Heat treat over time

[Gswain]

Been lurking on this site for a while, just recently joined. Not sure if this is the correct forum, so I apologise if it is not. I thought in my lurkings i found a page referencing lead that had been oven heated and quenched losing its hardness over time, but now I cannot find it, and it seems to go against most everything else I see. Am I crazy, or incompotent? :drinks:

[BABore]

Some here still perpetuate that old wives tale that heat treated antimonial alloys will revert back to their air cooled hardness over time. It must be a real long time as I have 4-5 year old HTWW boolits that are still at their original 28 bhn hardness. I would expect no more than a couple point in hardness reduction at most and it years. Nothing to fret about.

As a side note, I have seen some signifcant growth in diameter on any unsized HTWW boolits that are 2-3 years old. Enough growth that resizing is called for.

[btroj]

I don't sweat the loss of hardness either.

I do need to ask about the side note Bruce. How do you resize an unsized bullet? Not questioning the fact that they grow, just wondering if you had a typo?

[RobS]

BABore has actually sized them once and then after time had them grown on him so he had to resize to have them "fit" his cylinder throats (revolver). Others have had the same thing happen as well.

[BABore]

BABore has actually sized them once and then after time had them grown on him so he had to resize to have them "fit" his cylinder throats (revolver). Others have had the same thing happen as well.

Nope! Just the opposite. I had a batch of HTWW boolits where only half got sized and checked. After a few years I found that the sized boolits stayed at sized diameter whereas the unsized ones grew a few thousandths.

[RobS]

Nope! Just the opposite. I had a batch of HTWW boolits where only half got sized and checked. After a few years I found that the sized boolits stayed at sized diameter whereas the unsized ones grew a few thousandths.

Well maybe it was gear then that said something about sizing, loading and then not being able to chamber his rounds. Water quenched, I am seeing the same results with no or little growth on my sized bullets but there is some growth happening with the ones that are unsized though.

[btroj]

Thanks for clearing it up Bruce.
I have to wonder how much a change in BHN is enough to matter? Can you really tell a difference in shooting between 20 or 22?

[cbrick]

Thanks for clearing it up Bruce.
I have to wonder how much a change in BHN is enough to matter? Can you really tell a difference in shooting between 20 or 22?

No, not really. I did a huge amount of testing BHN several years ago. A minor difference in BHN made no difference in grouping with a long range revolver. If the BHN of the bullets within a 5 shot group is within 1 or 2 BHN ( a minor BHN difference) all is well.

What does open up a group is a wider spread in BHN within the same group, say mixed bullets running 15 to 22 BHN (a big BHN difference) within the same 5 shot group and groups head straight off to haitis.

So consistency is a good thing but a minor BHN difference didn't make any difference in my 150m and 200m revolver tests.

Heat treated bullets do age soften but with a catch. The catch is that none of us on this forum will live long enough to see a change worth noting. I tested 10 year old heat treated WW alloy, 30 BHN when stored at room temp. 10 years later they tested 26 BHN and in all probability had hardness stabilized well before the 10 years was up. By 2075 or so (Obama will be gone by then :mrgreen:) they may be 20 BHN or so.

Rick

[Gswain]

Thanks for the clear responses everyone, that really helps! I actually found where I read that, it was on the LASC guide, seems that the higher the imbalance between tin and antimony in the alloy, the more likely that the bullet will soften with age if it was heat treated. This forum is awesome!

[Diegokid]

When I cast I have a five gallon bucket full of water sitting beside me. For ease of use I inttalled a stopper at the bottom of the bucket. I cut the lid out and lay an old rag/towel whatever with a slit in it across the top and snap the lid over that. When I drop bu casting they roll through the slit and are cooled. DO NOT LET ANY LIQUID IN THE SMELTER, EVEN SWEAT!

Anyway what I have noticed is that these castings definbately get harder after sitting a few weeks or months. If I size and lube them within a few days they are easy, if I wait a few weeks or more it does take more effort to size them.

[MikeS]

When oven heat treating boolits, is it better to size them first, then HT, or size them after HT? I would think it would be better to size first that way the heat treating isn't disturbed by sizing (work softening) the alloy. And I would think it would be easier to size before being treated because the boolits would be softer. Of course this doesn't apply to water dropping, unless you're fast enough to size them as they fall from the blocks, and before they hit the water! :)