Strange problem encountered with PD'd bullets

[popper]

Borderguy - most throat erosion is due to hot gas & burning powder particles at high velocity. 303guy had some pics of boolit bases dented by burning 4895. The Dupont site has a lot of plastic/TiO2 data if someone has a company address that can register and make data available to us? Last time I read the TiO2 content in white paint, it was < 10%. Oh, mohr hardness of annealed copper is 7, most TiO2 is 6. It is also used in suntan lotion, makeup. Probably less hard than fish scales used in makeup. Yes, if you shoot a $2K barrel you might be concerned. But so would guilding metal used in jackets.
It's NOT abrasive enough (HF PC) to remove even minor leading in the barrel. Visible lead in my 40 wasn't removed after 200 rnds PCd. IMHO, until proved otherwise - not a problem.
The yellow has lead chromate coloring in it, a yellow pigment called 'middle chrome'. Navy used it for years as an aluminum corrosion protection. It is slightly toxic. Kind of like red lead. Both red & yellow chrome have mohr hardness of 3. Not a problem.

[Boarderguy83]

Popper and Doc, thank you both for that, I was completely unaware. I do appreciate learning new things.

John

[popper]

are sure that what you are calling erosion is not just the taper at the start of the rifling?

[Boarderguy83]

Absolutely not. I know the pictures dont really show the erosion very well, but I promise you that there is a solid .5 inch of "freebore" before the bullet would actually start to engage the rifling. I can actually look just forward of the chamber and see where the rifling used to be. When comparing my bore to other Glock 19 bores, this one is definitely been eroded in some fashion. I wish I could get some better pictures to post on here.

John

[Cane_man]

maybe this particular barrel slipped thru QC... substandard machining, poor heat treating, defective bar stock ???

[Doc Highwall]

Having worked with abrasives both polishing and lapping compounds some compounds break down faster then others, which could explain why the first .5" shows the wear in the barrel also the lead in the sizing die not being subjected to higher pressures might not show any wear at all.

[MUSTANG]

Well looks like I had a fat finger when I placed my order. I opened the Harbor Freight box containing the Powder Coat this afternoon, I thought I had ordered 1 each Red/White/Yellow/Black; but I had three - yes three 1 pound cans of black Harbor Freight Powder Coat. It would be the one that is MOST SUSPECT for abrasion concerns.

Well, I guess that I'll wait and see what the posts say to refute or confirm the Black Harbor Freight PC is abrasive. If it turns out reports confirm it is abrasive, well my fall back plan revolves around a Brazilian Contract S&W 1937 .45acp/.45 auto rim; a re-run of the Smith & Wesson US Model 1917. I bought this revolver back in the late 1980's, and it shot terribly with jacketed hardball, the barrel literally looks like a sewer pipe on the inside, but pretty fair on the outside. Lee and RCBS 230 grain round nose cast boolits shoot fair. What is strange, is that a 250 grain .45 wadcutter shoots the X ring out with ten rounds at 25 yards when I do my part, but flattens primers.

Long way around, I may consider making lemonaide by using the Harbor Freight Black PC with .45 Round Nose Cast Boolits to smooth out the sewer pipe if it should prove to be mildly abrasive.



I sent Harbor Freight an e-mail request this afternoon for the MSDS on all 4 of their Powder Coat paints. I'll try to post the MSDS's here when I get them.

[Magana559]

subscribed!

[NWPilgrim]

IIRC, hot gasses bypassing the bullet will have a serious effect on the throat. They travel MUCH faster than they will propel a boolit. Look at the flame cutting that occurs with some revolvers. And there is the idea that the forcing cone splitting on the Smith 19's shooting light bullets is partially attributed to the severe impact of gas bypass.

Plus, the gas is hottest, most compressed near the chamber. As gases expand they cool. So the further the gas expands down the barrel the cooler it gets.

[Boarderguy83]

Thank you for all the replies, I am glad to see so much interest in this particular subject. I am really hoping that some how by a strange turn of events, I received a bad barrel, and that the black HF PC is not actually the problem. NWPilgrim, thank you for the information, I was absolutely ignorant about that.

John

[Cane_man]

haven't shooters in Europe been PC'ing for quite sometime now... has anyone heard about problems like this from over the pond?

[Thundermaker]

I've been trying to find another instance of this. Nothing is turning up. Powder coating seems to be very popular among .300aac shooters. They aren't reporting any problems. Everybody is using the harbor freight stuff, but not the matte finish stuff.

[TES]

My test results for HF Black were horrid. See HFPC "Piglet method" for my results. I stopped after all the crud in my barrel.

[Thundermaker]

Maybe it has something to do with whatever they use for pigment. Black car paint doesn't hold up as well as other colors either.

[Boarderguy83]

Well I honestly hope its just the matte black stuff that is the problem. Im going to go to HF today and buy some of the red, and see how that works out, as it seems many folks have had great results with that, and no reports of erosion.

John

[IllinoisCoyoteHunter]

Could you try to post some more pictures? Maybe try to get the lighting just right so we can see the erosion? Thanks a bunch!

Tony

[badbill2]

I have not had any excessive wear with the PC boolits, however, I did mention awhile back that the HB "Black Color" must have different compounds from the other colors. This is evident when cooking and getting a gummier coating that appears thicker and more resilient??

[hubcap52]

Seems to me that the speed a boolit goes down a barrel would have 0 to with how much it eroded any metal. While it might erode it faster, it wouldn't erode it more. I think someone also mentioned to check the wear on the sizing die. Should be equal to any bore wear. One could also PC an ingot (or any other piece of metal for that matter) and rub it on a piece of same or similar metal and check the results.

[IllinoisCoyoteHunter]

A bullet going down the barrel engages the rifles and it swaged down a bit more than when it goes through a sizing die. Plus, as it engages the rifling it begins to spins but wants to keep going straight. There is an immense amount of stress on both the bullet and the rifling which creates much more pressure than just being pushed through a sizing die. Ever fire a big bore handgun and the gun spins off in one direction during recoil? That is literally the bullet spinning the gun in your hands.

[MUSTANG]

Well looks like I had a fat finger when I placed my order. I opened the Harbor Freight box containing the Powder Coat this afternoon, I thought I had ordered 1 each Red/White/Yellow/Black; but I had three - yes three 1 pound cans of black Harbor Freight Powder Coat. It would be the one that is MOST SUSPECT for abrasion concerns.

Well, I guess that I'll wait and see what the posts say to refute or confirm the Black Harbor Freight PC is abrasive. If it turns out reports confirm it is abrasive, well my fall back plan revolves around a Brazilian Contract S&W 1937 .45acp/.45 auto rim; a re-run of the Smith & Wesson US Model 1917. I bought this revolver back in the late 1980's, and it shot terribly with jacketed hardball, the barrel literally looks like a sewer pipe on the inside, but pretty fair on the outside. Lee and RCBS 230 grain round nose cast boolits shoot fair. What is strange, is that a 250 grain .45 wadcutter shoots the X ring out with ten rounds at 25 yards when I do my part, but flattens primers.

Long way around, I may consider making lemonaide by using the Harbor Freight Black PC with .45 Round Nose Cast Boolits to smooth out the sewer pipe if it should prove to be mildly abrasive.



I sent Harbor Freight an e-mail request this afternoon for the MSDS on all 4 of their Powder Coat paints. I'll try to post the MSDS's here when I get them.

Earlier in the thread there discussion of the MSDS's for Harbor Freight Powder Coat Paints, but an inability to post them to this thread. Attached are MSDS Sheets for White, Red, Yellow, and the infamous Black Harbor Freight Powder Coat Paints.

Attachment 90719Attachment 90720Attachment 90721Attachment 90722


Click over each of the 4 docs to get pdf's for each of the different colors.