If the ball is cast from pure lead, its soft enough to be reformed in a Steel mold- I am not so sure about using an Aluminum alloy mold for this purpose-- to reduce the size of the sprue.
More importantly, testing was done just a year ago, that says that the location of the sprue is NOT important for accuracy, as we all believed, and had been taught. The Weight of the balls being consistent has much more to do with their accuracy. :hmm: :thumbsup:
If you are loading ( casting, and shaping balls) for a replica Ferguson, Take the time to cut or file the sprue off as close to the diameter as possible, and then weigh the balls. Balls that are lighter in weight in all Probability have casting " bubbles" in the lead, under the sprue, and should be set aside for plinking loads, or to put back in the pot to be recast.
The bubbles show up in the cast balls due, primarily to the lead being too cool by the time the last lead is entering the mold.
Coolness can be the result of:
1. melt temperature in the pot;
2. holding the mold too far from a bottom pour spout;
3. using a ladle that is Not kept hot between pours;
4. holding the spout of a ladle too far from the mold when the lead is poured;
5. waiting too long to pour the lead into the mold; and
6. pouring lead into a mold that has too small a hole in the sprue plate( cut-off plate), which allows the lead to cool before the mold is filled.
These technical issues become an even more critical problem when using gang( multi-cavity) molds.
If you are going to use a steel mold set of blocks as a swaging tool in your vise, take care in how you use the vise to press the two halves together. Pad the jaws, so that its teeth don't damage the mold blocks. Don't expect it to squeeze out a lot of excess lead- MOLDS are simply not designed for that purpose.
A better way to use a mold to reduce the size of sprues, is to put the ball back into the mold blocks with the sprue protruding up through the hole in the blocks, with the sprue cutter plate left OPEN. Then use a file, chisel, or knife carefully to file or cut off the lead sticking up through the hole.
Tanner makes old fashion scissor style molds of brass, that have no cut-off plates attached. He sells a set of wire "nippers" that have a curved set of blades to cut off the sprues even with the curve of the ball. There are " side cutters" for cutting rod, and wire available that can also be used with soft lead to cut off the sprues cleanly.
Paul