Home Forums Reloading Bullet Casting Powder coating - couple of finesse questions

Just took my first experimental batch of bullets out of the oven, they're cooling right now. Only used a small handful - 23 bullets - in case I totally screwed them up, but will size and load them today and try them at the range tomorrow.

In the meantime, some questions on refining the tools/techniques. When I got the oven I got a pan to go with it but it's fairly thick and made of steel since it attracts a magnet. Got the oven to 400 exactly as shown by the oven thermometer inside but when I put this heavy tray in the internal temp went down to about 360 quickly, maybe 2-3 minutes. I turned the temp dial up and it still took some 6-7 minutes to get back to 400, that's when I started the 10 minute timer. Once back at 400 the oven stayed there very steadily.

So, I'm thinking a lighter aluminum pan would be better since it won't have as much mass to soak up the existing heat and the oven should return to correct temp more quickly, correct? Have you guys used those throw away aluminum foil type baking pans? Seems they'd be a bit flimsy to hold the weight of 200 bullets but if supported underneath they wouldn't act as much of a heat sink at all. Btw, I'm using non-stick aluminum foil on the current pan and would use that no matter what.

Also, I was reading about PMT - part metal temperature - since the powder instructions say 400 F/10 min at PMT, this is the RAL 6018 powder Yondering recommended in his post. Don't know of a way to actually measure the bullet temp, but as the oven was reheating and going back up through 375-380-390 etc. I could see the powder melting to a shiny appearance. I'm guessing once the oven thermometer says 400 again that you might as well start the timer.

On the steel tray. Conversely, since it is a large heat sink along with the bullets, perhaps using it would work better since it heats up more slowly and might be a better indicator of the bullets' temp or allow them time to come up to proper temp where a light aluminum pan might allow oven internal temp to hit 400 while the bullets themselves, the substrate in PC terms, would still be below 400?

Any thoughts on the matter would be welcome.


Yeah, I know I'm over thinking this but that's a computer programmer's mind at work...

I use light weight aluminum pans, covered with the non-stick aluminum foil. Never had an issue with those pans.

I have not tried a heavier steel pan, don't know if it'll cause problems, but I seriously doubt it'll do anything better than an aluminum pan except take longer to heat up and cool off.

On the timer - yes you want 10 minutes once the bullets are up to 400*. To achieve that, I just set my timer to 20 minutes and start it when I put the bullets in. I know the oven setting needed to achieve 400, so I set it there at the start and leave it alone.


One further comment on bullet quantity for coating - I realize you were just trying out a handful of bullets at first. However, I've found it's harder to get powder to stick to just a few bullets, compared to a larger batch of several hundred. I typically do 300-400 9mm bullets per batch, which fills a 32oz yogurt container 1/2-2/3 full. I coated 750 of them the other night; split into two batches worked out perfectly. I do go with a fairly light coat so the cake of bullets breaks apart easier (I just dump them all in the pan, no individual handling needed), and try to use the right amount of powder so none is left in the container after shaking them.

I use cookie sheets or cake pans covered with non-stick Reynolds wrap. I have found Tupperware square containers best for coating bullets, I use rubber gloves to handle bullets the powder doesn't stick to the gloves. I preheat my oven for 10 minutes for the first batch. Are you using heavy weight air soft bb's in the bottom of your container? This helps with static charge and the powder sticks to the bullets easier.

Did a bigger batch yesterday, some 231 bullets which was basically half a yogurt tub full. Used an aluminum pan but I'm not seeing that it makes a big difference. I forgot to time it each day but my rememberance is that it took about the same time to get back up to temp whether using the heavier gauge steel or lightweight aluminum pan.

In fact, yesterday I let the oven get up to 425 in anticipation of heat loss but it still went down to a low of 340 despite the aluminum pan this time and still took a good 10 minutes to get back up to 400. Could be the additional mass of the bullets this time but it seems to me that the biggest heat loss is opening the door to put the pan of bullets inside even if done as fast as practical. Anyway, I just crank up the thermostat until it gets and stays at 400 then set the 10 minute timer. The bullets come out well coated and shooting trials yesterday morning showed no leading whatsoever.

Also, still getting a feel for how much powder to use but I'm eyeballing it pretty close. Used a half a plastic spoonful and shook the container hard for a count of 20 which coated all of the bullets well with only a tiny amount of powder left in the bottom of the plastic tub. Not a problem generating static electricity in Idaho on a clear and chilly March day, in fact I get zapped all the time touching anything that grounds me.

Sounds like you've got that down pretty well, that's exactly how I do it too.




The only reason you're needing to use airsoft BBs is because you decided to use a different container than I recommended. I've said to use yogurt or sour cream containers specifically because they generate the static needed. The material should be white plastic with the #5 recycle mark on the bottom. Tupperware and other containers are different and do not work as well.

Using airsoft BBs causes more work for yourself without any better results, compared to just using the right container to start with. Look back at the pictures I posted at the beginning of my powder coating thread, they clearly show good coating without using airsoft bbs.

I'm surprised you don't have Campfire basement physicists challenging your claim that yogurt or sour cream containers work better, but you are correct about that. I tried to get Tupperware to work, but to no avail.

It seems to have something to do with the type of material and static generation. That's outside my field of expertise to explain why, but the results are pretty clear. (No pun intended, but the clear containers don't work as well.)

Using a round container works much better & the air soft pellets are just adding a step you don't need. It only takes a few seconds to get a good coating & you're ready to bake. Oh, & the Rock Chucks are starting to pop out!

Dick

Man, I sure wish we had rock chucks here in the PNW. (OK, not really for the damage they cause, but for varmint hunting...) I see a lot of them in central Oregon where my in-laws live, but most of that area seems to be pretty closed off to public shooting these days unless you know someone with property.

just put a few ingots in the bottom of the oven to use as heat bricks and you wont have the temp drop.

kind of what i do, i just slide my ingot mold in on the bottom. that way there is no muss or fuss. the 4 lbs keeps everything even

I probably shouldn't say anything, no experience at all on this topic.
Came here because I'm curious


But, considering the thermal mass of a batch of lead bullets,
Your steel pan would be fairly insignificant.

Unless its dam heavy.

None of that stuff matters at all. Just let the bullets in the oven get up to temp (400° F) and hold for at least ten minutes. Leave them in longer if you're not sure; as long as the oven isn't too hot it doesn't matter.

Grill type lava rocks lining the bottom helps too. Also always pre heat oven and basket.

I use baskets from bed bath and beyond. I use one to dump
Into and sift off excess an then a second to sift off more and to bake into. No worry of standing, but I only bake in a single even layer. Using two like this keeps them cleaner and in use longer. Before I used two, I would have to replace the baskets because the repeated pc coatings closed up the screen. Now using two, my sifter basket never gets cooked and can be whiped or washed clean. And my cooking basket, because its been sifted once before contact sees far less residue.

I also like to pre heat my bullets in baskets on top of the over as the oven pre heats. You dont want too hot here. Summer sun can work too, but can actually get them too hot. I like them warm to the touch.

For coating I have changed to large containers. Mine are Nesle Quick jugs from neighbors with a bunch of kids. The jugs are nearly a gallon in cap. I roll and tumble the bullets NO BB’s needed for me. The bullets usually coat quick and even.
Good luck,

CW

If you have to sift powder off though, you're adding way too much. Just add enough powder so the bullets are coated with a thin layer after a brief round of shaking, then bake them. No sifting or preheating needed, and you don't need to worry about temperature dropping in the oven because you're going to let them sit in there for at least 10 minutes after the bullets reach 400° F. The oven temp before that does not matter.


Guys, adding more steps to this process does not improve things. Don't fall into the trap of thinking more work or extra steps gives a better result; it doesn't.

I do t know what kind of magic powder you use but the amount that sticks depends upon static not the amount you have in the shaker...

Shaking off DETERMINES a nice thin coating thats preferred.

Its not extra its required. If you done see the need more power to ya!!

Pre heating the over MAKES even heat. Again in your magic oven things must just work better with that magic powder.

CW

Again, extra steps does not mean better results. If you can't get good results as I described above and in the powder coating tutorials I've posted on various forums over the years, you could ask yourself why, what's different, etc.

BTW static is generated by shaking the bullets in the tub. If you have trouble getting powder to stick well without adding too much, shake harder/faster to generate more static. 10-20 seconds is enough time, but it should be hard and vigorous, no gentle one-handed swirling as I've seen some guys suggest.

Before I discovered the yogurt and sour cream containers I would rub the cool whip container over my 1970s shag carpet for 20 minutes and then rub my cat 5 times. Worked like a charm to get static but it sure was hard to get the cat to sit still.

Thanks, Dinny

Hahaha! I bet the cat liked that almost as much as holding him under the toilet lid for a bath.

I shake mine, then pour out the bullets and excess powder on an oven sized tray I made from 1/4" hardware cloth mesh. Foil underneath captures the excess powder, which goes back in the container. The wire tray goes in the oven, with the oven's catch pan below it to capture any drips. I don't worry about orientation before baking and don't handle the bullets individually. I bake in large batches and for more time than indicated to make sure they cure properly (usually 15min IIRC). I pull the tray out to cool, shake it to loosen the bullets, then pop them apart and run them through the sizer once cooled. They're ugly, but functional for my plinking purposes.