When is a .46 long rimfire not a .46 long rimfire? Today!
My Ball & Williams Ballard sporting rifle arrived today. I immediately slugged the bore. To my surprise it was not .46 cal as the seller thought (it has no caliber markings). It is .435" groove diameter - a .44! No big deal, it doesn't matter to me. Chamber measurements are in my rough sketch. It dawned on me that my .44 S&W American heel bullets are perfect. They come from the mold at .435". I dropped a bullet into the chamber until it stopped on its own. Then measured back to the breach face - .940". The heel is .150 long. That gave a max case length of 1.090". Backing off .040" to allow for fouling, I came up with a case length of 1.050". As for a case, .44-40 is a better match than .44 mag. It is closer to the chamber base diameter. So I cut down a sized .44-40 case to 1.050", seated a .44S&WA bullet and it chambered perfectly.
It looks like I need to convert some cut down .44-40 brass to rimfire this week. :-)