Antimony alloy

[kokomokid]

I know at least a couple of guys here use a touch of antimony and maybe there is a secret to cutting the sprue and getting a smooth bullet base. Where I get a slick bullet base with lead tin alloys adding just a small amount of antimony tends to pull a little metal from the bullet base. What should I try?

[Bent Ramrod]

Once the mould is up to temp, I turn it over after filling and press the sprue plate and puddle against some sort of heat sink for a few seconds.

I used to use a damp wad of rags, but the water would evaporate before the casting session finished and the sprue plate would begin to get rusty. Now I have a large drippings pan (or something) bought from Goodwill that I use to contain the mess around the casting pot. I touch the sprue plate and sprue against the rim of this for a few seconds.

[Chill Wills]

I know at least a couple of guys here use a touch of antimony and maybe there is a secret to cutting the sprue and getting a smooth bullet base. Where I get a slick bullet base with lead tin alloys adding just a small amount of antimony tends to pull a little metal from the bullet base. What should I try?

Do you think you are having accuracy a problem from the rough circle in the base? I use more than a "touch" of Sb in my mix. I too was concerned but got over it when I saw no difference at the target.
One thing I would advise is to not use lesser amounts of Sb in a tin lead mix. Small amounts of Sb in the mix can cause hardness fluctuation. I have a dozen or more samples of different metal mixes I track and chart for hardness over time.
If you are going to use a three metal alloy, Pb, Sb, Sn, exceed the amount of Sn with the Sb. A good mix by percent is 98 - 2 - 1, Pb - Sb- Sn. Variations of that are in use and produce harder or softer finished alloys. The one cited will hold the nose on the long nose high Bc bullets in use today.

Good luck and you may not need to worry about that less than smooth cut off if you do not see accuracy issues. We have bigger things to control

[kokomokid]

Thanks, I tried a damp towel and still pulled some metal.
Will weigh a few and see how well they shoot. I have a bar of lino as well as a bucket of cww I can try. What I was using was 95/5 solder at 17 to 1 and thought that slight amount of antimony would cut slick. Agree we have bigger things to control.

[Hiwall55]

I have been using SOWW at 25:1and have been having good luck with my money bullets. Cutting the spruce and shooting well to the Ram line.

[Lead pot]

I use a mix of antimony and it has a tendency to tear the cut. It is cosmetic but I never seen it a problem with accuracy.
There is a way you can make a clean cut with out tearing a hole.
Making the cut to soon before the alloy is set. The alloy is like putty till it sets even if the puddle is gray the bullet in the cavity is still soft.
Some moulds come with a hole in the plate much larger then is needed for a good fill with a sharp base edge. This can also pull the bullet base away from the mound even when the puddle is gray. When I order a mould I request a sprue plate with a .100" hole like the mould in the photo has. That is more then enough to get a good sharp base.
With a plate with a large hole I put pressure down on the plate and with a wood dowel and push the plate, not hit it to make the cut. I also use a tight plate that will not swing freely.
That bullet in this mould is a mix of 18 lbs lead and a 1 lb roll of 95/5 no lead solder, 95% tin/5% antimony in that one pound roll of solder. That is enough to hold the ogive setback making it look just as good as one that has not been shot.


IMG_2914 by Kurt, on Flickr

[kokomokid]

Thanks Kurt. Looks like only way to get small hole plate for a Saeco is to make it.

[Lead pot]

That mould is a KAL mould.