Casting 400+ Grain Bullets

[ballisti-cast]

I made a customer a .480 405 grain 3 cavity mold in a 4 cavity block. I did some testing with it and found I had to wait 15-20 seconds between casts to keep the mold cool enough so it didn't cast frosty bullets. Had the wheel weight lead at around 775 F. I haven't cast many bullets above 250 grains and haven't ran into this issue with the lighter bullets. Is the 15-20 second wait time between casts to be expected or something I'm doing wrong? Also would brass or aluminum blocks make a difference? We currently make all of our molds in iron. I did a bit of searching through the forums and couldn't find anything on the subject. Any input is greatly appreciated. Thanks.

[Larry Gibson]

That is about the standard wait time for either my iron or aluminum 400 - 500 gr moulds. Your doing nothing wrong, just a lot more heat (not in degrees but in volume of heat due to mass of alloy) to dissapate and cool off than with a smaller bullet. Figure about 3 times as much heat than with a 150 gr bullet or 2 times as much as with a 200 gr bullet.

Larry Gibson

[runfiverun]

cut the heat down on the pot to about 675.
the larger boolits seem to pour better with a ladle,or with direct pouring from a bottom spout right into the sprue hole.
it's easy to get a mold hot with that much lead in them, keeping them cool is the trick.

[Jailer]

Keep your sprue puddle small. With a large bullet like that you don't need the extra heat of a large sprue puddle heat soaking your sprue plate.

And like R5R said, cut the heat back a bit on your pot.

[Catshooter]

And there's nothing wrong with a frosty boolit, either.


Cat

[rintinglen]

I have a 4 cavity 457-192 Lyman that gives me the same issues. In three casts , it is hot, and I am standing there waiting. I get about 2 1/3 casts a minute, and the boolits are frosty. I tried Bruce B's speed casting tip of a wet wrag, and found it helped produce more boolits but did not help with the frosting issue.

[southpaw]

I have found that casting with 2 moulds helps me with the wait. I get one up to temp then start working the second one in. Might as well use the time between cast to make more boolits.

I too would also lower the temp to 700* or a little under unless things started to go south by doing so.

Jerry Jr.

[warf73]

Like a few others have said lower your heat. I cast between 700~725 and get 3 casts per min. with a 2 cavity brass mold.
I would go lower in temp but my pot freezes up once i get under 700* (according to my Lyman thermo). Brass is different than alum but I do get to the point were I'm starting to wait on the spur to get solid. Once I get to that point I cool the spur down with a damp towl and that helps for 6 or so pours then I must do it again.

[Lloyd Smale]

What i will do with molds like that is cast them as a 2 cav. rotating what two cavitys i use. I find it faster then waiting for molds to cool off and with those big bullets sometimes with certain alloys you will actually get voids where the bullet is frosted. Especailly in the thin areas between the cavitys in the mold.

[L Ross]

Am I the only caster using a fan? I cast a lot of bullets in binary alloys of 1/20 thru 1/40, I find high temps a must. I use a fan to cool the moulds and solidify the sprues. I always find a large sprue a must for consistency.

Duke

[Larry Gibson]

I also cast most often at 700 - 725, occasionally 750 with small bullet 6 cavity moulds. I also will use 2 or 3 moulds at one time which keeps the mould temp right and casts a lot of various bullets quick. And I also use a small fan when casting in hot weather blowing over the moulds.

Larry Gibson