Can Lead be "Too Pure" to cast?

[Jayhem]

So recently I set out to cast up a few hundred muzzleloading boolits as the deer season for front loaders starts here Oct 30.

I usually cast my muzzleloading boolits from my 500 lb stash of old chilled lead shot but this year decided to try the pure lead sheets I had been given years ago but never smelted them down...it's tough to melt down sheets of lead, have to cut them into pieces first with a hatchet!

Anyway I finally got a nice smelt of this stuff going, got the mold up to temp, metal up to temp and started casting. 20-30 casts came out wrinkled with sprues that would not let go of the sprue plate and I was sure the metal was plenty hot, and I had fluxed it twice! I was left scratching my head. I have casted thousands of boolits with this mould, never had this happen. [smilie=f:

I'm no expert to boolit alloys but I remembered hearing that tin helps the metal flow better so had purchased a few sticks of it from rotometals a while back.

I put in 1 ounce of tin to my 5 lbs of metal, fluxed it again and instantly...PERFECT BOOLITS! I cast 150 last night and not one of them had to be returned to the pot. :-P

There is no question tin made the difference. I'm just wondering WHY my pure lead melt would not throw a single good boolit? Any ideas?

[docone31]

A lot of factors here.
Tin, and I have some on hand, can really help. I rarely use it, but it is there if I need it.
Again, a lot of factors. Oxidation on the sprue plate, not getting the melt hot enough, lots of factors.
Good luck on the hunt!
Sounds like deer to me.

[fecmech]

If you were getting wrinkles you weren't hot enough. Casting with straight lead requires fairly hot temps in the high 700 degree range. If you don't want to use the tin, crank up the heat.

[Echo]

One ounce of tin with 80 ounces of Pb gives a little more than 1% Sn, and it is amazing what that 1% can do! It's my understanding that, while Sn adds a touch of hardness, it mainly reduces the surface tension of the alloy (and interacts nicely with Sb, if that is present) making for good mold fillout and behavior.

[Jayhem]

A lot of factors here.
Tin, and I have some on hand, can really help. I rarely use it, but it is there if I need it.
Good luck on the hunt!
Sounds like deer to me.
Yes, blackpowder deer season in Virginia is 2 weeks long and before rifle season and in the height of the Rut! It's the best chance to take a large buck but the deer are so overpopulated here they let you take 6 deer a year now and either sex full season! Got 4 last year. Just finished the last of the venison. [smilie=s:



If you were getting wrinkles you weren't hot enough. Casting with straight lead requires fairly hot temps in the high 700 degree range. If you don't want to use the tin, crank up the heat.
I was thinking it has to be the temp but I cranked it up as high as it goes and still wrinkles till I added tin. So tin allows the temp to be lower?

I heat my metal on an outdoor propane burner using an iron pot so perhaps it just won't keep the metal that hot if there is any breeze. :shock: I just remembered it was a bit breezy when I did my casting. I think you nailed it! Man I was getting so frustrated!

[Jayhem]

One ounce of tin with 80 ounces of Pb gives a little more than 1% Sn, and it is amazing what that 1% can do! It's my understanding that, while Sn adds a touch of hardness, it mainly reduces the surface tension of the alloy (and interacts nicely with Sb, if that is present) making for good mold fillout and behavior.

The mold fill out was unbelievable, razor sharp edges, I've never cast such good looking boolits without tin. Also the ease of the sprue falling off cleanly was a miracle from it's previous behavior. Thank you, tin.

[GP100man]

Pure lead is like a cricket on water , the tension is what keeps him floating until he breaks it .

The tin lessens that tension in lead & lets it relax to fill the mold

[idahoron]

I use 1000 grains of chilled lead shot to 10 pounds of my pure lead to get it to flow better. It does not add to the hardness much at all. I know that my rifle does not like pure lead at all. It likes about 7 BHN to 8 BHN. Ron

[cajun shooter]

Your old chilled lead shot if Factory made contained either arsenic or antimony or both so that is what was making your casting easy and the mold filling out. When you switched to pure lead no deal. The shot runs about 8.5 BHN as pure runs 5 BHN

[crabo]

I heat my metal on an outdoor propane burner using an iron pot so perhaps it just won't keep the metal that hot if there is any breeze. :shock: I just remembered it was a bit breezy when I did my casting. I think you nailed it! Man I was getting so frustrated!

Get a piece of sheetmetal to make a windbrake around your pot. It will hold your heat in. I used a couple piece from Home Depot that I pop rivited together for my smelter. Mine is just a section of flue.

[montana_charlie]

The mold fill out was unbelievable, razor sharp edges, I've never cast such good looking boolits without tin.
Once you have seen those razor sharp edges you can never be satisfied with bullets that don't have them...especially on the base corner.

You see a lot of pictures posted of bullets that look pretty good...but you can tell by the way light reflects off the corners that you would (now) call them rejects.

CM

[Jayhem]

Get a piece of sheetmetal to make a windbrake around your pot. It will hold your heat in. I used a couple piece from Home Depot that I pop rivited together for my smelter. Mine is just a section of flue.

Excellent idea. 8-)