I have been casting sense 1971 and only for a couple of sessions did I save sprews for my next sessions. I then figured out that it only takes a couple of seconds to pick them up and put them back in the pot with no effect on the temp of the melt, and also that gave my mold enough time cool for the next sprew cutting. My method is to fill the mold wait a few seconds cut the sprew dump the boolits fill the mold pick up the sprews put them in the pot and then cut the sprews again and continue the process. This is done with gloves on of course, the trick is to keep the melt from splashing. What I do is as I put the sprews back in the melt the glove hand with sprews opens over the melt to prevent any splash from coming out of the pot. By doing this I get the full use of all the lead I've melted in that pot of lead.