Asking for advice on Leading with home HiTek coated cast

[kevin c]

So I’ve been coating my own with HiTek for years now, but now for the first time I’m having really bad leading.

Same batch of powder. Same mix with acetone. Same Breville convection oven on the same settings. Same alloy, even the same style 9mm mold. I wasn’t seeing failures on the rub off or smash tests but upped the bake times anyway, confirming that I passed 180°C for three minutes using a K probe in a drilled out bullet set in the tray, which also confirmed the oven settings. But what worked perfectly before fails miserably now.

For a while I thought the problem was a poorly machined after market barrel, then different type rifling (lands and grooves versus Glock polygonal). Three other barrels, however, including a BarSto, KKM and a new OFM barrel off another Glock all gummed up quickly.

I finally remembered I have a good supply of commercial cast and HiTek coated bullets. I made up the same load and they ran perfectly to the tune of 350 rounds through two of the above barrels with zero leading.

So it’s not the barrels. It’s probably the coating, it’s prep, application or the curing. I haven’t heard of properly stored HiTek powder going bad, the prep and application is the same, so maybe the baking is going wrong? While the oven seems to work properly, with confirmed temps, and passes on the rub off and smash tests, an engineer friend suggested hot and cold spots in the oven causing uneven baking where some bullets would be fine but others would fail (I do rotate the tray halfway through the bake).

Ill check the oven, but does anyone have any other suggestions?

[Rapier]

I had a similar situation with moisture intrusion, so I went to a kitchen supply store and bought an air tight big mouth heavy plastic jar with a soft rubber gasket for storing the coating in. You can try that, to see is it helps.

[kevin c]

Rapier, I’m in the Bay Area, California, where humidity levels and temperature ranges are moderate. Still, I need to rule out issues I haven’t considered. How did your troublesome powder look?

[K43]

I had a different issue the first time I used Hi-Tek. It left a black coating in the bore that was near impossible to remove. Turned out I needed to clean my boolits with acetone or denatured alcohol before I coated them. Then they baked on nicely.

[kevin c]

K43, thanks for your comments.

My coating is clearly stripping off too, though what I’m scraping out of the barrels doesn’t seem to be coating cured onto the lands and grooves by firing, but metallic residues by the bright silver color.

I’ve considered silicone contamination of the casts (which Joe Ban has commented is death to good adhesion), but these slugs were cast, coated and baked far from where I use silicone sprays to lube my brass.

Maybe water contaminated acetone? But then I’d expect failures on the rub off and smash tests, unless it’s an intermittent thing like fully and underbaked bullets in the same batch, depending on tray position in the oven.

Any ideas welcome; I’ve got something like 20K bullets that need coating or recoating.

[gwpercle]

Check and see how old the powder is .
After a couple three years the powder starts to break down and fail .
See if the container has a date or a Best Used By Date on it ...
the powder may be going South !
Gary

[kevin c]

Thanks for your observations, gwpercle. You’re talking about HiTek, right? I thought the powder had a very long shelf life, but maybe not. All my HiTek powders are definitely a few years old, and it’s true they have gotten a bit cakey in the containers. I’ll consult with the US distributor and the Oracle himself (Joe Ban).

[Ausglock]

G'day... I have HITEK powder here that is 10 years old. still in the original container, that sits on the shelf in my shed. It is Gold 1035 and K15 Black.
I don't use it very often, mainly use Kryptonite Green, But a customer wanted Gold and Black bullets (his company colours) I coated baked 2 coats no issues.
The guy was happy as can be. fired them with perfect results. I have bullets coated 6 to 8 years ago and they still fire fine. was your bullets freshly coated or were they old bullets??

[kevin c]

Cast over the past year or so, Trevor, stored uncoated and done in batches. A big batch of 5-10 K will get a first coat, but may sit weeks to months before baking that and the second coat. The coating goes onto unwarmed bullets, though I do heat them on the oven top before they go in.

The powder is clumped but seems to dissolve up fine. My mix is diluted compared to standard to slow flash off and improve coverage (less powder per 100 ml of acetone but more applied per batch so the amount of powder per batch is the same).

Water contamination, either on the cold bullets or in the acetone, has been suggested by the US distributor, so I’m getting fresh acetone (and HiTek powder, just to be sure) and will prewarm the bullets before any coating goes on. An engineering friend suggested cold spots in the oven that, despite tray rotation, might have been missed by my K probed bullet set in with the rest and might leave just enough bullets underbaked to lead badly when the batch is loaded and shot but few enough to have been missed when I did the wipe and smash tests. So I’ll use multiple probes to look for cold spots.

Any other thoughts would be most welcome.

If it’s the oven I’ll need another to rebake 12K already done but suspect bullets. If it’s water related bad coating that’s 12K that’ll need to be recast. Then I have 16K+ more waiting in the wings. At least I have some commercially coated bullets to use in the meantime, but being a different bullet means a new load, press setup and rezeroing my guns. Ugh…

[1eyedjack]

How about bullet size? Had some 9mm PC coated that would lead the barrel because of over crimping which sized the bullet way under size which caused all kinds of problems...just something else to consider

[kevin c]

Thanks, 1eyedjack!

Both my own failing casts and the commercial casts that don’t lead are sized 0.357”, and I only remove the case mouth flare without crimping. I’ve never used a full length crimp die exactly out of concern about under sizing the bullet. AAMOF, I use only certain head-stamps of brass because they’re thinner and don’t ring or compress the bullet, or I just leave the Coke bottle look so long as chambering is fine.

[Ausglock]

I always have cold bullets when I coat. in cold weather, when the coated bullets get dumped on the tray, you can see the coating looks watered down. once dry, the coating looks normal.. they still bake and fire as normal.
You may have to do the acid wash before coating. once coated,(pre-bake) they can sit for months with no problems, then bake and fore normally.

[Soundguy]

any possibility your alloy has changed or drifted softer?

as a test..take some of your hitek coated and also lube them..alox or pan..or pressure lube..whatever..

now run them in a clean barrel..see if they still lead if yes..your hitek may be failing you..

[kevin c]

Don’t have a good sense of the weather out your way, Trevor, though maybe warm and dry? It can get cooler and damper out my way, and it was suggested to me that, like any lead stored without climate control, that the casts might have moisture, oxidation or even salts on them that I’ve trapped under the coating. So maybe a wash and heating over ambient temperature before the first application would help.

Soundguy I’m a bit confused, as somebody actually proposed Alox or traditional lubing as a save for my already HiTek coated bullets that are failing. E leaded barrel. Are you saying that the traditional lube over bad HiTek will also fail?

Oven testing tomorrow. New acetone and new HiTek on the way. I haven’t had wipe or smash test failures, just the leading, so testing requires loading and shooting coated and baked bullets, with failures meaning laborious cleaning of the leaded barrel. But it has to be done. Got a buddy waiting on me to coat his bullets as well as my own backlog.

[Soundguy]

Kevin, had a hard time getting on and posting..lots of board timeouts.. I see that auto correct changed a couple words in my post concerning the leading test. ive re edited it.
basically, take your hi tek that are failing and leading your barrel... lube over top of the hitek..then run them in a cleaned barrel... see if they still lead up. if they dont.. it points to, for whatever reason, your hitek failing. could be the batch..the application..something..
to a lesser extent..if the leading still occurs..it might point to a substantial change in your alloy or boolit property.. ie, drastically softer..or even..more shrinkage... softer alloys tend to shrink more than harder alloys.
so.. if your alloy was both softer and shrunk..you run into the issue of gas cutting at the base leading to a lube or coating failure due to the shrinkage..moreso that the coating.

if you have any plain base gas check you could pop a few on test bullets and see if they help.. they could also help troubleshoot a gas cutting issue at the base.

[kevin c]

Thanks for the clarification, Soundguy.

The finished rounds still mike out to .357” as expected; the hardness I’ll go check.

The alloy is in 240# batches and is supposed to be 95-3-2, the source metals all having been XRF’d. But while I think my math on making up the alloy is sound, there is the chance that I am in a “garbage in, garbage out” situation, since I found the source samples sent for analysis (molten metal droplets hardened as spatter on a metal plate) might have been contaminated by reusing the plate continuously without cleaning, so the alloy calculations could’ve used bad numbers. I didn’t think it’d be so far off as to really change the hardness, but I’ll check.

The Alox I’ll definitely try: it might help pin down the issue, and if the bullets don’t lead it’ll save me recasting several thousand.

ETA: I don’t have other lube options available, and I don’t have any gas checked designs.

[Petander]

Cast over the past year or so

Maybe the bullets have oxidized enough to prevent proper coating?

Cast some fresh bullets,coat,load and shoot to see.

I had my alloy analyzed and it has a Niobium contaminant, I wash my bullets in muriatic acid before Hi Tek coating. Otherwise my coating fails -even though it passes rub and smash tests.

[Soundguy]

Thanks for the clarification, Soundguy.

The finished rounds still mike out to .357” as expected; the hardness I’ll go check.

The alloy is in 240# batches and is supposed to be 95-3-2, the source metals all having been XRF’d. But while I think my math on making up the alloy is sound, there is the chance that I am in a “garbage in, garbage out” situation, since I found the source samples sent for analysis (molten metal droplets hardened as spatter on a metal plate) might have been contaminated by reusing the plate continuously without cleaning, so the alloy calculations could’ve used bad numbers. I didn’t think it’d be so far off as to really change the hardness, but I’ll check.

The Alox I’ll definitely try: it might help pin down the issue, and if the bullets don’t lead it’ll save me recasting several thousand.

ETA: I don’t have other lube options available, and I don’t have any gas checked designs.

Try the alox,.It will at least start you going down the path. your bullets don't need to be gas. Check design to use plane based gas checks. plane base checks are ultra thin flashing material, and they can be crimped over a regular bullet base.That's not designed for a gas check. i've bought mine from sages and they work fantastic, and they crimp. On while being sized very easily. they are great when you have a cast bullet that doesn't have a guess check shank, but you're running it at a little bit higher pressure than you would like you can just slap one of those on and usually it.Solves the problems of gas cutting completely,.

[kevin c]

Petander, thanks for your thoughts.

I’ve seen ingots go from shiny silver to dull grey, and also have found white and red oxides on some, but that happened slowly on bars stored for years. The bullets weren’t anywhere near as old, and still looked bright, iirc. Still, it’s another potential problem to consider.

Did you need any special analysis to pick up the niobium, or did XRF find it? How much is present? I ask because all my source metals get analyzed so I can (try to) make precise alloys, and it hasn’t been mentioned in the XRF summaries I’ve gotten, though I can certainly ask.

What concentration of muriatic acid did you use, and for how long?

The batch of alloy used for the problematic bullets is all cast and coated, maybe 12K unloaded and 3K loaded. That’s a good idea to coat, load and shoot some of the 16K that were a different batch of metal. Using the same supplies and process as before, no leading would definitely point to a bad alloy batch.

Soundguy, shooting moderate velocity 9x19 exclusively, I’ve never checked a bullet, so LLA seems like a good option for me to test out. Out of curiosity though, would checks work on the bevel based bullet I use?

[Soundguy]

you might be able to get a plain base check crimped on there.