92-5-3 should cast good boolits right?! Not for me so far

[old_haidouk]

A few friends and I pooled and got a deal on 1500 lbs of foundry lead. It is 92-5 antimony-3 tin. It should be perfect for low to medium velocities we thought. We use Magma molds on a master caster and the bullets come slightly out of round and unersized. Or even when they are not out of round they're still undersized. They only drop .0005 to .001 over the sizing die diameter. Is it the alloy or is it something we re doing wrong?

[ANeat]

Out of round is a mold problem, undersized could be mold or alloy.

A mold should be cut to drop whatever size with whatever alloy. (say .359 with 92/6/2) Change the alloy and the size will change..... If the sizer cleans them up I would be happy with .001 over size.

Cast with another known alloy if you have sonething available and compare size/weight

Your 92/5/3 mix should make a real hard bullet

[lwknight]

Undersized compared to what?
Maybe the other alloy was oversized?
What I'm getting at is that there is no real standard to compare molds and what is expected from each different manufacturer.

The Magma molds are probably rated for 2-6-92 alloy. And no molds are exactly perfect to boot. I don't see the problem if the bullets are sizing to the desired size.

You could probably mix in half again pure led and still have a great alloy for medium to heavy pistol loads. You did not mention the cast size . The larger the bullet , the more profoundy the shrinkage of different alloys can be compared.

[runfiverun]

speed up the casting forget the 15 seconds they tell you.
if you aren't heating the mold up and getting a lead smear once in a while you aren't going fast enough.
pour, lower the handle a bit ,as soon as the color change takes place open the handle.
you can usually see it happen under the spout.
when i got my first master caster i wanted to watch everything too.
never mind that just find your rythmn and cast you can turn the pot temp down a bit once you get the mold up to temp.

[old_haidouk]

By undersized I mean .0005 to .001 bigger than what I want to size them to. Magma says a 9mm bullet will drop from their molds at .357-358. With my alloy they drop at .3565-357 Ijust don't know if the alloy I use 92-5-3 should make that much of a difference over 92-6-2. Or maybe I just don't get the mold hot enough. I do see a bit of frosting between the mold halves on the bands and lube groove. Can't figure this out.

[runfiverun]

if the rest of the boolit is shiney and that part is grey [not whiteish and rounded] flat grey like galvanizing,. thats fine, and you want the rest of the boolit to get that color.
i'd be a bit more concerned about them not coming out at 357 or so.
now if thats what is concerning you as many 9mm's want a 357 or 358 boolit to shoot their best.
i would look at giving the mold a lapping.
it will open the cavity to round and make the boolits fall from the mold better.
you may not want to open the nose, and you can certainly round it out too if it's off a bit.

another thing to look at is how you have the guide rails set up, if they are too tight, or set up unevenly, it will affect how the mold is held closed.