RL28, you have probably heard the myth that lead alloys separate when melted. That is wrong! Once tin, and antimony are mixed it forms a true alloy, the elements form a true mixture. They cannot be separated once mixed.
Some will tell you all you have to do is melt the alloy, let it sit, the tin and antimony will "float" to the surface, you can then skim it off, leaving pure lead. The theory goes that the antimony and tin, being lighter separate and float out. No, since a mixture will stay mixed.
Your water pipe is most likely pure lead, with possibly ½ percent tin to make it flow better when the pipe was made. Flux it good to remove dirt and crud, you'll be fine.
As for your soft nosed bullets, that's been tried time and again. There was even a mold set that made the bullet in two parts, then the nose was GLUED to the harder base! Another method was to measure a certain weight of molten pure lead into a mold, then while still hot, pour the mold full of the harder base metal. It would seem to me to be a lot of trouble to get it right, also your production rate would be awful low.
I experimented with a hollow pointed Lyman mold for a 255 SWC .452 mold to be fired in my Ruger blackhawk 45 long colt. I cast them from the purest lead I could find. Lubed with 50-50 alox, I could push them close to 44 mag velocities, without leading, and reasonable accuracy. Then, shot into wet newsprint, they expanded similar to a hollow point jacketed bullet. I no longer have that Ruger, but still have the mold.
