Miminum amount of tin needed with WW's?

[Vulcan Bob]

Hi all, I am just getting geared up to start casting again and am wondering what is the least amount of tin to add to wheel weights to help with mould fill out? I plan to smelt in twenty pound runs and as for the moment buying tin seems a bit pricey but will do so for startup. When the flea markets and such reopen in the spring I will be scrounging for pewter!

[docone31]

I used tin once.
If you heat the mold, you won't need it.
The sprue should take six seconds to freeze. Longer and the mold is too hot, less time and you gotta add heat.
Save your money.
Heat it up.

[Larry Gibson]

No, you do't "need tin" with a lot COWWs. However there are some batches in some parts of the country that almost have no tin in them. The tin does definately helps with "fillout" but the primary reason to use tin is it makes the antimony blend in better in solution with the lead. This results in a slightly harder and more uniform alloy in your cast bullets with out "spots" of antimony that can cause non fillout and give antimony wash in the barrel. I've found over the years that anywhere from 1 - 3% tin is needed depending on the quality of the COWWs used. I generally advise to add 2% tin as that works almost all the time. A lot of complaints are generated about a couple makers of moulds because they cast too small in diameter (i.e. they do not "fill out"). This has so far, in my experience, been the result of the use of straight COWWs and probably some incorrect casting technique.

Tin may seem expensive but 2% tin added to 20 lbs of COWWs is only about 6.4 oz of tin. There are alloy calculators around that will give te exact amount. Anyways a 1 lb bar of 50/50 solder will "do" 30 lbs of COWW alloy nicely. Depending on the bullet that can be a lot. The 50/50 solder can be scrounged as can pewter but I find it easier to just buy the pure tin. The cost of the tin is reasonable to me because not only do I get much better alloy and thus bullets but adding the tin to the COWWs reduces the frustration of lots of rejects and poorer quality cast bullets to shoot.

If you want to get quality alloy and thus bullets from your COWWs then add the 2% tin. Let the bullets AC for 7-10 days for a BHN of 14 - 17 depending on quality of the COWWs. The batch I have now is giving me a BHN of 15-16 and casts excellent bullets. regardless of the mould used.

Larry Gibson

[MBTcustom]

For the most part, I agree with Larry Gibson's post above.
The rule of thumb with tin is "you only need it when you do, and even then, only as much as you need." LOL

I have experimented with lots of different tin alloys because I have quite a bit of it.
After trying this that and the other over the years, I have found that if I hold my head right, I can get near perfect results from strait COWW that have no tin, 1.5% antimony, and some other junk that makes them harder like nickle and copper (just a sniff).

COWW alloy is not lead, antimony, and tin like everybody likes to think it is. It is a Heinz57 that covers half the periodic table. The only element that seems to be of significant percentage across the board (other than lead) is antimony. The tin comes and goes and may be as high as 1.5% but that is the exception rather than the rule in my book.
If you want good fill out, I would agree with Larry that about 2% is plenty good kemosabe. I consider Lyman #2 (90/5/5) to be a glorious waste of valuable metal just so you don't have to concern yourself with learning about the principles of proper fit LOL.
Just be sure not to add too much tin to the mix.
If I were you, I would figure out how much tin you would need to add to bring it up to 2%. Weigh it out and set it to the side. Start adding in to the melt, little by little. Add a little, flux with sawdust, stir, and cast a few boolits. Observe your fillout and the look of your boolits. Keep throwing them back into the pot as you cast them. Keep doing this until you use up all of the tin that you had rationed out for this batch. If you are still having problems after adding all the tin, then rest assured you have something else going on other than tin content. Perhaps your technique needs improving, or perhaps you got a zinc WW mixed in there.

[fredj338]

Agree, you probably don't need any tin, but adding 1/2% by weight to the pot will almost always make for better mold fill out & not break the bank.

[Vulcan Bob]

Thanks for the info all! I havent cast a boolit for twenty seven years and I definitly need "recertified". I have just about everything I need now and am waiting for better weather to start smelting outside. I got about 1,200 lb of clip on wheelweights saved by a garage owning buddy of mine around twenty years ago who used to cast so there should be little to none of the dreaded zink monsters in there. Things sure have and havent changed since then!

[Larry Gibson]

"I got about 1,200 lb of clip on wheelweights saved by a garage owning buddy of mine around twenty years ago"

As you suspect that is probably a very good batch of COWWs! Adding 2% tin to those will probably give you an AC'd BHN of 16-17 which will make them very good for a lot of different cast bllets. You can stretch the COWWs by adding lead then for many handgun applications.

Goodsteel is absolutely correct with;

"COWW alloy is not lead, antimony, and tin like everybody likes to think it is. It is a Heinz57 that covers half the periodic table. The only element that seems to be of significant percentage across the board (other than lead) is antimony. The tin comes and goes and may be as high as 1.5% but that is the exception rather than the rule in my book."

This is why there are "good" and "bad" batches of COWWs. It is why some get excellent bullets with COWWs and others get miserable cast bullets with their batch of WWs. It is also why adding the 2% tin is a good all around idea. Even then we will come across a batch of COWWs that just is bad and little you can do to make it cast good bullets. I've run across a couple such batches in 40+ years of casting. One was unsalvageable regardless of what I did to it. I traded it to a fisherman who had an excellent batch of COWWs he was using for sinkers. The other batch was salvageable by adding 3% tin and about 30% lead. Thise gave serviceable pistol bullets for my slower .38 SPL, .44 SPL and .45 Colt loads. Sometimes a batch will be a rock instead of a diamond regardless.......

Good find on those 20+ year old COWWs.......

Larry Gibson