any idea what causes this cracking ?

[varmint243]

any idea what causes this cracking ?
about half of the boolits I cast from this mould are cracked.
believe it or not they shoot fine after a trip thru the lube-sizer pushes the cracked piece back into place

82327

[MarkP]

Taking out of mold while too hot can cause this, a slight hang up and a tap will cause drive bands to break. Sometimes the heal of plain base will do this usually happens when my mold is getting too hot.

[btroj]

Mark is right, mould too hot. Bullet dropped too soon.

Slow your tempo a bit or use a small fan to cool the mould after each pour but before cutting sprue. This will keep mould temp in the right range and stop this issue. It will also give more consistent bullet sizes and weights.

[runfiverun]

it can also be a burr in the mold catching the soft boolit and pulling on it when it comes from the mold.

[Dusty Bannister]

Are you dropping them too hot, from a height or just opening the mold so the castings can only fall a few inches or less, onto layers of soft folded towel or other non-melting fabric. Almost looks like the photo shows it hitting on the edge on a hard surface. Dusty

[theperfessor]

+1 to what r5r said, check for a burr and wait for a couple of seconds after you cut the sprue before you open the mold.

[MT Gianni]

Go over the mold with a #2 lead pencil. Hit all areas with the graphite end, then break the point and burnish it off with the wood. That should let you feel if there are any burrs and take care of most of them.

[varmint243]

Thank You to everyone for you input.

I think it is probably a little bit of all the things mentioned.
The mould has some very light pitting from some surface rust and I have to whack the pivot pin pretty hard sometimes.
I am a pistol shooter so I need a lot of bullets, relative casting speed is important, and bullet accuracy is also relative, so I open the mould as soon as the sprue flashes over.
I drop them about 6" onto the pile of bullets that I am casting.

I think I will put the mould in the lathe and polish it with a dremel and a cratex wheel a little.
I will let the mould cool for a few seconds longer
I will try to create a better arrangement for when the bullets drop from the mould


thanks, DaveV

[bruce381]

I use a old cotton towel folded over and as my pile build up I move the boolits so i always drop on towel only.

[lwknight]

I cast mostly for speed. I learned that it is necessary to let the mold contact the table with a folded towel on it to catch the smoking hot little buggers gently.

[44man]

A sure sign of lead still not set up yet. Speed is always a loss in the end. You might make 20 more boolits then someone else in the same time frame but have more rejects.

[Shiloh]

it can also be a burr in the mold catching the soft boolit and pulling on it when it comes from the mold.

Have LEE six banger 9mm mold that had the second cavity get damage. The burr caused a tear on the base. I ground it off with a round burr in a flex shaft. There is a tiny divot in the boolit, but it no longer hangs up. I separated about 30 boolits once. Loaded and fired them as a test. No difference.
The gun and targets can't tell.

Shiloh

[Iron Mike Golf]

I have a 452460 that'll do that on a cavity. I open it by tapping the handle hinge bolt and let let the vibration separate the mold blocks. Less than 1% have a damaged drive band when I do that.