Optimum % Tin in Alloy?

[Boyscout]

I have been mixing 2% Tin in my WW/-70/30 (Lead/Antimony) alloy and getting pretty good results. What is the optimum % of Tin for castability before I start reaching a point of diminishing returns?\

[Idaho Sharpshooter]

are you saying 70% lead/30% antimony?

[fryboy]

i believe he's referring to a mix of ww and roto metals super hard ( it's the 70/30 part ) ...

ummm we can only guess actually as we dont know the final alloy nor the desired/intended usage , ...2% sometimes is more than i need other times not enough yet one has to but recall that elmer kieth's fav alloy for the 44 mag was 16/1 ( Pb/sn ) with no antimony - and it worked well for him and many others , 16/1 is roughly 6.25% , another factor is if you heat treat because if you do the tin works detrimentally against it , especially over longer periods of time ( it tends to revert to softer ) i also recall of folks casting an shooting pewter boolits ( ie; almost pure tin ) IF you're having problems with fillout add some IF not save the resource [shrugz]

[runfiverun]

2% is enough, after that you gain nothing except a longer/stronger SbSn chain in the alloy.
but even that has a limit.
i add at most 1% tin to my ww/soft 75/25 mix ,i usually add less than that, more like .50%.

my other alloy is 4/6/90 but it only has some specific uses.

[shadowcaster]

Speaking in General terms... I try really hard not to add more than 2% to any alloy. If I can get away with less than that, or even none at all, all the better. Tin is expensive, so why waste it if it's not needed. Some combinations of particular molds and certain alloy just need tin added, others don't. Once I find the right mix for my needs, I stick with it. Try using less tin and see how it works out...

Shad

[Defcon-One]

I use 2% Tin for all of my handguns loads (2% Sn, 3% Sb, 95% Pb)!

I use 5% Tin for all of my rifle loads with gas checks, Lyman #2 (5% Sn, 5% Sb, 90% Pb)!

It works great for me and both alloys have excellent castability. Better yet, I only need to keep two alloys on hand.

I also have a stock of 60/40 Solder and Linotype strips. But those are just for alloying.

[Boyscout]

I have been using the 70/30 Lead/Anitmony from Rotometals. I cast a few Lee C312-180 while trying to achieve a 16 BHN. I did an Excel calculator based on the 70/30. I water quenched some and air cooled others to test them and see what difference it made. I have tried to melt some pure antimony but had trouble getting it to melt. I did see a thread that talked about "disolving" it in tin before adding it to the alloy. I hate wasting expensive tin on an experiment.

[Defcon-One]

Everything that I have read says that 2% Tin is optimum. In normal situations, no more than that is needed. Many get by well with 1%, the cheaper route.

At those amounts, it is not all that expensive and it really improves the bullet quality and mold fill out!

I am not a fan of water quenching or super hardened bullets!

[Boyscout]

The 16 BHN is for Mosin Nagant and a Springfield 03A3. I may eventually buy a .358 200 gn FP mold to shoot out of a .35 Remington Woodmaster 760. I also shoot .45 ACP, .38 Special and .357 Magnum. I want the bullets to shoot well and not lead. Hunting opportunities are limited for all except the .357 Magnum in Indiana.

[Le Loup Solitaire]

Generally, adding 2% tin to wheelweights that have some antimony in them will make an alloy that flows well, is harder in BHN and yields pretty sharply filled out castings. It can be increased to a point where it comes into the range of Linotype and that has a Brinnel/BHN rating of about 22. That's pretty hard stuff. There is a graph shown in the first edition of the NRA Handloading book which depicts the addition of tin and antimony into a lead mixture and it clearly shows that continuing to add tin past a certain percentage has no further effect on hardening the alloy. It would be pointless and wasteful to do so; tin is expensive nowadays...certainly moreso than yesteryear. So some sensible planning and use of it to improve the fillout and hardness of our bullets would be the logical way to go. LLS

[Boyscout]

Here is the results of my last effort to reach 16 BHN:

Air cooled: 15.4 BHN
Water Quench: 20.1 BHN

This was measured with a Lee Hardness Tester. My formula starts with the BHN hardness of my batch of wheel weights, 2% tin and calculates the needed 70/30 to achieve the desired hardness.

BHN (desired)=BHN (start) + X(70/30)+BHN (Tin)

My batches have been small so I am hoping to get closer to the goal going to 20lb. instead of 10 lb.

[GRid.1569]

I recall reading somewhere that going beyond 4% was a waste.... perhaps that was from a hardness perspective...

For sure though adding more tin just adds to the cost of your metal... based on that I'd stick to around 2-4% for good fill-out....