Why bother? If you want shotshells, CCI makes a pretty decent one for the .45 Colt and that IS appropriate for the .460. I've shot those rounds and they'd rip a snake up beyond striking distances (at least any snake in N. America) and are fun to shoot. Don
I know it is an old post but the information was leading me in the direction of moon clips as some said I could shoot .45acp and .45LC as well. I am glad I checked with the factory....here's is a quote from S&W:
"This gun is only meant to shoot .460 S&W Magnum, .454 Casull and .45Colt. Some of our guns come with cylinders cut for moon clips but not the 460 revolvers. Unfortunately we do not offer cutting cylinders for moon clips as a service right now. If you find someone who will cut the cylinder for moon clips, then the head space will be changed and you will no longer be able to shoot anything other than .45 ACP. Misfires will likely be the result. This will void your warranty."