What causes....?

[philthephlier]

perfectly filled out cavities to drop bullets with "craters" where the sprues are cut off?

[peerlesscowboy]

cut the sprue too soon?

[cbrick]

Yep, simply wait a few more seconds for the sprue to freeze before cutting.

Rick

[ColColt]

Yep, it's happened to me while rushing through to get things going. Spruce...er, sprue has to be hard.

[Ohio Rusty]

I have also found that if I have WW lead too hot, the lead wants to crystalize and literally break off instead of cut at the sprue. Those break off's leave a crater also. I can tell when that is happening as the boolits also become frosty.
Ohio Rusty ><>

[cbrick]

Yep, it's happened to me while rushing through to get things going. Spruce...er, sprue has to be hard.

Never could figure out how you get a wooden sprue plate to work for you. How often do they need to be changed? :mrgreen:

Rick

[1Shirt]

One of the old timers discribed that particular look on the base as looking like a goats hoo-hoo! Kind if thing it is hard to remember don't ya know. Does make a difference in blt weights however, and the smaller the cal, the more the issue of weight consistanciy plays in. No big deal on 44 plain base revolver blts, big deal on 22's for horner etc.
1Shirt!:coffeecom

[lwknight]

Puddle the spru plate bigger. It will heat up the plate more so that the alloy solidifies in the cavity before the plate. When the plate is too cool , the hardened alloy will not flow into the cavity ti fill the voids caused by shrinkage.

[geargnasher]

To me, the little goat's "hoo-hoo" crater (an apt description) means perfect. It means the sprue was cut soon enough to be done by hand, and that if the boolit dropped from the blocks right away into the bucket of quench water, it was the perfect temperature. Another tip I picked up here. If you get good and consistent at it, you will get maximum hardness from the quench without the need for further heat treating.

What makes it happen is alloy shrinkage after the sprue is cut. The sprue plate would have to be really loose to "tear out a chunk" like some think is happening. The sprue plate shears it clean, but the boolit continues to suck-in just a bit, an effect similar to the dross-induced "coring" that happens when some alloys cool. The shape is caused by the larger dentrite trees of the metal on the primary phase of solidification.

Gear