Ballistic tables are like any chart...just a guide and not prefect. My doctor friend says there's NO absolutes in biology, I think the same can apply here.
BUT.......centerfire reloaders and shooters have for decades relied on ballistic tables in the back of reloading maunals...and while its not PERFECT, it does give you a place to start and something better than a SWAG. In my own use of them with a 30-06 the drop was almost spot on, allowing me to make some pretty long range shots.
Using the Lyman ballistic tables for the 58 cal 500 gr minie is also about spot on, for me, up to 200 yards. I regret I haven't shot further. This was at targets, not game.
Here's what Lyman published regarding 50 cal prb loads, 28" barrel and FFFg powder.
70grs, 1587fps & 1005 ft/lbs. at muzzle, 956fps and 365 ft/lbs @100yds
Sighted in at 50yds, drops 1.68" @75yds, -5.31" @100yds., -11.30" @125yds.
Energy; 1005 ft/lbs @muzzle, 575 ft/lbs @50yds, 312 ft/lbs @125yds
With a 370gr conical 90gr FFFg gave 1480 fps and 1797 ft/lbs @muzzle, 1038fps & 860ft/lbs @100yds.
sighted in at 50yds, drops 1.4" @75yds, -4.3" @100 yds, -9.2" @125yds.
So the trajectory of the 2 bullets are close, but the conical has lots more retained velocity and energy at the same ranges for a 20 grain increase in powder.
Btw, a 90 gr load of FFFG w/ a prb gives 431 ft/lbs @100 yards...I figured I'd be crucified if I didn't include that piece of info.
Remember their data used FFFg for the 50 cal, and you are using FFg, this WILL make a difference.
I'm gonna kick the hornets nest...their data, while dated, is still relevant imho. And they did lots of testing using FFg vs FFFg and their test showed you could use 40% less FFFg and get the same velocity as 40% more charge of FFg. At least in the 54 caliber you could. Here's some of their findings.
Example
54 cal prb
100 grs FFFg =1740fps
100grs FFg= 1538fps
140grs FFg= 1779fps.
You can find the book used for cheap, try abebooks, they seem to have it most times I've looked.