Casting problems with minie balls

[blackpowderbill]

How can I get my .575 Minies to cast without wrinkles and voids? When casting RBs I have no problem but when it comes to minies, I get more rejects than good balls. Usually the flaw will be on the skirt and around the base plug. I do not believe this is a tempature problem as I have tried setting my pot at different temps with no improvements. I am using lead flashing and lead caulking , it is all very soft and yeilds to the fingernail test.
Any help will be greatly appreciated.

[Ladobe]

Never casted minnies, closest was maxiballs, so can only suggest from experience with the maxiballs when I first started casting them decades ago and I had similar problems, FWIW.   
Possibilities... a temperature problem with the mold blocks themselves, dirty mold blocks, or impurities in the lead (dross, etc) might be worth checking out.

[quickdtoo]

With larger projectiles, it always takes a lot longer for the mold to get hot, that's always been the solution to get nice bullets/balls, keep running lead through the mold, eventually when it gets up to temp the wrinkles and voids will disappear. I always preheat the mold on top of the pot so it and the lead come up to temp together, same for any lead I add to the pot, preheat it so it doesn't cool the pot too much when added. 

Tim

[Odinbreaker]

Get a thermometer I keep the temp about 850 to 900.   Keep your mould at a constant temp.  I found a colder mould will give voids and to hot will cause wrinkles.   Try Cast Boolit web site for good advice on casting.

[wiley]

Just a guess, but if you're using the Lyman mold with a separate base plug, it's important to keep the plug hot between pours. Some casters use a separate heat source  or touch the plug in the melt before a pour.

[blackpowderbill]

Thanks for the input. I shall give some of those ideas a try this weekend.

[Hellgate]

I get less rejects if I run the lead temp real hot and I put a lot of lead in the bottom pour pot where there is a good, fast flow. Also I weight them after I'm done and end up with some more rejects due to internal viods.



I saw a plastic bag at a sporting goods store with cast minies for sale and couldn't believe the number of voids there were inside the hollow bases. Most of the bag would have gone into the melt pot if they were mine.


Also I found that I needed dead soft pig lead to get the best performance from the heavy skirted minies I used for deer & elk. A thinner skirted minie might be OK with heavy charges if the alloy was slightly harder than pure lead. If your lead sheeting is a little harder you might find a heavier charge might be needed to swell the skirts.

[blackpowderbill]

I cast some balls this week. The first thing I did was to scrub out the mold with 90% alcohol. My first bullets were good then the problem returned. I finally realized that when I set the base plug down upon the pine surface so I could drop the bullet from the mold, it touched the wood surface which was contaminated with oil. That little bit of oil was causing me all the heartache.