Poncaguy;
I have a Handi in .44mag., or did .
Last week I reamed it to .445 SM.
Really nice shooter, even a 310gr FN at 1650fps is very comfortable.
AA 1680/ WC 680 is the powder AA lists, actually the only powder they list for the .445 SM.
I have just reamed 2 molds so as to have .434" bullets for my .431" barrel.
I made the reamer for the molds, just make a profile of the driving bands, cut flutes with a mototool and diamond cutoff disc, turned the reamer with pliers while closing the handles and had .435" molds with no detectable, at least by me, runout.
Yesterday, I shot some .432" bullets and had decent groups.
I cannot post pictures here, only forum I cannot, so just have to say, the groups were pretty good. :-)