subsonic

I haven’t cast boolits, so I’m a complete noob here. I’m looking for something ~500g for subsonics, or the heaviest round that will stabilize in a 1/16 suppressed bolt gun. I can find .458 all day long, the heaviest I’ve seen .452 is one 300g pistol boolit. Where do you suggest I start? Thanks...

The I want a 9mm bolt gun thread got me thinking about this again, and I didn’t want to hijack it. I originally wanted a short threaded Marlin 45/70 to hunt with 400g+ suppressed sub Sonics. I’m worried about the slower twist not stabilizing a 400-500 cast slug. My next thought was to get a Howa...