Somewhere in my surfing I read that cast bullets harden with age. On another thread here I was told that harder bullets will run higher pressures. How soon does this happen? If I cast and load the same day, is it possible for my loads to become unsafe over time? I am currently just casting for my 45 colts and I only have around 300 pieces of brass so they last me around a month. I do not have a hardness tester but I have several boxes of commercial cast bullets. Will these eventually get so hard that they will lead my barrels?

don,t worry about the bullets getting a bit harder, Ive seen no appreciable difference in velocity or barrel leading using newly cast or even several year old bullets in ammo in my 44 mag revolver or several other calibers.
I generally cast and size and lube bullets in the same week,from an alloy of 95%-96% wheel weights and 4%-5% tin added several times a year, but ammo might not get loaded with those bullets for many months.
I use a 7 gallon bucket of water to drop hot bullets into, from my molds as I cast, and then I drain the water roll them on a large towel and dry them, I throw the few rejects back in a box to totally dry before remelting them, but I lube and size the rest after heating them with a hair drier before sizing and lubing them, and I have yet in 45 plus years to find a problem doing it that way

THIS MIGHT BE USEFUL
http://www.lasc.us/CastBulletNotes.htm

http://forum.grumpysperformance.com/viewtopic.php?f=90&t=9200

Changes of hardness that correlate to time are more a matter of alloy mix and/or hardening by a quench or heat treat process. I'd not worry much about it frankly, certainly not for a time span of 30 days. Probably over the long haul degradation of lube is a more significant issue. My primary reference for this belief is having fired cast bullets that have been loaded for quite a long period, decades actually, without ill effect. Another small point, cast bullets purchased from them what makes them....what is the alloy? You don't know and neither do I. Shoot 'em today or tomorrow...or next year.

There's some info here on the age hardening issue:

http://www.lasc.us/HeatTreat.htm

scroll down almost to the page bottom for info related to age hardening of heat treated or quenched bullets.

if you have antimony and tin in your lead it will harden to about as hard as it will get in two weeks if you water drop them.

as far as it affecting pressure, no it won't.

I have proven to my self that some loads work better with water quenched and "aged" (two weeks) bullets vs some that are air cooled aka not hardened.

You have to drop the bullets out of the mould into water and then let them set for about 2 weeks, to get them at thier hardest. Just letting them air cool even using the same alloy won't harden them.

The bullets won't continue to keep getting harder after two weeks, if you do the above.

commercial cast bullets are as hard as they will get when you get them.

I have one firearm that if I do not shoot water quenched bullets the groups are 5-6" at 100yds, use water quenched bullets and the group is 1" at 100yds.

it will take about two years for the lead to "soften" 'some' after it's been hardened.

so NO, your ammo won't become unsafe due to lead "hardening" over time.

if you're barrel is leaded it will be more due to bullet FIT in the chamber and throat, no due to hardness.

Thank you guys. I am casting with straight wheel weights. I have not water quenched any yet as they shoot just as good as the commercial cast. I don't think I need to for standard 45 colt loads. When I get molds for 9mm and 45acp the straight wheel weight should be plenty hard enough for them too, I think? Maybe if I run into a barrel leading problem some day, or get ahold of an alloy other than wheel weights I will ty it.

Don't fret about WW alloy bullets leading in the pistols you named. Head Blammer's advise re: bullet fit. If it doesn't fit properly, it'll likely lead no matter what the alloy is or how hard it is. (In fact an ill fitting hard bullet will likely lead worse than a soft ill fitting bullet.)

Dead on on all counts!

Thank you.