I'm with Fiver on the nice weld bead.... next part I have reservations about even discussing so will preface saying you didn't hear it from me.... think in the abstract,to whack or not whack(sprue plate abuse?); Recent changes in the ole casting setup,got RUNNOFT out of the best durn setup,ever. Saw a change from a std propane torch head,which was there to coax a little more performance out of recalcitrant moulds....to a Coleman single burner,available at Walmert,camp burner. Here's the possible abuse. Once your mould is up to temp but the bullet's base "needs" some experimental help,flip it sprue plate down over the single burner.Huge difference in the heat transfer between the small semi focused heat of the torch head and the way the single burner's act. Like a tig torch vs OA torch,both using the same rod. Watch what happens to not only the base,but you should see,by continued abuse.....it starts to "run" up into the bullets body.
Sorry for the run on paragraph,haven't had any coffee yet.... pots over there gurgling.
Since this is the lube section and coffee is a lube of sorts..... more abstractions. Terrible pic to be sure,it's my favorite handmade cup and cream pitcher. Think about these shapes or profiles. When heat is sucked out of the sprue.....the profile changes as it runs into the bullet body. I had one pic that takes it even further because the auto flash kicked in. It "threw" a shadow of my cup on the wall in the background. This is applicable as well,it's back to the alloys ability to utilize the heat.
I found some time back that if it flipped the warming moulds over on the hotplate sprue plate down that I had better "first pour" results . The 8C H&G and the brass MP hollow base have been very adamant about it in fact . I think it was the MP 462-425 HB/PB that actually got me doing it vs just pouring extra back in the pot over the sprue plate .
I pretty much just give them all the last couple of minutes in warm up the flip face down now as part of my habit building . Of course some take more than others ........"heat soak" might be the words we're looking for in this case .
"Apparently" aluminum is a heat sink RB. To the effect that raising sprue plate temps to the "extreme".... which,is abuse on anything more valuable than a 23$ Lee ghetto master....
This extra heat is QUICKLY sucked down into the bullet body. I swear,had several bullets actually crack in half coming off the cavity/block the other day. Which is what I was "trying" to convey with the coffee cup pic. This heat reaction? overwhelms the whole shebang.... but that was on the extreme. Get it right,with an alloy that can handle it and I'll go to the 2$ bet window you can't drive these things fast enough....twists and rpm's be damn'd. Just sayin.
A little copper goes a long way .
I have trouble with bases but they are consistently and uniformly messed up so I can roll with it .
I've had the opportunity to shoot enough rifles with different twists to be able to say it matters and has a significant impact on speeds available per alloy .
I guess I hobble myself by using only alloys I would hunt with . On they other hand I guess that leaves me ahead of the game when it comes to wanting to hunt with a real performance gun and load only to discover that it doesn't shoot the same way with a different alloy ......
Only that brass tank and the H&G 8× spend a long time face down . Maybe it's my technique . Hot pot , work flow , flakey alloys ...