Has anybody ever used the T/C round ball moulds?
I have a new 50 Caliber/.490" that I bought about 25 years ago,but I've never tried it.Since I've retired,I shoot more than I used to,but I can afford store-boughts now.
The set I have are "malleable iron" and look like they might be made by Lyman.
They'll fit my old Lyman small mould handles from the 50's but they wont close when I put them on a new set of large mould handles that are from the 80's.
Looking at the catalogs,it looks like Lyman has changed their mould handles again. I wonder which size handle will fit these T/C blocks now.

If they fit the small Lyman handles, you're in business, no need to use the large handles...only adds more weight to hold up.

As for casting RB's, there is no real trick to it except getting the melt temperature right as well as mold temp. Cast a small batch & weigh your balls when they cool, if they are falling in the 176-182 grain range, you're good to go. If you get wide variations in weight from one to another, you've got troubles. May be nothing more than too cool a melt or mold...or maybe air voids. The purer the lead, the more fussy it's going to be when casting but with a little fine tuning, you should be good to go.