The challenge is to get technology to be lopsided in this way.
POD can be 1685 or later.
By the 1860s, we want some industry like textiles and steam engines, just like OTL. We also need chemistry to be advanced like OTL.
However, smoothbore muskets like the Brown Bess are the most commonly used frontline firearm and the artillery shells are also smoothbore (which means beyond visual range shots are impossible).
Now, in OTL, there were "rifled muskets" as early as Napoleon's time. No one really cared for them in OTL. The problem was that they were a pain to produce, easily to mess up reloading, and black powder smoke shot from a rifle would quickly place the shooter inside a cloud of smoke, negating the point of longer range.
Bonus points if you can get smokeless powder (which is actually 1870s OTL) in TTL, but still have muskets (possibly because no one put two and two together)