Strange problem encountered with PD'd bullets

[Stilly]

Welp. Folks I have been using Tiger Drylac coatings blue, flourescent green and Pacific Coatings Glow in the Dark. I have not had any issues yet but I will take another look. All of my coatings are glossy. I will see if I can get a msds on the glow in the dark (got it from a seller on fleabay...)... :\ In the meantime I say to have a closer look at that barrel and send it in to get replaced if possible. Then start over and watch the new one closely...

For what it is worth, I have also added a little hBN to my coatings, just to see if it made any difference. Uhhh, don;t ask about it just yet though cause I just started last week and have yet to shoot any... :\

[Linstrum]

No mystery to me what is happening. The pigments and fillers used in coatings are quite often minerals like white titanium dioxide (already mentioned), artificial ultramarine blue lapis lazuli, red ochre, yellow ochre, and black magnetite. All those have corundum and silica (flint is a form of silica) contamination. Red ochre pigment is a commercial abrasive for steel and gems that contains hematite iron oxide. Black magnetite double iron oxide is easily identified with a strong magnet, and is also a commercial abrasive and polish used for gems and metals that is 1.5 to 2 points harder than many steels on Moh's Scale of Hardness used for minerals. Hardened and tempered steel = about 5.5 and red ochre and magnetite both = 7, a little harder than titanium white and about the same as flint or garnet sandpaper! I'd skip the colored PC and go with a clear polymer PC with molybdenum dioxide dry lubricant powder that YOU add for black color. I personally just use Alox for my cast wheel weight .38 Special, .357 Mag, 9mm Parabellum, and .45 APC ammo. Been using Alox since 1979 and I have no complaints. But whatever you choose, good luck on finding a replacement that is not also used for a commercial sandpaper abrasive to coat your boolits.

rl 1,174

[ebner glocken]

magnetite- Very bad in boiler under high velocity, high pressure, and squeezed through valves. Erodes things quite quickly. Nothing you want in your barrel.

Ebner

[IllinoisCoyoteHunter]

Maybe someone needs to run a group buy on clear powder coat from this place...

http://www.prismaticpowders.com/colors/PPS-4005/

[Beagle333]

COMPOSITION/INFORMATION ON INGREDIENTS
Ingredients:
*This product contains no reportable materials at or above normal reporting levels.

The clear can't be harmful.... it doesn't contain anything!

[Beetmagnet]

Maybe this is silly but I'll mention it. If the black matte abrasive finish is the problem, then maybe adding some of the other glossy colors to the black would help. I say this because I PC a few 45's the other day with the black. There was some white left in the gun, and they mixed together. The bullets came out all black, but glossy like the white and red HF powders. Perhaps we can still use the black HF powder (if it is a problem, and I'm not convinced it is) if we just mix in some white or red.

[dverna]

If (and this is still a question) there is erosion, it will kill PC'ing for things like AR's and target guns. It will not have much impact on hunting guns unless someone does a lot of plinking/target shooting with them. But for velocities under 1600 or so, PC'ing is not really needed anyway.

I had come to the conclusion that I would continue to use traditional lube for pistol bullets anyway as it works fine and are easier to use - at least for me. Hy-Tek is a great option for pistol bullets if you do not want to invest in a Star - and Hy-Tek works very well in pistols. PC'ing seemed the best option for high velocity rifle bullets until this issue was raised.

Still too early to know if erosion is an issue or not. So this will be a watched thread for sure.

Don Verna

[Maximumbob54]

So this whole box of the same bullets coated with the same powder sized in the same Lee .357 die that start to finish are all still .357 in diameter but this stuff is supposed to be abrasive??? What am I not getting? I've not shot many of them yet but shouldn't the die be .358 by now? Is it only under pressure in the bore that these are a problem?

[dverna]

MB54.
I would suspect velocity is a more significant issue to erosion than pressure.

There is also the matter of number of cycles. Shooting a slightly abrasive coating may not have much affect in 500 rounds but what about 5,000 or 20,000 rounds?

Don Verna

[popper]

Maybe we could get Gear to use his lube wear tester on some powder to get a real answer, instead of guessing. Gear?
I cleaned the 40 Monday after ~ 400 rnds. There was a good visible deposit neat the chamber but it came out with a brush very easily. Not lead.

[Linstrum]

Maximumbob54 and others, wear due to motion is a CUBE of the velocity function. That is, Wear = Velocity^3. What that means is if you double the velocity then the wear is eight times. 2 cubed is 2 * 2 * 2 = 8. Therefore, if the velocity of the bullet going through your sizer is 1/10 feet per second and the velocity through your barrel is 1,400 feet per second at the muzzle, then the wear through your sizer is going to be unmeasurable what it is at the gun muzzle. Mathematically, 1,400 feet per second ÷ 1/10 feet per second = 14,000 times faster, which means the gun muzzle velocity is 14,000 times the velocity through the sizer die. But the wear factor itself is actually 14,000^3 = 14,000 * 14,000 * 14,000 or 2,744,000,000,000 or an incredible number of times greater wear factor. However, if your wear at 1/10 feet per second is extremely close to zero in the sizing die, then 2,744,000,000,000 multiplied times Almost Zero is a very, very tiny number, so even though the DIFFERENCE BETWEEN THE VELOCITIES through your sizer and your gun barrel have a wear factor difference of 2.744 TRILLION times, the actual wear that takes place is still very small. Because of the huge wear factor values involved in high velocities, GOOD PROJECTILE LUBRICATION TO KEEP WEAR FACTORS CLOSE TO ZERO IS A MUST! Race car drivers know all about how fast their tires wear out at 200 mph compared to 50 mph, 200 ÷ 50 = 4, 4^3 = 64, so they get about one sixty-fourth the miles on their tires at 200 mph than at 50 mph IF the temperature of the tires is the same as at 50 mph, which it isn't. When the temperature goes up, then the additional wear DOUBLES for every 10 degrees Celsius (18 degrees F) increase in temperature!

rl 1,203

[IllinoisCoyoteHunter]

Very interesting.

[Love Life]

My brain hurts.

[Moonman]

Too much LOCO WEED out that way.

[IllinoisCoyoteHunter]

I have nothing against PC, as I have never done it, and we have no definitive evidence of its abrasiveness. BUT, I think I will stick with my Star and conventional lube.

[gds]

I'm just not sure that the powder coating is the culprit. I mean lets be honest. Shooters and especially us casters tend to be cheap. I would venture to say that the harbor freight flat black is probably the most used powder for our purposes. i would think that by now we would have had many more reports like the OPs. Some guys are pushing a lot higher pressures in there guns and shooting a lot higher volume then even the OP. I am watching my guns and so far I have not seen any appreciable wear. granted my high round count powder coated shooter is an AAC model 7 300 blk, with 99% subsonics thru it.

[MacFan]

The barrel slugged at .356 and the plated bullets mic'd at .355. "Several thousand" plated were shot without checking the barrel if I read your post correctly. I'm thinking (guessing) that the plated bullets were the original cause of the problem. The erosion from hot gasses and debris simply continued with the powder coated bullets. Kind of like plasma cutting or a water jet, once you get a hole or path started metal disappears real fast.
All just speculation on my part, I hope you get the problem figured out.

Afterthought- Are we assuming that all the dirt and garbage left behind in a barrel when shooting conventional lubes and jacketed isn't abrasive at all?

[sparky45]

I have nothing against PC, as I have never done it, and we have no definitive evidence of its abrasiveness. BUT, I think I will stick with my Star and conventional lube.

I still use my Star with every boolit I cast, only I use it exclusively as a sizer.

[Beagle333]

This seems to be an isolated case. Time will tell, but I agree with "gds" above, there are a lot of us shooting powder and only one report of wear.

[Mbedwell1971]

I agree. I started PCing with gloss red HF but have decided to do some matte black. I am going to do some comparisons with the two. I am curious if the velocities will be different. I will chronograph some tomorrow.