Alloy / Boolits

[beng]

I know it's in the alloy, but what would make the boolits come out with a higher weight? Two months ago my 45-70 (405) were at 406 to 406.5, Now, (with a new batch of lead) it's 401 to 401.5. WHAT ALLOY WILL DO THIS?

[montana_charlie]

Your new alloy has less lead in it...or your scale has been 'recalibrated'...or you are casting at a different temperature and your bullets are not filling out as much.
(Are all corners sharp enough to 'feel' sharp?)
CM

[Calamity Jake]

I know it's in the alloy, but what would make the boolits come out with a higher weight? Two months ago my 45-70 (405) were at 406 to 406.5, Now, (with a new batch of lead) it's 401 to 401.5. WHAT ALLOY WILL DO THIS?

There are a # of things that affect weight, alloy/mold temp, rate of filling of the mold, fill pressure and a harder/softer alloy are the most common. Weather conditions can affect it too, I get better fill and heaver boolits when I cast during a rainy cool day all else being the same.
Reading your post tells me it is mainly your alloy.

[MtGun44]

Small variations in wt between batches is absolutely the norm. As the above comments
point out, temp and technique can also cause this level of variation.

Think about this, this is around 1% wt variation, a pretty darned small amount. Now
if you are trying to win a long range match, you will need to do better. I believe
Mike V our cast boolit long range expert has very tight tolerances on wt for his
hand cast match boolits, about 1/2 gr or less IIRC.

for 100 yd shooting you will be unlikely see a serious problem.

Bill

[lwknight]

A variance of a little less than 2% more tin and/or antomony can easily cause that much deviation in weight.
It is hard to keep a consistant , repeatable alloy when we use whatever we can get at a bargain.