I took some shots at a few coots at the farther end of my range (25 yards) with my .50 smoothbore. 45 gr. powder, 1 oz #6 Bismuth shot.
I think that where your gun patterns/how the gun fits and where it points are certainly of #1 importance. Having said that, I think that an ounce of shot and 45 grains of powder is pretty far from a “square load”/equal volume powder and shot.
I have never tried something as small as a .50 loaded with shot and such a small charge of black at game shooting. Seems like that would make for a pretty long shot column. However, if that patterns well and to point of aim, it might just do the job?.
Turner Kirkland said that if his load would penetrate through one side of a soup can at the range he was shooting, he deemed it good enough.
I hunted doves over decoys and at the range we were shooting at, my 14 gauge loaded with an ounce of #7s (#7 I bought at Sportsman’s Warehouse) was working well. I used just one hard .135” nitro card over the powder, no cushion, the lead shot and 2-thin over shot cards on top. It was bringing them down real well.
If I was you, I’d go for a larger bore size and make certain that it hits where you point it. Wounding game is something we do not want to do. It is our responsibility to use something big enough to kill what we hit without causing a lot of suffering on the part of the game being shot. I believe that #7 is about perfect for those tough ring necked Eurasian doves as I seemed to be just dusting them with #7-1/2s so I settled on #7. So, you have to do a little patterning and testing for penetration before you can say it’s a good gun and load.
Nothing wrong with having an extra gun for shotgun work but if you want to have just one gun for both shot and ball work, try using a little larger gun.