alloy was hard to cast with

[bmortell]

I mixed 5lb of magnum shot ingots 2% tin already in it from 95/5 wire, with 4lb cow ingots and some more soldering wire, except this wire was 95% tin 4% copper 1% silver. and it didn't cast very well, high reject rate from poor fillout even when frosty and bubble voids around the base were common. I know the cowws are fine cause I always use em and used the same mold the previous day with different alloy, does anyone know if the copper containing wire is bad for casting or the mag shot and overall high arsenic content ?

[Winger Ed.]

I use old partial rolls of 95/5 all the time, and they work fine.

That mix sounds like you'll end up with boolits about as hard as Chinese Algebra.
I'd thin it out about 50% with pure lead and try that.

50% wheel weights, and 50% pure lead is kind of a favorite, go-to alloy with the folks around here.

[Dusty Bannister]

Was the bubbles around the base from the alloy or from sprue plate lube? Doubtful that the arsenic has any affect on the casting. Copper might migrate to the nozzle and slow the flow and result in cooler alloy going into the mold. Dip or bottom pour? You did change the alloy when you added the copper, but I would not expect it to be enough to change the casting conditions unless you were already casting on the cool side. Melt temp at 725 or less? Ambient air temp or a breeze could also have an affect on the alloy flow. Magnum shot might be about 6% antimony but you said ingots made from shot so the graphite or oxide should have already been removed in fluxing the melt before you poured the ingots.

[bmortell]

ya I oven heat treated at 425 to make some very hard boolits, it was my goal for the afternoon

[lightman]

Thats a harder alloy than I usually cast with but a higher pot temp might help. You said you used the same mold recently but was it clean and oil free? Low temps or contaminated mold are the only things that come to mind.

And occasionally you just have days that nothing goes as planned?

[bmortell]

maybe it was just a bad casting session, but I hadn't oiled the sprue plate or changed anything with the mold in several sessions, and I was going at a temp and speed where bullets were all medium frosty so it seemed weird that fillout was the problem.