New caster with questions on sprues and bullet out of round

[Buckshot Bowman]

Hello Lads,
I am very new to casting, as I am a black powder shooter and need big bullets. I have overcome a lot of the beginner problems, and am getting nice shiny bullet that are fully filled, and the weights are coming out right.
My questions, are most of my sprues on the bullets are a tad higher than the base, I also find different measurement around the base, some spots are .459 and others as low as .457.

I am using a RCBS bottom pour, I have a thermometer that reads 750 on a 1-20 tin lead mix I flux with marvelflux, my moulds are heated on a hot plate and are plenty hot and clean. I wait till the sprue frosts and count to four before cutting sprues.

How tight should the sprue plate be on mould, and how tight do you hold your handles, I have gone from a good hold to a death grip, These things aren't covered in the manuals and I am getting tired of throwing bullets back into the pot.

Thanks

[runfiverun]

well part of the problem is... tolerance stacking in modern production.
your mold might just be a little bit out of round, or you may be getting slightly different mold temps from not maintaining an even count from pour to pour.
you could lap the mold to make it more round.

your sprue sticking up is nothing more than temp when you cut it, or if you are hitting the plate it could be bouncing a bit.
try opening the cutter sooner.

I just barely hold the handles enough to keep the mold closed, this prevents fatigue and maintains an even constant pressure on the mold.
if you want perfect even ness they do sell mold locks, these hold the mold closed for you.

[44man]

When a mold heats the cavity gets smaller towards each block but gets larger at the parting line. metal expansion!
Make sure the sprue taper is sharp and tap it to cut with a slight downward motion. The plate tightness will differ mold to mold, some do best when loose, etc. If it is riding up, tighten a little.

[Walter Laich]

As far as sprue plate tightness mine will fall open when I hold it vertically. It isn't latched when I do this. Any tighter and I have problems with base filling out.

[reloader28]

I dont see a problem, since your new to this.
Load em up and shoot em.
I think you'll find they work perfectly fine. Out of round dont matter if they're big enough, and if its soft enogh it dont matter anyway. Cut the sprue with a knife if you want.
Later on, with more practice it will come to you.

Basically, nobody showed me how to cast. I learned as I went and shot a LOT of ugly, wrinkled, bad fill out, out of round junk boolits. Guess what? They all shot fine.
Then I found this site and really started learning, but I think most people over think this. Just load em up and have fun. You'll get it figured out after a while.

Just my 2 cents