Hi DM:
I'm not advocating the use of 'wheel weights' directly, as in unaltered.
They were referenced as simply a 'material lead source'.
Now with that out of the way, I believe it's important to mention that you can take them and using the appropriate heated pots, melt out and seperate tha various components. This will give you a base of pure lead, to which you add back, the material components you want the blend to be, harder or softer or no blending at all.

As for the second method, it is often times far easier just to purchase the % of your lead directly, which is why, when lead is ordered from Corbin, they ship several different formats, meaning, bricks, coils in many diameters which is my preferance when working with the .172 and .223 cal.
I hope this helps with the understanding, again, this only represents MY POINT of view, as there are many ways to reach the desired results.

As this is a forum for 'reloading' I wanted to include this 'swaging method' as an alternative of knowledge to the standard bullet acquisition methods. It's also important to know, if one learns this may NOT be for them, you can ALWAYS just purchase the bullet from several sources, but, when you are interested in a bullet just the way YOU WANT IT, I can only tell you of my experience and say, I've NOT found any better methond for getting each reloading component just the way you want it as everything is CUSTOM with repeatable results time after time.
Thanks for the question - it helps others too!

bob