I packed my 4" M29 back in the 90's up in the bush when I was a Forestry Officer. Never had to use it. 280gr. SWC's at 1,210fps was my load - iirc, 17.0gr. (or maybe 15gr.) AL7.

Shot placement is needed, with sufficient penetration.

A 280gr. SWC is better than a 240gr. SWC, but a 300gr. SWC is better than both, all hard cast, of course & loaded to the nuts.

Spine or brain are best targets, I would imagine.

A good 1 to 1 1/2 ounce 12 bore slug is better yet, I would expect.

Brenneke or Gualandi come to mind.

They shot quite accurately in my rifled Mossberg at 30 yards. About a 2" hole for 5 shots, elbow rest on the bench.
496gr. @ 1,610fps - factory Challenger(CDN)ammo.

https://www.youtube.com/watch?v=TCxA2IYneqM