Agreed, I shouldn't be facing 500 James cannons at Chancellorsville. I think there were maybe 60 in the entire rebel arsenal, they were variable in their form, and were discontinued after a few years. This is me playing as CSA so the Union had all those James guns...so it's doubly odd.
Napoleons should be more prevalent, those were the bread and butter. I mostly have parrots, amazingly I only have 1 full 10pdr ordnance battery by Gburg.
I've destroyed every single enemy artillery battery and bought every single cannon from the armory before every grand battle, 650 is the max you can achieve on hard mode by Gettysburg. 30% of my arsenal is 20pdrs.
Disclaimer: I only buy the 24pdrs with rep points. I generally spend rep on manpower.