1lb of tin to 10lbs of pure lead used to be a hard bullet! Elmer said so himself!
Read down in the lower right of the article located here:
BBHFarm Gallery :: Reloading Manuals :: aat

You have to get it into ingots. To do that, you CAN cut it first BUT get really coarse teeth saws and cut real slow. You can clean out the teeth because they will plug.

Your alloy can be mixed with wheel weights, 50/50 or so and for most applications, if they are sized right and not driven over 1100fps, you will have no problems. Mono or Linotype can be gotten from online sources as well as local junk yards. Lead free solder is just that, lead free but it is pure tin! (almost) It is a good source for tin that will make the bullets fill out better.

That will be the biggest problem, fill out. You will need some tin to get it to do so. There is another source of GREAT information on the web, here: From Ingot to Target: A Cast Bullet Guide For Handgunners, Table of Contents - Fryxell/Applegate

Check it out. If you can, get a Dutch oven for this job. It will hold bigger pieces.

Oh, if you saw it, make sure you save the shavings, they will melt too!