It is a tad bit more complicated than that but not really complicated at all. To answer your question......
According to Winchester's 1875 catalog,
“The effect of this change [from 44 Henry to the 44-40] is to increase the initial velocity of the arm from about 1,125 f.p.s. to 1,325 feet per second, reducing or flattening the trajectory and increasing the power and accuracy of the arm and giving it a penetration of about 4 inches, in pine board, at 1000 yards." Winchester described it to be effective and accurate to 500-600 yards."
According to Whelen (1941), Small Arms and Ballistics, the 44-40 Winchester "High Velocity" loads (1,565fps)[200gr softpoint/full jacketed penetrated 10/19 each respectively...7/8" thick soft pine boards from 15 feet.
The key here is bullet energy at impact, expanding or not. Depending on velocity at impact, the 44-40 200gr bullet can maintain greater than 400ft lbs of energy at 200 yards.
According to modern wimpy Winchester Super-X hunting ammo at only 1,190fps, energy maintained at impact is 900fps and 360ft lbs of energy at 200 yards.
https://winchester.com/Products/Ammu.../Super-X/X4440 The sole reason the 44-40 so misunderstood and underrated, as well as being considered a weak cartridge.
Ironically, the slower the bullet (around 800fts) the greater the penetration due to lack of soft point expansion, pending tissue/vs boards. Obviously the reason why the full metal jacket bullet penetrated further than the JSP.