Base not filling out

[DHurtig]

I have a Lyman 225438 that I used for the first time this weekend. I had a number of bullets that the base did not completely fill out. I was using two molds at the same time. The other was a Lyman 225415 and the bases filled out nicely. Both are 2 cavity molds and I was using straight WW. I'm puzzled why one filled out nicely and not the other. I have the small Lee pot that holds about 4 pounds of lead and filled the molds with a ladle.

Is this a problem with the mold, or do I just need to add a little tin. I have some monotype that is supposed to have more tin. If this would work, how much should I add. Or..... since the 225438 is a gas check mold, would this affect the bullet once the checks are in place.

I've lurked here for quite some time and have gleaned a wealth of information from the members here. Thanks for all the help you have unknowingly given me in the past and I hope you can help me here. Dale

[Jim Flinchbaugh]

There is a lot of way smarter people here than me, but I found, that with my molds, the sprue plate needs to be hotter to get the base to fill out good. ( all I have is 'luminum molds)

[runfiverun]

it works that way with steel ones too.
i have the rcbs 0-55-sp, i have to start it hot and cast very efficiently to keep it that way.
i don't even let the sprue go from liquid to full solid before opening it.

[bdoyle]

I think I would try pouring a bit more lead a bit longer. That will make sure the plate stays hot. Not as neat and you pour back more lead but good bullets are more important that tidy sprues.
Brian

ps - any idea of lead temperature? I had better luck with the 22s running fast and hot.

[JeffinNZ]

Marry the mould. My experience is when you marry something the 'base' tends to fill out rather well.....


Seriously though, all moulds have likes and dislikes. My .22 moulds like to be force feed with the ladle held agaist the pouring hole. Other moulds like the lead poured in from 2 inches above the plate.

[DHurtig]

I don't have a thermometer , bullets are shiny but just beginning to look frosty. I'll have to try for bigger sprues and see if that helps. Dale

[220swiftfn]

Marry the mould. My experience is when you marry something the 'base' tends to fill out rather well.....

Now that there's funny............ Or at least it would be if it wasn't so close to the truth........


Dan

[BulletFactory]

I have a mold that if the plate is too tight, or too lose, it will do this. I bring the screw to snug, and back it off 1/2 turn.

[kappy]

Some things to try...
1. Make sure the sprue plate is hotter (by pouring some lead over the top).
2. Pour slower.
3. Pour faster.
4. Put the very bottom of the mould in the lead (making sure it is completely closed) to get it heated all the way through.

I'm no expert, of course... but I hope it works.

[geargnasher]

I don't have a thermometer , bullets are shiny but just beginning to look frosty. I'll have to try for bigger sprues and see if that helps. Dale

Shiny/frosty is entirely a function of the MOULD temperature, not the ALLOY temperature. Frosty means hot mould+antimony in the alloy, shiny means cooler mould. Alloy temp makes no difference except it gets the mould hotter faster for a given casting cadence, and if you get your alloy over 750F you increase dross formation exponentially and completely negate any benefit of having tin in the mix.

If your bases are rounded, make sure your sprue plate is plenty hot (pour a big puddle, like nickel sized at least), make sure you're filling the cavity quickly enough (don't just dribble the lead in there), and check your sprue plate for being too tight and the vent lines at the bases of the blocks for clogage.

Gear

[Linstrum]

I concur with geargnasher, he has good advice on the problem.

The usual reason why the base doesn't fill out is because of trapped air since it is difficult for air to get forced out of sharp corners by the liquid metal. Basically, the sprue cutter acts as a lid that helps trap air at the boolit cavity base, and the way I solved the problem on particularly troublesome molds is to cut new vent grooves in an "X" that is centered on the sprue pour hole on the underside of the sprue plate. I use a regular hacksaw blade and I'm guessing the groove dimensions are about 0.050" wide and about 0.010" deep. When that shallow the grooves don't cause corresponding ridges on the boolit base. A good sharp base and gas check crimp heel are important to get uniform weight from one boolit to the next, plus keep gas checks from blowing off.

rl 1084

[geargnasher]

Linstrum, don't you wish every mould had the vent lines cut in the top like Bruce used to do? That was a super idea and I've beveled blocks and filed cross-vents in the top of more than a few of my other mould brands, it really helps minimize the base voids too.

Gear

[Linstrum]

Yup!

rl 1085

[ku4hx]

Marry the mould. My experience is when you marry something the 'base' tends to fill out rather well.....

Ooooohhhhh ... reminds me of a joke about toilet paper .............

[44man]

Linstrum, don't you wish every mould had the vent lines cut in the top like Bruce used to do? That was a super idea and I've beveled blocks and filed cross-vents in the top of more than a few of my other mould brands, it really helps minimize the base voids too.

Gear

Yep, and is why I leave end mill marks on both the mold top and sprue plate.
Nobody mentioned to take a fine file and break the sharp edge at the top parting line.
I keep a propane torch on the bench and a few passes on the plate does the trick too.

[Jim Flinchbaugh]

Ooooohhhhh ... reminds me of a joke about toilet paper .............

Worked on your butt didnt it?

[beagle]

Bevel the block tops and try casting a little faster. The 225438 is a very small little booger and doesns't heat the blocks very fast. It was almost take casting as fast as you can pour to make god bullets./beagle

[madsenshooter]

I'll bet there's a difference in the tension of the sprue plate between the two molds DHurting. As others have said, temperature is also a factor. I have a Belding and Mull 311169 single cavity that throws some with the base square, some with the base rounded. I just sort em into two piles after I'm done. I think the sprue plate could stand a little microventing like NOE does to theirs.

[40Super]

A Lyman 120gr 358 mold that that I bought a couple months ago does that badly with one cavity, the one right next to the sprue screw. The outside cavity,no issues whatsoever. I honed the parting line edges a little and it definately helped, I am going to hone a little more, I figured that is where the sprue is the tightest and not allowing air movement.

[DHurtig]

The sprue plate on the problem mold is tighter. I'll try backing it off half a turn. Dale