Babbit Analysis

[fordfan]

Last year some time a good buddy gave me a 5 pound bar of McMaster babbit and not knowing the make up of this stuff I just kept it laying around. Well finally I had my neighbors brother who works for the old National Lead Plant analize it for me and it came back as 77.3% lead, 5.8137% tin, 14.9085% antimony, .06870% of AS and a few more minor ingredience. Now I can finally use it. Plus as a side note he gave me a 3.6 pounds of pure Tin. Its been a good day.

[madsenshooter]

I have used a similar alloy for some high velocity work, but, that much Sb makes for a brittle bullet that'll take around 35000psi tops. When lead blows back on the caseneck, you know you're over the alloy's pressure limit. Ask your neighbor's brother what the formula is for National's Heavy Pressure babbitt.

[fordfan]

With this babbit how much pure would I have to add to bring it close to a coww consistency.

[RogerDat]

Lead alloy calculator from the sticky is your friend. Place there to enter custom alloy such as your babbit then add other materials and get percentage of each material with BHN expected from your mix. Hit the last page of the sticky and work backwards to download the most recent version.

Using it I come up with 35# of plain lead to 10# of your Babbitt would be very close to COWW with 1.29% Sn and a BHN of 12. Not knowing the "small amounts of other" things the calculator rounded the Pb to 79% instead of 77% you stated. You would be without Arsenic which would matter if you wanted to heat treat for harder bullet.

Calculator is one darn useful tool well worth downloading. Really I would hold onto that Babbitt and use it to sweeten a batch of COWW or some other lead where you wanted to yield a bullet for a magnum load where the hardness would be worth the value of the Babbitt.