I haven’t tried them in a 458, but for a small game load instead of Ganyana’s round ball load a lightweight SWC in 458 might be another option. I have a CBE mould designated 458260. I think it was originally designed for an obscure English BP Express cartridge. I bought it years ago to make plinking loads for a 45/70. It’s a PB SWC style design that would likely be more accurate and easier to load than a round ball.
CBE no longer list that mould but I’m sure something similar could be had from Accurate in the US. Something like an upsized version of Keith’s 452424 with a diameter of 0.462/3 out the mould would be the ticket.
