very specialized, advanced knowledge of which is not likely to have survived the apocalypse— saddle making, etc. Strapping a horse to a cart is probably easier than an artisan making a saddle to ride one. I imagine when they do ride horses, they do so bareback.

*I'm not exaggerating when I call NJ an upstart shantytown. There's nothing there but fishermen and farmers (for now). All the iron they source from the ruins, salvaging rebar from old reinforced concrete and such. There are maybe 3 blacksmiths (as in specialists where that's their only job and they are masters) in the entire town. Not much industry to be waging war on something like a US Civil War scale. 

They have a handful of firearms from the old world (revolvers from bunker security forces), which is all I could think of helping along their weapons technology in the short term.

*Important to consider, how would they re-invent smokeless powder? How would they re-invent black powder for that matter? I imagine they'd have to recover that knowledge from the ruins somehow. Might ask GM. The guns they have they can only use because of ancient stocks of ammunition scavenged from the ruins.