I pounded a swaged bullet down a bit to get it swaged to about 0.360" and then pounded it through the bore of my Blackhawk. I found that the slug slips through the six chamber mouths of the cylinder with only very light resistance. It's my feeling that the chamber mouths match the groove diameter of the gun very closely based on this little experiment.

I'll load up that 11.0-grain 2400 load and try it, and if that doesn't work I'll cast some 358156 and try them with three or four powders. If I find nothing that shoots well, I might have someone take a look at my Blackhawk. If the 358156 shoots well, I'll either have the 358429 mold worked over or shop for an alternative sans gas checks.

I'll update this thread as I try to work this out.

Thanks to all!

Don't be the darkness.

America will perish while those who should be standing guard are satisfying their lusts.