Hollow Point Cavity Issues

[Michael J. Spangler]

alright guys i know i just saw a thread on this but i can't find it anywhere, i don't think the thread was labels as such i think it was about the mold or about a first try with a new mold or something

ok so here's my issue

Mold: mp .454-200 cramer HP

i noticed on my COWW cast boolits that the bottom of the HP cavity isn't always filled out well, and cash have some pretty ugly holes and inconsistencies in the bottom of it.

i looked back at my first boolits i cast that were a mix of 50/50 COWW and SOWW and they don't seem to have that issue at all so i don't think it's the alloy, i even added some pewter to the last 2 pots to sweeten it a bit encase that was the issue

should i be running hotter? is there a better way to pour? i use a lee bottom pour and try to pretty much center the stream in the hole, and pour away, but i've always done that from the beginning.
what am i missing? what should i try to solve it? i know the weight variance is pretty small, maybe 5 grains or so. i'm more worried about the balance being off because there's a bb sized hole off to once side of the bottom of the hollow point cavity.

is that an issue? I'm not shooting bullseye either so i'm not too worried but it would be nice to fix it and have pretty boolits right?

thanks in advance guys

[Dale53]

You must keep the pins hot to get good fill out. One way of doing that is to not let the mould sit empty for any period of time (even seconds count). When it is empty, it is cooling off. However, you MUST let the hollow nose of the bullet enough time to "set up" as you will bend the nose when dumping the bullet. It is a balancing act.

I find that running the metal at 725-750 degrees, casting fast, but having a manicurists fan to quickly cool the sprue and maintain mould temp (so it doesn't get too hot) works best for me. Like I said, a balancing act.

I run my hollow point moulds alloy at 20/1 lead/tin. I don't use many hollow point bullets so this doesn't represent much outlay (I have solid moulds for my practicing - they cast faster).

Try shooting your bullets from a rest - you MAY find it is much ado about nothing. I DO like near perfect bullets, tho' but I admit I may be more anal than need be...

Dale53

[runfiverun]

yeah it's cavitation around the pin tip.
get the pin hotter.

[Michael J. Spangler]

ok so i did some more casting on sunday and tried to keep an eye on the boolits to see how they were dropping.

i found that once the pot was depleted about halfway or so the stream from the bottom pour wasn't solid, more of a broken dribbling stream.

when start started to happen i noticed there was cavitation around the pins. so i guess i need to work with more of a full pot and add more sprues in a little more often to keep it running right for this mold.

figured i would give an update and see if this helps anyone out.

[Dale53]

Mike;
I use a couple of RCBS bottom pour pots. I keep the screw that adjusts the stream "strength" loose. As the level in the pot drops, I open the screw to maintain the flow at a steady rate. This is more or less a continuous process.

FWIW
Dale53

[geargnasher]

Listen to Dale, he has the good info and a good way to tell it.

Gear

[Michael J. Spangler]

good idea. i fiddled with the adjustment a touch as the pot ran low. now that i know the problem i'll keep an eye on it and see how that helps

thanks guys!