I will mostly avoid best hunting bullets since there are many fine choices for sabot use.

Target shooting though with powder charges close to your hunting loads, ive found a few that i really like.

The Harvester PT Golds are fairly cheap if bought in lots of 150+ otherwise the shipping makes them a bit expensive. The plus side is they seem to be pretty good for hunting too. Accuracy has been excellent over a very large velocity range.

The good old 250gr XTP has been used in numerous reviews about accuracy. Even Savage uses them for test firing their guns at much higher speeds. Price isnt too bad but the GoldDot 250gr has given me as good or better accuracy. I also think the GoldDot are a better hunting option for most MLs vs the XTP.

A bullet that has caught my eye just for target/fun shooting is the 45-225gr FTX. Under $30/100, a little less recoil and really fun to vaporize water jugs. I wouldn't use them for hunting deer but they would just destroy varmints.

If you bore is tight like many T/Cs, the Harvester Black Crushrib with a .452 bullet should be about right. Some 45s though are .451 and with those a Harvester Smooth Short(sub 300gr) or MMP HPH-24 may fit better. Ive found the thinner MMP 3P-EZ loads nice but can be a bit more "bullet finicky". Several Barnes, Harvesters and Noslers run closer to .451. Speer also offers one .451 300gr. Im not sure if a thousandth will make a big difference but i thought the info might be useful since the Barnes you are using for hunting is likely .451 or even .450.

My tightest 50 bore (.500) though really likes the .452 225gr FTX and a Harvester short black even though it loads a tad easy IMO.