Sensop. Wheel weight metal makes for some good bullets. You can use it as is, alloy it with linotype (if you can find some) heat treat it to make it harder. Good stuff, and usually reasonably priced. I've even had gas stations give it to me, but I think those days are gone forever.
You apparently already have the Lyman cast lead book, so here are a few other sources of information. The NRA has a book,CAST BULLETS by Col. E. Harrison, Ret. There is also a supplement #1 to the book. There are two good articles in the suplement on using heat treated bullets on African big game. If you can find a copy of the RCBS cast lead handbook, it has some good stuff, and the simplest directions for heat treating bullets I've seem. Wolfe Publishing put out a few paperback books on cast lead bullets as well. I think their web address is (www.handloadermagazine.com).
I have the RCBS mold, #37-250, a gas check mold, that I plan on using in a couple of .375 caliber rifles I use. It looks like a real winner for the 38-55.
I hope this helps. You can E-mail me with any questions, if you want.