Well the hope is that they are wheel weight alloy but with scuba weights their really ain't no telling.
Just be careful when smelting them down just in case they have any trapped water in them. Let them heat up nice and slow to avoid the tinsel fairy.
You might try checking to see about what temp they become liquidus at. This is the stage where it just gets watery, and isn't clumpy or have any solid chunks still in it. You might look through this,
Cast Bullet Alloys and see about where you should be, but with most WW alloy I have messed with, it usually is around this stage in the 565 - 595 degree range or right at 600'ish for sure.
That said it might hit just a touch higher or lower depending on just what it actually is. As long as your not seeing the clumpy oatmeal looking stuff in it you should be good. Even so I would only try pouring up a small amount first with a ladle and see how the bullets come out, especially if your using a bottom pour. If it has any zinc in it you probably don't want to introduce that into your pouring pot.
