Heat Treating while Powder Coating

[YogiSC]

MP Molds 62gr NATO for 223. COWW / Range Scrap mix (3 Sb, .5 Sn per NITON, As not measured). Eastwood Ford Blue powder, 3 thermocouples inserted in drilled out version of same bullet in small non-conv. toaster oven.. 20-30 minutes at 460 PID setting (all tc's within 450-470).. PC coats fine, bullets harden within 24 hours approaching linotype levels (I use a "vise squeeze" and Shore D durometer method to measure hardness). Biggest issue is using only back half of oven due to hot/cold spots inherent in little radiant heat ovens like this)..

[Conditor22]

TATV did a test

[GregLaROCHE]

That’s an interesting chart. The first time I’ve seen it. The results surprised me.

[tomme boy]

You need to heat them for an hour to make the biggest difference.

[Rcmaveric]

From what I gather and read. Heat treat first to get your hardness gain. Water dropping from mold is also affective but it causes inconsistent hardness due to mold temp fluctuations.

Then PC. If you water drop after pc the BHN lost is negligible. But if you air cool after PC you loose a lot of hardness to annealing.

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[YogiSC]

Sorry forgot to mention I WD directly following PC at 460F. Time is actually less important..Dennis Marshall's article in Cast Bullets as well a paper I have from 1935 show time is less important than temp. Just reducing a step is nice

[bmortell]

ya for PC COWW or 50-50 i always just do 20 min from after pc starts melting and turn it up to 425 for the last 5 min then chuck the tray out the oven into a cold 5 gallon water bucket fast as i can. ive never bought a hardness tester cause targets or expansion test tell me what i need but PC quenching works for me. but i let them age a few days after to get harder before loading. i might start heat treating before pc also to see if it gets lets corner dents from the PC shaking process though

[YogiSC]

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[OS OK]

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[GregLaROCHE]

When dumping boolits into cold water while still hot, don’t you risk having them hit each other before they reach the water, causing deformities?

[popper]

No, just dump them. I did make a handle rig so I can set the whole tray into ICE water so no dumping. I see no difference. Time AND temp. make a difference. When the Sb/Sn alloy cools it forms Sn rich/Sb rich layers. When ACd these layers morf into blobs that are soft. WD freezes the layers around the solidus temp. When heat treating just below slump temp it takes TIME for the molecules to reform the layers (it is a solid and molecules have to move), then WD freezes them. Faster you 'freeze', harder bullets. PC does slow it (slight insulator) just a tad but I can't tell the difference. One hour min works for me but I've left them longer - no rush.

[bmortell]

When dumping boolits into cold water while still hot, don’t you risk having them hit each other before they reach the water, causing deformities?

if you well wrap the tray with heavy foil so there isnt slack the boolits all stick in place even throwing it in fast, exception of 220 gr 30 cal with a shank they have huge leverage standing and some pull off, to me the few minutes peeling them off is worth the peace of mind cause i do get dents if i normal water drop from mold

[hickfu]

I played around with Heat treating at different temps for different times and the best I came up with was 460* at 30 minutes gave me better results then 400 at 1 hour or even 2 hours. If I really want then hard I do it at 460* for an hour and they are just north of 30bhn

[popper]

Use Yoshi copper cooking sheet and they don't stick or tear like al foil.

[Petander]

I coat normally first,then harden as a separate bake.

[gnappi]

I coat normally first,then harden as a separate bake.

That's an interesting chart, thanks.

So you cast (no quench) coat and let air cool, then harden as in the above chart?

[Petander]

That's an interesting chart, thanks.

So you cast (no quench) coat and let air cool, then harden as in the above chart?

Yes. But I don't really heat treat harden many bullets at all.

But I have experimented with heat treating and to me it seems a good idea to coat normally first. Then I know for sure my coating was good before heat treating.

Here is the link: http://www.lasc.us/HeatTreat.htm

[white eagle]

so by the chart above powder coating does ad a bit of hardness to a boolit

make me think lead/tin alloys are getting harder and might be able to handle
more pressure and velocity

[fredj338]

TATV did a test

For me, air cooled, quench out of the PC oven after 15m @ 400, gives me a 3-4bhn bump. I file off the PC nose & test a few days after casting.

[Petander]

I think I undercured a batch of 44's so right now they go into an oven for an hour 430°F. Then 50°F splash and after a few days they are good for hot loads.