577611 mold. Cant win

[hocuspocus]

I read through some posts and noticed that problems similar to mine were fixed using the methods I used. That is to say that when it had bubbles inside I cranked the heat on everything and went to a dipper, but now heres the deal. It just moved those bubbles from inside up to the ogive in the form of something that looks like a small butt crack. On some its hardly noticeable. Some its sunk a 32 of an inch and 3/16" long..Any thoughts? Really cleaned and grooved vent lines, didnt help. It seems to be that I can get to hot believe it or not. Cause if I'm to cold I get the bubbles inside. As I keep heating things those go away. A few minies later and the side butt cracks start

 

[Blizzard of '93]

fluxing your melt may help get any impuritys out if that is causing a problem. good luck

 

[E Poffinbarger]

hocus:

If there is one thing about this traditional stuff that I know it is, "pouring lead". Assuming you are using pure lead, its either not clean or hot enough.

Single cavity molds are more difficult to maintain a stable operating temperature than are dual cavity molds. Needless to say, "Minies" are in this category.

My solution to achieve consistent high quality .54, 425gr Minie projectiles was to use a production pot set on maximum temperature and then hold the preheated mold tightly against the spout during the pouring process.

For what its worth, I'm not certain that I could achieve the same quality level using an over-the-fire pot and ladle.

Osage

 

[Bon Sauvage]

What they said. I am unfamiliar with that model but it sounds like you are pouring a relatively large amount of lead into that mould. Consider drilling a SLIGHTLY larger hole through the sprue plate and pour a generous sprue to go along with it. Hopefully that will prevent shrinkage voids or cracks from appearing.


Ogre

 

[paulvallandigham]

I think Ogre has the solution. Drill the hold in the plate larger, so you pour the lead in faster, to avoid bubbles.

Also, if you check with Forster Products, I believe them make a swaging die for minies, that is used with a standard single stage loading press, like the RCBS Rockchucker. You put your cast minies in the swaginging die and it squeezes them to a uniform shape, and pushes the bubbles out! The guys who use this swaging die system swear by the better accuracy they get in competition. Obviously, this would not be needed for recreational shooting.

 

[Runner]

The books say to use a ladle instead of a bottom pour spout for large conicals. They recommend a fast fill, large sprue, and that you wait a few secounds before striking the sprue to allow the shrinkage to pull more lead into the mold. Tip the mold a little to the side as you start to fill it so that the air gets out.

 

[rebel727]

I had to drill the sprue plate on my Lyman .58 minie ball mold. I wasn't getting bubbles I was getting incomplete bullets no matter how hot I got it. Only problems I've had since I did that is once I oiled my mold and didn't clean the oil off before I used it again and all my bullets from that batch were wrinkled. I figured the oil would burn off after a bullet or two but it didn't.

 

[paulvallandigham]

YOu have to clean the oil out of the mold, or it does burn and leave a residue. Its the residue that causes the wrinkles. Use either Denatured Alcohol, or Carbon Tetrachloride( Noxious, if not toxic, so be in a well ventilated area) to clean the mold. Some people find carboning the mold with candle soot, or burning a carbide lamp helps the mold cast better. I cleaned and found it would throw good balls and bullets when it got hot enough. Opening the sprue hole to make a larger sprue and get the lead into the mold faster was the key to getting good bullets consistently.

 

[arquebus]

I tend to think you still have some oil deposits left in the mould cavity & that is what is causing the nose wrinkles (do they always appear in the same spot, or do they migrate around the nose?), brake cleaner & a bristle brush should get it out ok. I cast alot of Minies (550gn .56 caliber, & 612gn .58s) & I found I get much better filled-out, & more consistent weight, bullets by slightly enlarging the pour spout on my ladle.
Another thing, wrinkles in bullets are normally associated with the lead and/or mould being too cool. Excessive heat causes a 'frosted' finish, but normally no wrinkling. The frosting isn't detrimental to the bullets performance just its looks. Are you using an electric pot? If so, I've always had a hard time getting enough heat out of them to get good quality casting with larger conicals. You might be able to 'tweak' the thermostat a bit to get more heat, otherwise I'd recommend going to a cast iron pot & a propane ring.

 

[bub524]

Couple of things from my experience with the same problem. In 30 yeras of casting minie I found you never get less then about 20% rejects. You can try a spray on mould release from Midway. It works very well and helps with filling. The larger sprue hole helps to a degree as does canting the mould when filling. Holding the mould against the spout of the pot helps. You can also loosen the screws that hold the top of the Lee production pot on. The screws around the temp controler that is. A tech from Lee told me that once. He said that would allow some heat to escape from around the thermostat and raise the lead temp slightly.
Some techniques work one day and don't the next. The nature of the beast.

 

[hocuspocus]

The ladle did er. Couldnt even find a proper casting one. Got some kinda kitchen one at a store, and theys commin out perfect. Hardly a grain diff in em. Thanks boys