Heat Treatment and Powder coat

[archeryrob]

I was reading about heat treatment being more consistent than water dropping. SO I cast a bunch for 6.8 and air cooled them as I can inspect them better and back in the pot while casting for all the rejects. I have always water dropped and powder coated and water dropped from the oven again.

Everything I read seems to be for lubed bullets. I can sized, gas check and heat treat. Or heat treat and size. When can I powder coat and is doing them at 400 going to drop the hardness? I have not been able to read yet how to incorporate powder coating into the heat treatment.

[Dusty Bannister]

Result of "advanced search"

https://castboolits.gunloads.com/showthread.php?255896-Oven-treating-powder-coated-bullets&highlight=heat+treating+powder+coated+bullets

[archeryrob]

Thanks, I heat treated the lot today. I sixed them before doing anything. Save one air cooled, and one heat treated for hardness testing later on. Washed all the bullets to get the sizing lube off and drying on a towel in the basement now. Unless it get warm and the air conditioner lowers the humidity, there won't be any shake and baking powder coating getting done. 55% humidity here inside and thats a no go.

[More_Slugs]

Heat treating won't make them soft.

You'll heat treat for an hour, then water cool.
Higher temp heat treatment with water cooling at 70F makes for harder bullets.

Here's detailed information, with heat treatment and water temps, and the hardness over the span of a 2 week cure:

http://www.lasc.us/heattreat.htm#chart

[bmortell]

i take the tray of powder coated out of the oven and throw the whole tray quickly into a bucket of water. if doing that theres no point of water dropping from mold

[More_Slugs]

i take the tray of powder coated out of the oven and throw the whole tray quickly into a bucket of water. if doing that theres no point of water dropping from mold

Not necessarily true.
Your process doesn't make them as hard due to most powder coating are at around 375F - 400F for 10 - 20 minutes, and to get a real hard cast you need much higher temps for a 1 hour period. You can't powder coat at 450F - 480F for 60 minutes without degrading the powder coating.

You have to heat treat at high temps, then water cool plus cure for a 2 week period. Then powder coat and water cool. This way you take a boolit from 9 - 11 BHN up to 20 - 30 BHN plus put a nice hard powder coating on top of it.

There'a a heat temp and water cool temp chart on the link below.

http://www.lasc.us/heattreat.htm#chart

[Dusty Bannister]

Seems like the heat of powder coating would anneal the alloy back to original hardness. Is there another step in the process not mentioned?

[More_Slugs]

Seems like the heat of powder coating would anneal the alloy back to original hardness. Is there another step in the process not mentioned?

I'm confused by the anneal statement since it has to do with specifically cooling slowly to avoid stress cracking a metal, and not with heating it over a certain time. Unless I'm wrong?

Edit:
You would have to heat it at a much higher temp during heat treatment, close to the melting point, but PC'ing is over 300F lower than that point, so you can't/ won't soften the lead alloy.

[Dusty Bannister]

By much smarter members than me.

https://castboolits.gunloads.com/showthread.php?107059-Annealing-lead-bullets

[More_Slugs]

By much smarter members than me.

https://castboolits.gunloads.com/showthread.php?107059-Annealing-lead-bullets

Good information. Thank you!
I water cool my PC'd boolits, so no annealing.
If I didn't then it appears they will anneal.

Edit: I see where I left out water cooling after PC'ing and went back and added that. Apologies.

[Mr Peabody]

What do you find as an improvement shooting very hard rifle bullets?

[archeryrob]

I shot WW lead, water dropped from mold and powder coated and water dropped for 30-06 and 30-30 and all was fine. Now using 6.8 SPC in the AR I am getting a slight spread at 100 yards. I am hoping to get a harder and more accurate bullet. If not, I might change my alloy.

I cast and air cooled - Saved a bullet taped to a paper
Sized and Heat treated 1 hour at 460° and quenched - Saved a bullet taped to a paper
Next will be powder coat and quench, then size and gas check - Then save a bullet to the paper.

All will be filed and checked for hardness after a period of time. Then compared to water dropped, powder coated and water dropped and sized last. Then to know if it supplies any difference.

[Mr Peabody]

I haven't found hardness to be as important as design when it comes to group size. Maybe your ahead to try another bullet design. Which bullet are you using right now?

[MUSTANG]

For my variety of .30 cast boolits I cast, Powder Coat, and Heat treat I do the following:

1. Cast boolits and eject onto either a towel or a bucket of water dependent on the day/whim.

2. Place aluminum gas check on cast boolits; then press gas check on and size the boolits in appropriate Lee Sizing die, usually .310 inch ( may do .309 or .311 dependent on firearm destined for).

3. Powder Coat boolits using Shake and Bake method.

4. Stand Boolits in a silicone trivet to hold them upright.

5. Place in oven at 400 degrees; and cook them for 60 minutes.

6. Take the trivet of 400 degrees boolits (on a steel pan) and dump the entire trivet and boolits into 5 gallon bucket of cold water immediately from hot stove.

7. Run boolits through Lee Sizer die of correct size (usually .310 for most of my rifles)

8. Nose size boolits if needed (Dependent on the Boolit design and the Rifle to be used).

9. place into storage for 2-3 weeks or until needed.

10. Depending on alloy; I will get 14 to 21 BHN after 2-3 weeks using this methodolgy.

[fredj338]

Water dropping while casting then heating bullets up to 400deg for 15-20m undoes any gain. You are better off air cooling & water dropping out of the PC oven imo.

[More_Slugs]

What do you find as an improvement shooting very hard rifle bullets?

The higher the FPS, the harder the bullet requirement.

[More_Slugs]

Water dropping while casting then heating bullets up to 400deg for 15-20m undoes any gain. You are better off air cooling & water dropping out of the PC oven imo.

That would only be true IF you don't water cool after heat treating, whether it's after a 15-20 minute powder coat session, or for an hour to make a harder boolit.
If there's no water cooling after a heat treatment of any kind, for any duration, then annealing will happen.
If you water cool after a heat treatment, no annealing happens and you end up with a harder boolit.
It gets harder each day up to a 2 week period after letting them sit and "cure".
The higher the heat treatment, followed by water cooling, the harder the boolit.
The same boolits heat treated at 470F will be harder than the ones treated at 425F, after a 2 week cure.

[fredj338]

That would only be true IF you don't water cool after heat treating, whether it's after a 15-20 minute powder coat session, or for an hour to make a harder boolit.
If there's no water cooling after a heat treatment of any kind, for any duration, then annealing will happen.
If you water cool after a heat treatment, no annealing happens and you end up with a harder boolit.
It gets harder each day up to a 2 week period after letting them sit and "cure".
The higher the heat treatment, followed by water cooling, the harder the boolit.
The same boolits heat treated at 470F will be harder than the ones treated at 425F, after a 2 week cure.

I think that is what I said? Water dropping out of the molds then PC then out of the oven seems pointless.

[David2011]

Not necessarily true.
Your process doesn't make them as hard due to most powder coating are at around 375F - 400F for 10 - 20 minutes, and to get a real hard cast you need much higher temps for a 1 hour period. You can't powder coat at 450F - 480F for 60 minutes without degrading the powder coating.

You have to heat treat at high temps, then water cool plus cure for a 2 week period. Then powder coat and water cool. This way you take a boolit from 9 - 11 BHN up to 20 - 30 BHN plus put a nice hard powder coating on top of it.

There'a a heat temp and water cool temp chart on the link below.

http://www.lasc.us/heattreat.htm#chart

After casting a batch one time it was a few weeks before they were sized. No attempt to heat treat; I just got busy with other things. The boolits unfortunately age hardened very well. I was concerned that my Star lubsizer was going to break under the strain.