The babbitt I can get is Nickel Babbitt, that we use at the sawmill for sawguides. Our supplier is located about 18 miles away from me, and all I have to do is ask. I'll combine some of the babbitt with pure lead to make my bullets. The more babbitt, the harder they get.
I cast a few bullets at work one day of the pure babbitt, and took them home to weigh them. The mold was supposed to be casting some .454 bullets @ 252 gr. The actual weight was 185 grains each, as weighed on my Pact BBK-II scale. That's a heck of a difference.
My cast .309 bullets average 159 grains, as opposed the the advertised weight of 160. My .475 bullets are averaging 405 grains after being sized and lubed.
I can't recall offhand what the actual weights if the .430 and .452 bullets are, but they have gone through 8 inches of pressure treated pine without serious deformation.