BHuij
Active Member
I'm trying to get the strongest COWW alloy bullets I can come up with. I understand that heat treating at close to slump temperatures and then water quenching can get COWW up to the 30 BHN range.
Trouble is, I'm powder coating in place of lube. 400 F for 20 minutes more or less undoes all the HT/Q benefits.
I've read several topics here and elsewhere, and some people were doing tests to find a way around this problem, but I never saw definitive results. So I figured I'd ask before I go through the trouble of doing the tests... although I may just do the tests anyway, because who knows if my COWW is the same as anyone else's. What I want to try:
1) Cast some bullets. The ones I'm using where hardness particularly concerns me are my .223 55 grain Lee ones, as they're intended for my AR, and I'm trying to push the envelope on velocity without losing accuracy. Water quench some from the mold and air drop others. Measure hardness immediately, and at 7 and 14 days.
2) Shake & bake the bullets at 450 F for 60 minutes, water quench immediately out of the oven in ice cold water. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can still pass a smash test, or if the coating is ruined by the over-baking.
3) Shake & bake the bullets at 400 F for 20 minutes per my normal PC procedure. Allow to cool completely, then attempt a heat treat/quench at 450F for 60 minutes after the PC already cured and cooled. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can still pass a smash test, or if the coating is ruined by the second baking.
4) HT/Q some bare lead bullets. Shake & bake at a temperature too low to anneal significantly (recommendations here? Thinking maybe 250 F), and see if I can get a good cure on the PC. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can pass a smash test.
Ideally I'll be able to come up with a .223 bullet from my COWW alloy that remains at or near 30 BHN and has a satisfactory powder coat.
Trouble is, I'm powder coating in place of lube. 400 F for 20 minutes more or less undoes all the HT/Q benefits.
I've read several topics here and elsewhere, and some people were doing tests to find a way around this problem, but I never saw definitive results. So I figured I'd ask before I go through the trouble of doing the tests... although I may just do the tests anyway, because who knows if my COWW is the same as anyone else's. What I want to try:
1) Cast some bullets. The ones I'm using where hardness particularly concerns me are my .223 55 grain Lee ones, as they're intended for my AR, and I'm trying to push the envelope on velocity without losing accuracy. Water quench some from the mold and air drop others. Measure hardness immediately, and at 7 and 14 days.
2) Shake & bake the bullets at 450 F for 60 minutes, water quench immediately out of the oven in ice cold water. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can still pass a smash test, or if the coating is ruined by the over-baking.
3) Shake & bake the bullets at 400 F for 20 minutes per my normal PC procedure. Allow to cool completely, then attempt a heat treat/quench at 450F for 60 minutes after the PC already cured and cooled. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can still pass a smash test, or if the coating is ruined by the second baking.
4) HT/Q some bare lead bullets. Shake & bake at a temperature too low to anneal significantly (recommendations here? Thinking maybe 250 F), and see if I can get a good cure on the PC. Measure hardness right away and at 7 and 14 days. See if PC'd bullets can pass a smash test.
Ideally I'll be able to come up with a .223 bullet from my COWW alloy that remains at or near 30 BHN and has a satisfactory powder coat.