Have you tried just holding the mold an inch or two under the spout, and move the sprue plate hole under the silver stream?  My bottom pour pot didn't come with any sort of bracket to rest the mold on, so I just hold it under the pot and move each cavity so that it's under the stream.

I've never even heard of holding the sprue plate directly against the spout. I've always used xsquidgator's technique with my old SAECO pot.

Without a decent sprue on top, how do you keep a void from forming in the bullet as the lead cools and shrinks?

Okay.  This is one of those "it's the way I was taught and I thought everyone did it this way" moments.

I made definitely hundreds, and possibly thousands, of bullets in varying calibers with this pot and my dad's Lyman molds back in the 70s.  All exactly the same way, all without voids.

Put the mold in place, lift the handle for a second or so, release to close the spigot.  Wait a second, then remove with a slight twist of the wrist.  The sprue plate will have a very small cone of lead at the bottom of the hole.  Whack the sprue plate sideways with a piece of wood to shear off that cone, and open the mold to drop the bullet.  The first few are always rejects till the mold is up to temp, then easy peasy.  No muss, no fuss, and especially, no mess.  The thing is, once I lift the handle to let the lead flow, I can leave it open for as long as I want.  Once the mold is full, it's full, and no more lead will flow.  The sprue plate held up against the spigot seals the flow.  All I have to do is close the spigot, wait a second or so, then remove.  Obviously, since a second or so is sufficient, that's all the time I leave it open.  The point is that it doesn't matter, because there is a mold to pot seal that doesn't seem to exist with the Lee mold.

Now, my guess is that the spigot at the bottom of the pot is not quite as deep as the Lyman sprue plates are thick, thereby allowing the two to mate but still leave room below the spigot to form the sprue.  At least with my Lyman molds.  I'll have to measure the thickness of the Lee mold's plate.  Also, and I'm guessing here, the angles on the holes on the Lee mold may not be a tight fit like those on the Lyman molds have.

As fast as the lead flows from the pot, how do you keep from pouring lead all over?  I guess I can try this "new" technique.  Just seems wasteful of lead and much more apt to cause burns compared with the way I'm used to doing it.

Perhaps "wasteful" was the wrong word to use.  But the level in the pot sure went down a lot faster.  And the cleanup was a lot more than I was used to, since the lead was spraying several inches each time, only varying by direction.  I had to scrape it off the bench, the bottom of the pot frame, the floor, etc., and I need to replace some plastic sheeting that got splashed.  I'm simply not used to any of that.

One other oddity I noticed is that this mold is dropping .405" boolits.  I thought they would be closer to .401".

I'm not worried about the .405" diameter.  At least not yet.  I'm going to run them through the sizing die this evening.  I just thought they would be closer is all.

Hmm, it never really occurred to me to try it your way.

Like I mentioned above, it was how I was taught with the molds my dad had, and it worked on all of them.  I didn't know there was any other way.

I developed my technique on my own through a lot of trial and error.  I have a fairly good amount of pour that solidifies in one long run connecting all 6 mold cavities.  As Jesse points out, no waste since those just go back into the pot.

Yeah, they go back in the pot, but the pot drains down faster.  This also explains the comment about throwing the rejects and sprue plate cutoffs back into the pot to cool the lead back down in the "how to" thread about bullet casting. I never really understood how that has much effect, since once I'm not making rejects my sprue cutoffs are only about 1/4" round x 1/16" thick.  Takes a lot of those to have any effect.

I found that I have to make my bullets this way in order to get a nice flat bullet base without any voids.  Pour into the cavity until it overflows a little, then pour for another little bit to keep some pressure into the sprue hole (or else a void will form), then while keeping the pour handle up just move the mold an inch or so down to the next cavity and keep doing that until all six have been poured.  In my experience, each raise and lower of the pour handle is a chance for something to get stuck under the valve seat and cause a drip.  As it is, i have to rotate the valve stem some every now and then to get the pour valve to shut off properly with no drips.

I was lucky that someone showed me how to use reloading equipment when I was getting started, but i didn't know anyone casting when i started that and had to just kind of trial-and-error it out.

Oh, on the .405" diameter, they sized down just fine last night.

Question though.  I cast these on Saturday, and water quenched them.  Sized them last night.  Is that close enough time wise to not screw them up?  If so, how long should I wait before I shoot them?  And will they still harden up if I load them but just wait to shoot, or should I wait and then load them into shells?