Water quenching for hardness with PC/an observation

[xacex]

So, in trying to see if it is possible to get really hard alloy after powder coating I tried an experiment, and it seems to work. I took straight ww alloy that usually comes in at 9 bhn, tumble powder coated some cast boolits that were not water quenched, and baked them at 475f for 1 hour. After the bake they went into ice water right out of the oven. BHN after the quench...20.9! But, there was a problem. So you know that extra thickness powder coat adds? After letting these boolits sit overnight it was nearly impossible to size them. I had to use case sizing lube to get them to pass through. these things are so hard they bounce like marbles. My suggestion is size before powder coating in this instance, or you may have problems passing them through the sizer to put on gas checks.

Edit: I have been asked what method of application I used, and brand of powder coat, and if it was possible to share it here in the original post. The powder used is purchased from ebay, and is Black Death sold by DMC2. I find it produces a thick coat needed for this process. The application method I used for this test was the air soft bb method using black air soft bb's in a cool whip container, and shaken to apply. Boolits were then taken out by the nose, and set on non-stick aluminum foil on their bases for the bake.

[bangerjim]

Why do you need such hard boolits??????????????

[xacex]

Why do you need such hard boolits??????????????

I actually was not aiming for such hard boolits, and made the false assumption that the PC would hinder the water quench. These boolits will be shot in a rifle, and are gas checked also. Just a little experiment with PC, hardness from water quenching, and effectiveness on accuracy. Since I got these that hard I might as well see what the results will be. It will be interesting to see what will be left after a 1750fps trip from the barrel of the Beowulf. These are the mihec 502-383 grain with penta hollow points. I imagine the petals will break off, but with the boolits soft the projectile would peel off lead to the gas check. I intended to make these boolits about 15 BHN to see if I could keep everything below the petals to stay intact. Now I wonder if these will even break apart lol. The hardness is on par with my chamber pressures at 20.9 BHN.

[dougader]

You could pc, size and then heat treat if you actually need a bullet that hard...

[xacex]

You could pc, size and then heat treat if you actually need a bullet that hard...

Absolutely, but why bake twice?

[NavyVet1959]

Absolutely, but why bake twice?

I've wondered that about potatoes also...

[bangerjim]

Twice-baked taters........now I AM getting hungry!

[bangerjim]

You could pc, size and then heat treat if you actually need a bullet that hard...

I do NOT do this, but.......

I have read where those that must have hard boolits from water dropping rebake their PC'd slugs. You get a better "soak" at the temp you use for hardening than you do for the 10 minutes for curing PC. Some allude to an hour at 400-450? Then dump rapidly in cold water.

I see absolutely no need for hardening alloys that way. If I want a 15-20, I mix it for 15-20 air cooled. But I also have well over 750# of Sb rich alloy to play with.

PC backs off the need for the old school need for hard boolits as listed in all the old load charts. 10-12 subsonic and 14-15 sonic + PC does it ALL for me.

banger

[xacex]

I do NOT do this, but.......

I have read where those that must have hard boolits from water dropping rebake their PC'd slugs. You get a better "soak" at the temp you use for hardening than you do for the 10 minutes for curing PC. Some allude to an hour at 400-450? Then dump rapidly in cold water.

I see absolutely no need for hardening alloys that way. If I want a 15-20, I mix it for 15-20 air cooled. But I also have well over 750# of Sb rich alloy to play with.

PC backs off the need for the old school need for hard boolits as listed in all the old load charts. 10-12 subsonic and 14-15 sonic + PC does it ALL for me.

banger

This is why I decided to try this. I have done the twice bake thing, but if it can be done in one bake I save time, and energy. I agree that mixing alloy for hardness is an option, but for those who do not want to use expensive lino such as myself this is a viable option. So, with PC you can do a normal heat treat just like you would do for traditional lubed boolits, but because of the thickness of powder coat there are some considerations that come into play. If you do not need to play with hardening boolits because you are happy with paterns vs groups, or have a half a ton of alloy to blast away this may not be for you. I will continue to push the threshold of what is possible with this coating and see just how much it takes to bring rifle projectiles coated with polymer into the realm of commercial offerings as far as velocity and accuracy. Some times you have to look in the tool box, and combine the knowledge that has already been presented to come up with something that works better, or is more efficient.

[flyingrhino]

I don't understand why some people ask "WHY" you do something. That is the purpose of the forums....to share your experiences, good or bad. Thanks for this info. I too would like to crank up the hardness on my lead a bit. I was curious how the PC would handle the extended soak time. I'm going to try my own experiment based on what you just shared. THANKS!

[xacex]

Flyingrhino, There have been a few regulars on here that continually ask why, and regurgitate the same stuff over and over. If it does not pertain to you maybe they should stay out of the conversation. Since the PC stuff is relatively new, and I have only been doing this PC thing for a couple of years or more I am looking at the combined knowledge of traditional cast boolits, and how it pertains to PC boolits. I tried what people above you mentioned,but no one that I know of has gone beyond that. That is why I had to try it for myself. Now I can heat treat for hardness as I am coating, and can blend alloys accordingly. I just did not know if the coating would withstand an hour long soak, but it has passed with flying colors. I was casting and heat treating like this before PC came around, but had an additional step of gas checking, and lubing.Now the lubing is done, but still need the sizing, and gas checks so there is no time saving in that regard. This has a great potential for those who like to store boolits heat treated, and once those boolits soften to a degree they can be re-heat treated back to that hardness without the problem of lube degrading over time, or not having boolits ready to load because you stored them without lube. Let us know what your results were when you get around to trying it.

[popper]

I've been H.T.ing ESPC'd for couple years now, 400F for an hour, into cold water. Need to try the 475F and see if coating AND boolit hold up, getting close to slump temp of my alloys. I shoot a 170Gr GC in 308W ~2700 fps, 1/1/2" @ 100 so far. Straight WW can't do that. Thinking of a jig to dip noses in boiling water to AC the nose for hunting. Check the Cu added alloy thread for results with really hard boolits, like 35+ BHN.

[pretzelxx]

And here I thought my boolits were hard. Holy cow!

I water quench right out of the mold to be able to handle them instantly. Theres something about not wanting dents in them when I drop them 2 feet onto concrete.. Then I powder coat to soften them back up! Size after coat

[popper]

Squished in a vice with Superhard bar, same size dent in both. Started with 3-4% Sb with 2% Cu, H.T.d 415F for an hour. BTW, Bumpo's calculator shows Superhard @ 15 BHN and Foundry @ 30 BHN which is only 20% vs 30% in S.H. Roto gives no BHN for S.H. but equation says ~36 BHN. Anyway, my experience shows you need a good thick coat of PC for H.T., coating seems to shrink when H.T.d Edit: - normal for thermoplastics and extra thickness appears to be needed for HV/high pressure. Some of the PC does get scrubbed off. L.G. lubed PC tests indicate, by higher fps, less friction.

[kbstenberg]

Question please. Does the PC affect the BHN readings?

[xacex]

Question please. Does the PC affect the BHN readings?

Yes, PC does have its own hardness, and would affect the BHN reading. I sanded the PC off in the test section to use the harness meter.

[kbstenberg]

Thank you!

[Stilly]

You could pc, size and then heat treat if you actually need a bullet that hard...

Have you done this? I was under the impression that since PC cures at @400 deg that baking the pills for 1 hour at 475 might be dangerous to the poor little guys. I just envision pompei and lava running down places...

That is good if it can be done.

Actually I think I might have had a touch of lube still left on the pills before they went into the oven, which produced the bubbled burn mark in a spot or two...

[xacex]

So I went out and shot these with the same load I was using before, and low and behold through all of the groups the accuracy increased just as it would if these were traditionally lubed.

[Whizzer]

I dislike having to use a gas check. I have 30 Winchester molds FOR checks, but I don't like to use them. If the Heat Treating could avoid checks with Clip On Wheel Weights I'd write in your names for President next November. With Powdercoating, I've been a skoshe over 2000 FPS in 30/30 and a little under for 7.62x39 without leading and no checks, but I'd like to go FULL HONK without them.

My handgun loads don't lead with air cooled Wheel Weights and PC, even 9x19. I can push a 105 grainer through my tiny Kahr PM9 barrel screaming over 1400 and it won't lead the bore. Shoots about a foot low, it's outa there so fast!

Surely 20+ Brinell would facilitate 2400+fps in 30 Win without those darned checks. (Mine just don't fit. And I don't have any dies for homemade. That, and just on principle...I don't like using them. If I was shooting an elephant gun, then maybe...)