Sorry for the length of this post, but here goes...
Today I cast my first bullets. I cast a LOT. And almost all of them were bad. I made over 350 bullets, and I got 22 that were not totally awful.
Most were wrinkled and layered-looking, primarily at the nose, but some looked like I'd poured alloy in two different tries. I've seen the term "sharpei" bullets, and many of mine looked that wrinkled, but to varying degrees, especially the ones that looked like I'd poured twice.
I have a Lee 4-20 bottom pour casting pot connected to a PID controller, and I was running at 750F.
It was really obvious when my molds weren't hot - the alloy would start cooling on contact and only a little went into the mold. But after a while, I got good filling and nice, sharp bases. The bases were the only things that were nice though. I got a few instances of "sprue smearing" so I waited a little longer before cutting sprues and dumping the bullets. The only thing I didn't have happen was bullets deforming for being dropped too soon.
So I dug into Lyman's Cast Bullet Handbook 4th Edition and a couple other sources, and it looks like what I had going on was that the alloy and/or the molds were too cool.
Is there a rule of thumb for how hot the alloy (wheel weight in this case) should be for a given size and weight of bullet? I was using two Lee molds; their 452-200-RF flat point and their 452-228-1R RN mold; the flat point is a 6-cavity mold, and the RN is a two cavity mold. Is the amount of alloy in the pot
Second, I have read a lot about "cadence," but nowhere has anyone quantified cadence. How quickly should I pour into a 2-cavity or 6-cavity mold, how long should I give the sprue to harden, and how quickly should I work to cut the sprue and dump the bullets? Obviously it should be pretty quick, and the soft landing zone for those new bullets should be very close to where I'm pouring, but just how quickly is "pretty quick"? I'm sure it's no hard-and-fast time that fits every mold, but there's got to be some sort of starting point. Some numbers would be very helpful.
Lastly, I've read that it's useful to rest molds on the edge of the casting pot to keep them hot, and some people use a hot plate for this purpose. The idea seems to be related to using two molds in the same casting session, and/or keeping the mold(s) hot while adding alloy and bringing the pot back up to temperature - please correct me if I am not properly understanding. Well I had a very tough time getting either the 6- or 2- cavity mold to balance on the top of the pot at all because the handles seemed to be heavier than the molds and the mold blocks kept tipping off the pot. That makes me wonder how they'll sit on a hot plate... Do folks use a support for the handles?
Any guidance on this would be greatly appreciated.