Testing Propellants Effect On Bullet Coatings

[igolfat8]

I had read where most propellants, containing nitroglycerin, would attack some bullet coatings so I set off to do some testing my self. I put a small amount of Bullseye, TiteGroup, Winchester Super Field and Aliant Sport Pistol powder into individual ZipLoc baggies. Next I submerged three bullets, Green is 1 coat of Smoke's PC, Blue is 1 coat Eastwood PC and Gold is 2 coats of HiTek.






The test was started on 3/18 for BE, TG and WSF powders and 3/20 on the SP powder. The bags were stored in a cool, dry, dark cabinet. I inspected each sample daily and made notes.

After 24 hours BE, TG and WSF all had flakes of powder sticking to the PC bullets. No effect on the Gold HiTek paint.

After 48 hours the gloss was gone from all PC bullets and they felt gummy or tacky. No effect on the Gold HiTek paint.

I placed a new shiny green bullet, on the right side for visual comparison. That bullet had not been exposed to any of the propellants and served as a control sample for the test.













After 7 days I was able to easily scrape off PC with my thumbnail from the BE, TG and WSF samples. No effect on the Gold HiTek paint. The pencil points to where I scraped the lead off.





After 3 weeks all the PC and HiTek bullets in the Sport Pistol propellant still retain all of their gloss and integrity and look like new:





I conducted this test because I have had issues with my pistol comps getting lead build up. What is odd is that when I shoot HiTek coated bullets I get lead deposits in the comp. When I shoot Powdercoated bullets, I don't get lead deposits. Based on this test you would think it would be the inverse. I don't usually allow my PC bullets to set (loaded) longer than a week before I shoot them so this may have an effect. I will continue my testing and allow the PC bullets to set for 3 weeks (loaded) and then shoot them to see if this will cause any lead build up. I will also make notes on how long the HT bullets have set before shooting them to see if this will have an effect on leading as well.

None the less the Alliant Sport Pistol Powder is proving to be one of my favored propellants now. It burns the cleanest and leaves the least amount of residue in spent brass and inside my pistols.

[rdwarrior]

Interesting - Next obvious questions I would have are
1) see what the base of a boolit looks like after it has been loaded for awhile and then disassembled - wondering if the lack the lack of or extremely limited amount of air in the cartridge would have any effect on what the powder does to the powder coat and
2) would a gas check eliminate any interaction between powder and coating?
Ron

[popper]

That hitek gold is more brittle than PC, it fractures and chips off easier.

[white eagle]

Interesting - Next obvious questions I would have are
1) see what the base of a boolit looks like after it has been loaded for awhile and then disassembled - wondering if the lack the lack of or extremely limited amount of air in the cartridge would have any effect on what the powder does to the powder coat and
2) would a gas check eliminate any interaction between powder and coating?
Ron

I am betting it wouldn't be a factor if a gas checked bullet was used
as far as non GC bullets I doubt that it would matter
the bullet base would all that would be effected
the base has no effect on the rifle bore

[Walter Laich]

FWIW: I have some 45 Colt cartridges, loaded for over a year now that got pulled (bad primers--another story) and sides were fine.

[igolfat8]

Hi Walter:

That is not surprising. The sides are sealed and not exposed to the propellant. Only the bullet bases are exposed to it.

[igolfat8]

the base has no effect on the rifle bore

I would respectfully disagree. The bullet base is exposed to the ignition and combustion of the propellant. If the base coating is soft and compromised then its very likely lead would be microscopically atomized and deposited on what ever is in the path of the escaping gasses, i.e. the bore and / or muzzle devices.

[sundog]

My concern would be what effect is has on the powder, not as much as the base getting exposed.

[popper]

Been shooting PB fast in BO AR, basses purposely NOT PCd. Clogs up the gas key and AGB. I've overcoated some thin PC with BLL - is stays a slight bit tackey but the PC isn't affected. If you have BLL (or an alox based stuff) try it over the PC to see if the powder does the same thing. I know, another step but it may solve the problem.

[Mytmousemalibu]

This is why in my Open pistols I have not used a coated bullet and relegate them to plated or jacketed only and the latter only with sealed bases. I really don't think to fondly about big plumes of gas being projected up right in front of my face that contain a bunch of vaporized lead. I run coated bullets exclusively in all my non-comp'd pistols otherwise. I really don't care for cleaning all the deposits out of my comp's either. Nothing about Open division is cheap or affordable, including the bullets!

[slide]

igolfat8, After seeing your post I pulled some rounds that had been loaded with titegroup powder. Some powdercoated and some hi-tek. No effect on the hitek but the powdercoat could be wiped off with my finger.Interesting! These rounds had been loaded since March 7 2018.

[GunFun]

Fascinating stuff guys.

I will be doing some similar tests with a few powder coats now.

The propellants I use with PC the most are bullseye, Green Dot, H110, CFE BLK, Blue Dot, and Longshot. I really don't know much about the chemistry of those, other than apparently bullseye is nitrocelulose based. What can you tell me?

[GunFun]

Oh, and WSF is another go to powder for me.

good to see that two of my primaries are shown in the above test.

[GunFun]

I've been considering a switch from bullseye to CFE pistol. any info on the chemistry of that?

[igolfat8]

Try Alliant Sport Pistol. It was engineered specifically for coated bullets and is a drop in replacement for Vita Vouri N320, which is probably the most popular competition games propellant. SP is half the price of N320 too.

[Nines&Twos]

I just went and pulled a 230g pc’d bullet from a 45 acp loaded over cfe pistol.
These were loaded July of 2016.
There was absolutely nothing going on. Using a knife I could only damage the coating on the base by actually digging into the bullet. The coating was not compromised in any way.

....ohh, the powder coat was a bought from Smoke right here on CB’s.

I suppose if one were really paranoid about it, you could make/buy an appropriately sized hole punch and use some quality paper to separate the base from the powder. Too much work for me though.

I set a handful of the same loads aside and will pull another in a year or so.

[Nines&Twos]

I would respectfully disagree. The bullet base is exposed to the ignition and combustion of the propellant. If the base coating is soft and compromised then its very likely lead would be microscopically atomized and deposited on what ever is in the path of the escaping gasses, i.e. the bore and / or muzzle devices.

He’s not wrong. Look at the base of any fired bullet. You can mark on it with a marker and unless it gets damaged from impact, there will be no change in the base. Atomized lead from ignition is a myth.

[Mytmousemalibu]

He’s not wrong. Look at the base of any fired bullet. You can mark on it with a marker and unless it gets damaged from impact, there will be no change in the base. Atomized lead from ignition is a myth.

Explain to me how a brand new compensator on an open gun gets lead buildup in comp ports using open base FMJ bullets? I have had that EXACT experience.

Its called gas cutting. Go poke around with other open gun shooters and you will hear the same experience repeated. In normal, plain muzzle pistols up to minor power factor open guns will probably never run into this. Change that to 9mm major open where large quantities of pistol powder are trying to be consumed in the length of 5-6in and in peak pressures akin to rifles and give that very hot gas multiple places to jet past the bullet base, iy will remove lead from the back of a bullet. Plug my open data into Quickload and see what kind of peak pressure you get with 7.8gr of Silhouette, Berry's 124gr HB/TP flat point, 1.135OAL in 9mm.

Ill give you a hint, its right about 50,000psi peak pressure.

[GunFun]

That isn't available where I live.

What are the characteristics we can search for to predict which powders will be compatable, and which powder coating powders may be less vulnerable? i.e. Most of us are using P.E. powders for powder coat, however there are other plastic compounds which are available.

My chemistry knowledge is more limited than I would like, but if this were put in terms of how I would think about things, it would be simpler.

i.e. is there a list of which powders contain nitroglycerin and which do not?

or perhaps a different thermoset powder for the coating. This is the one which I think has more promise. I would rather choose the coating which allows me to use whichever propellant I might find available or best. IMO the propellants are more prone to cost and availability fluctionations, as well as having a bigger impact on performance. So I would rather be able to choose the best propellant and just use a functionally inert coating.

Quote from some manufacturer website:
"Thermosetting Powder Coatings
EPOXY resin is a hard, impact resistant interior only formulation. For the most part, epoxy coatings are used as functional coatings for substrate protection where corrosion resistance, impact resistance, and adhesion are essential. The primary limitation of epoxy-based coatings is poor weatherability. Typical applications include industrial equipments, automotive underbody components, metal furniture and appliances.

ACRYLIC resins are typically used in the automotive industry as a clear coat on materials. Acrylic creates a smooth clear coat with very good clarity and provides a hard surface that is highly chip-resistant. Acrylic resins are used as additives to promote improved flow and leveling as well as enhanced stain and chemical resistance in polyester hybrid, polyester TGIC, and polyurethane powder coatings.

POLYESTER powder coats are the most used of all powder coatings in the U.S. market. Polyester's offer a broad application field and many different chemistries including: Polyester/TGIC (triglycidyl isocyanurate); Polyester/TGIC-free; Super-durable Polyester and Polyester Hybrids. Some Super-durable and Hybrid Polyester resin systems meet the AAMA 2604 specification.

FLUOROPOLYMER resins are top of line for exterior weatherability and UV stability in both powder and liquid coatings. Fluoropolymer powder coatings are purposely tailored for the architectural market and offer a long-life durable finish. Fluoropolymer powder coat resin systems can be formulated to meet the requirements of the high performance AAMA 2605 specification."

Of those epoxy and acrylic sound like they have promise, particularly acrylic, as I know epoxy can be brittle depending on formulation. Obviously Hi-tek is an epoxy based system and it works well. However its cost is high, and its application method favors larger batches to average out errors in technique. dry tumble is pretty hard to screw up, but wet epoxy or piglet method PC are more art than science.

[GunFun]

I just went and pulled a 230g pc’d bullet from a 45 acp loaded over cfe pistol.
These were loaded July of 2016.
There was absolutely nothing going on. Using a knife I could only damage the coating on the base by actually digging into the bullet. The coating was not compromised in any way.

....ohh, the powder coat was a bought from Smoke right here on CB’s.

I suppose if one were really paranoid about it, you could make/buy an appropriately sized hole punch and use some quality paper to separate the base from the powder. Too much work for me though.

I set a handful of the same loads aside and will pull another in a year or so.

Thank you for that report.

I have been working on a project to make a long term stock pile of all my ammo, so that I have reserves of each thing.

I want a significant supply for various reasons; one is convenience- I can go play with friends or compete any time, another is cost savings, buy and load a pile any time components are cheap, another is storage space. Loaded ammo takes up less space than components do, another is grandfathering stores against future limitations under law, another is prepping. This means my ammo has to be shelf stable. I also want my standard loads to be functionally interchangeable whether old or new, at least at normal ranges. I prefer modern powders which are stabilized, and which meter evenly, and which are less sensitive to variations in barometric pressure or temperature either when loading or firing. Each of those is a claim made as an advantage of the CFE line of products, as well as the rest of the Superformance...

Given that the bulk of it is going to be cast and poly coated, I already know that I have to plan for the ammo to shoot well as it is affected by age hardening and then age softening. Now I need to also figure for degradation of the coating & propellant combination. I am not worried about UV damage, since I don't store my ammo in glass jars outside, but chemical deterioration is an issue.