Why doesn't the base fill out?

[mugsie]

I'm casting the Keith bullet in 45LC Lyman 452424 which casts a 255g boolet. My problem lately has been the bullets look nice, but the base of the bullet doesn't fill out completely. Where I should have a nice sharp driving band, it sorta rounds at the top near the spru plate. They seem to shoot OK but I still had to throw a lot back in the pot. I am leaving a very generous puddle on top so there's something to pull down into the mold, and I'm pouring from a Lyman ladle. An ideas why this is happening? I don't see it on my other bullets that I cast. I use wheel weights with 2% or so tim added.

Thanks for the help....

[joeb33050]

Yesterday I had the same problem, occasionally, with Lyman 457193 405 grain. It happened when things weren't HOT enough. Keeping that puddle bigger and in place longer, lladle in contact longer, fixed the problem for me. Also has worked with other molds over the years. It takes me a while to learn how to cast with some new molds. This is the second time casting with this mold, another 1-3 sessions and I'll have it figured out.
joe b.

[T-Bird]

I've had the same problem with that mould and 429421 my conclusion also was too little heat.It sometimes helps to leave the ladle mouth in contact with the mould mouth a little longer before you separate them until things heat up. I also think that being sure you have a full ladle helps be sure that you have enough "head pressure" to fill it out especially before it is really hot enough. Shoot straight, T-Bird

[44man]

It is great to read that many others cast the same way I do. Keep contact with the ladle until the boolit gets all the lead it needs, never depend on the sprue alone. And more heat if problems occur.

[montana_charlie]

Make sure air can vent from the sprue plate/mould top junction.
Break the edges of the blocks, or loosen the sprue plate pivot screw.

A loosened pivot doesn't help very much...if you keep the pouring spout hard against the sprue plate for too long.
CM

[American]

Make sure air can vent from the sprue plate/mould top junction.
Break the edges of the blocks, or loosen the sprue plate pivot screw.

A loosened pivot doesn't help very much...if you keep the pouring spout hard against the sprue plate for too long.
CM

Read where someone said to use a stone to *slightly* knock the edges off the top inner (mating surfaces) of the mold blocks so as to create a small vent under the plate.

Good idea or bad?

I'm having the same issues, although many do turn out fine and keeping it hotter does seem to help. And I'm using WW and have added no tin yet, which I hear helps with fillout - is this considered a "fillout" issue? I'm adding the tin next time.

[S.R.Custom]

I use this very same mould sometimes...

Dunno what your cooling routine is when the mould starts to get too hot, but be mindful of the fact that the sprue plate can get too cold. Except to dump a bullet, I keep the mould blocks clamped together and the sprue plate shut.

That said, if things get too hot, alloy will even begin to migrate under the sprue plate causing flashing. So in short, it sounds like a temperature issue-- I'd let the mould get a little hotter, and if it takes a few more seconds for the bullet to "set up" without streaking, so be it.

So, from that last paragraph, you can see where chamfering the mould would be a bad idea...

[sundog]

Mugsie, how thick is your sprue plate? That is, one of the older thin ones, or the newer, thickerer one? Thin sprue plates suck for keeping relatively constant temperature. I am an advocate of chamfering block edges, but a little goes a long way. I also like a loose sprue plate, especially if it the heavier type, like what comes on the RCBS. Thick plates for Ly moulds are available in the tune up kits. One other thing, the sprue hole needs to be the 'right' size. If necessary, they can be opened up one drill bits size at a time and hand chamfered. Be sure to stone the underside for burrs, sprue plate flat on a good flat stone.

Actually, what your problem sounds like, if the cavities are clean, is a combination of heat (not enough) and venting.

If you are using the same alloy as before, and the boolits were filled out good before, then it's prolly not the alloy. If it's not same alloy, it may need some tin to reduce surface tension.

[beagle]

Stoning the mating surfaces of the top of the mould is a good ide and all my mould have this mod done to them. It insures positive venting if you have any doubts.

Take a fine stone and bevel slightly...two-three stokes. Along the top of the mould where the cavities join. Do both sides. Just enough so that you can see a slight "shine" when held up to the light. That's sufficient for positive venting./beagle

Read where someone said to use a stone to *slightly* knock the edges off the top inner (mating surfaces) of the mold blocks so as to create a small vent under the plate.

Good idea or bad?

I'm having the same issues, although many do turn out fine and keeping it hotter does seem to help. And I'm using WW and have added no tin yet, which I hear helps with fillout - is this considered a "fillout" issue? I'm adding the tin next time.

[mugsie]

As I initially stated, I cast these in the morning around 9 am or so. They were water quenched. Around 1pm I selected a batch which looked pretty decent, lubed them up with the black Moly lube from Lyman and proceeded to load them using 9.8g of Accurate's #5 powder. I shot them at around 3pm. Not a lot of time for the bullet to harden up but I was anxious to see how they would shoot. I only had 20 usable cases at the time so that's what went to the range with me. At 25 yards, off hand using iron sights and my tired old eyes, I held about a 4"-5" circle. Several were grouped within a 3" radius. In my estimation they were the best I've seen. Barrel leading? Absolutely zero. Granted only 20 rounds but the barrel was sparkling clean, something I have never seen shooting purchased cast. They were all sized to .452 and shot out of a Ruger Blackhawk convertable. This week I will cast a few hundred. Needless to say - I'm a satisfied customer. Damn I love this hobby!