Copper from Babbit in Alloys

[paborn]

Reread the info available at LASC on the use of Babbit in alloys today. Have access to some Babbit and have had problems in the past with the bottom pour spout freezing even at higher temps. There is no doubt that the addition of copper increases the toughness of the alloy. I know the composition of the material available.

Does anyone know the percentage copper that can be allowed and still get bottom pour at reasonable temperatures?

Paborn

[beagle]

I messed around with Babbitt alloys in the .223 for a while and it worked pretty well with the RCBS 22-55-SPHP and Lyman's 225415HP and 225438HP moulds. I had an unknown alloy so it was hit or miss. I sweetened a pot of WW alloy with an ingot of the Babbitt alloy and got very good results as far as allowable increase in velocity/accuracy. Up to 2600 FPS in the .223 with 1"+/- accuracy and no leading as opposed to a top end of 2400 FPS before. Same with the .22 Hornet. As I was satisfied with those velocities and accuracy and was out of Babbitt, I cast a goodly supply of .223 and rested on my laurels.

The key seems to be to sweeten the alloy with the Babbitt and be satisfied with improvement. For most of us, there is no magic alloy percentage figures as we lack the proper analysis equipment to determine the percentage of copper and the percentage of alloys in the "mother" mixture and copper has too high of a melting point to be induced into the alloy as pure copper. It has to be sneaked in as babbit alloy like Bill Ferguson's antimony alloy.

Sorry to be so vague about my methods but there are just too many unknowns for me. Kind of like making a witch's brew but it works if you accomplish it.

Felix has done it as well so maybe he'll see this and weigh in./beagle

[felix]

Beagle said it well. Copper should be no more than ONE percent of most 'mother' alloys I have used. No way to tell except by looking for a sheeting look when pouring the finished alloy back and forth between pots. If you see an envelope develop over the alloy as it is poured, there is too much copper. Too much copper will plug up the bottom pour spout in no time. So, cut the alloy in half and try again for the sheeting look. Eventually the sheeting look will disappear, and that is when the alloy is right for the temperature-pressure for the pot. Make sure the mold is up to a high temp, as with during normal boolit frosting conditions, before fielding coppered alloys. Perhaps a coppered alloy could use the PID controller to good advantage. ... felix

[popper]

Lead will only take 0.3% copper at casting temps. Babbit typically has a lot of tin so your alloy will normally be high tin, low copper. My alloy has ~ 1% Cu/1-2% Sb/0% Sn. I use a bottom pour pot @ 720-730F. Be sure to cut the sprue early till you get used to it. It sets up fast. So far 308 165 gr goes > 2400 fps - 2" @ 100.

[runfiverun]

popper uses a different method than I do and uses low tin also.
I favor a higher tin content to the alloy to help keep the copper in solution.
then cut the high tin/copper solution in with an antimonial alloy.

felix's sheeting action is an excellent indicator and if your antimonial base alloy is consistent [through big batching or certified alloy] you should have a pretty consistent copper content from batch to batch by making the first batch that way, then following the mixing weights after that.

[paborn]

Thanks. The Babbit I have I'm basically using for a source of tin. At any of the mixes I'd make, the copper percentage would be less than 1% so I think I'm OK. It will be interesting to see what kind of velocity increase I'll be able to obtain with it.

Paborn

[jeepyj]

Good bad or indifferent I've been using one and a half ounces of tin based Babbitt per five pounds of COWW for a while. I consider it to be a very successful with no leading in my 9mm,38/357 & a GC 44 mag loads. If there is more I should know I would love the hear.
Jeepyj

[runfiverun]

http://castboolits.gunloads.com/show...s-this-further
here is a little light reading.
badger EDD has another thread on the subject, and I think popper started one about a year ago on using copper sulphate to trade copper for zinc in an alloy.

[popper]

This is a good read by material science prof. http://ppt1.org/p/phase-diagrams---c...-w3002-ppt.ppt
Download the chapter 10 ppt. Not about casting, but the why of alloys. Eliminates some of the bogus rumors about alloys. Someone here indicated that the CS method would remove Sb. It won't. Sb is on the right side of H in the electrical chart so a spontaneous reaction will not occur. You add the numbers, if - Ok. if + no, can't occur. Tin & zinc are on the left side and are spontaneous in releasing free copper. Tin will alloy with copper but over time will get blobly - not good. Sb/Cu/As does not. Other studies I've found indicate that <0.1% tin does add strength to the alloy. Anymore is a waste unless it is needed to better fill the mould.

[rockrat]

I go down to about 1/3 rd percent of copper in most of my alloys. Seems like much more and the spout freezes. I have a propane torch nearby to remedy any freeze-up