Never had a 54 but do have 50. What, if any, advantage is there shooting a projectile that is 0.04 larger? Just curious
OMG, WHERE do I start?
Well just talkin' round ball..., you have more weight and more diameter in the .530 vs. .490 round ball..., 225 grains vs 175 grains......does that "count"; heck if I can tell....
Too Many Variables...
First if the load you use in your fifty will punch a hole through the deer, and my fifty-four does the same....does it matter to the deer how "dead" they are ? ( Not really.)
So "on paper" my heavier ball will have more inertia on impact at 100 yards than will your ball, BUT...., we have to be at 100 yards or perhaps a tiny bit farther for that to matter much if at all....
Beyond round ball...,
IF you bought a 1:48 twist rate .50 caliber rifle, and I have a 1:66 round bottom rifled barrel on my .54..., you can use a conical bullet weighing 250 grains, and thus negate my weight advantage since I'm limited to round ball. Plus that bullet flies a bit better than my round ball and doesn't shed velocity as fast....
So the only advantage I have would be .030 larger diameter bullet. The deer, or the elk (with that weight you can now go for elk) won't know the difference....unless AGAIN we are at maximum range. (Which isn't usually a good idea.)
This ^^^ is of course assuming equal muzzle velocities....,
So if you're using 90 grains of powder for your .490 ball and I'm using 75 grains for my .530..., you may actually penetrate better than mine...at 100 yards...but again we have to pushing the loads to the limit.
With that faster load you get a flatter trajectory for the round ball than I get with mine..., that might be a plus for you with your .490 ball. Same thing for conicals.
THEN we get into alloys. A 1/2" hole is just that..., now do you need the ball to deform OR do you need it to penetrate and come out the other side of your game animal and deformation is a bonus? So what happens if you use a little tin in your casting lead, and a different patch so it loads and shoots well? At long range my soft lead .530 ball might just deform so much it stops inside the animal as it mushrooms, while your harder .490 ball might zip right through, immediately collapsing both lungs. Result, I have some tracking to do while you walk over and collect your deer. Does that matter to you? Does that matter to me?
(OH and don't fall for the "energy transfer" stuff when it comes to black powder..., not going fast enough...., so all you can depend on is the actual hole the bullet makes, and most often with a broadside shot, two holes in the animal drop it quicker than one)
How about over-the-counter stuff? How about hunting buddies?
So you get to your hunting area and realize you left your bullets at home...
Do your buddies shoot .50 or do they all shoot .54s and you're out of luck as they can share bullets but you can't. The reverse applies for me with my .54 if all my friends shoot .50s.
It's 8:30 pm and you realize that you left the bullet bag at the range when you sighted in last Saturday, and you have to go out to Wally World to get bullets. Do they carry .490? Do they carry .530? Maybe they only carry .490 ball so your .50 has that advantage. Does everybody in the area shoot a .490 so they are out but they have a box of .530 ball, so I would be "in luck" but you wouldn't? Do you have a mold so this question is moot??
So as I wrote, LOTS of variables.
Whatever you use, get very good with it..., and it probably won't matter between a .50 and a .54
LD