Christmas Bullets & plain base at 2400 fps

Standard Member

mckg posted this 26 December 2015

Painted Teflon? You're not getting away with a picture and your good looks you know...:)

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CBA Member

Ken Campbell Iowa posted this 26 December 2015

impressed i am . looks like lots of support and no nose rubbing . what does the throating look like ??

more more more .

ken

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CBA Member

mtngun posted this 26 December 2015

Sorry to post and run but I had to go eat Christmas dinner. :D

I was testing several coatings today and the candy cane bullet was:

-- 62 gr. plain base, air-cooled WW -- 1 thin coat polyurethane -- 2 thin coats VHT rattle can white epoxy with bullets standing on nose so base gets coated (I believe it is important to coat the base). -- oven cured at 300F to harden the coatings. -- Rooster HVR lube (no longer available, unfortunately :() -- nose sized so that front band is 0.2415", then push-thru sized 0.246" -- 26 gr. WW760 powder -- CCI #41 primer -- seated right at the jam point -- Contender carbine with Shilen 1-10” bull barrel

The reason for the 1st coat of polyurethane is that the rattle can epoxy does not stick to the bullet very well, but polyurethane sticks like glue. So I used polyurethane as a primer coat to give the epoxy something to stick to, and it seemed to help.

This lot of #41 primers I'm using has about 1 out of 10 duds hence only 9 shots on this target. I'm told this is a military primer which may explain why we can't seem to win any wars! :X I bought them during the peak of the primer shortage when you had to take whatever you could find.

No I can't do it every time but I was pleased just to shoot any kind of group. When I first started messing around with PB in this barrel they wouldn't even stay on the target above 2000 fps. Coating bought me an additional 200 - 300 fps before they started to shoot wild again, then using lube in addition to the coating has bought me another 100 - 200 fps. I'm not sure where the limit is, I've been gradually working my way up and it's taken me several months to get this far.

More later.

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Standard Member

mckg posted this 26 December 2015

Thanks!

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CBA Member

mtngun posted this 26 December 2015

For comparison these two groups show how my coated bullets began to fail as I increased the velocity. These coated bullets had a thin coat of 45/45/10 tumble lube, and that helped, but even the tumble lubed bullets began to shoot wild as velocity increased.

By switching to a “real” lube all of my various coatings at least shot a group at 2400 - 2500 fps instead of a pattern. So yes, coated bullets may benefit from a lube if you push them hard enough.

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CBA Member

billglaze posted this 26 December 2015

Mtngun: Congratulations are definitely in order! Looks as if you've discovered something worth watching. I'm going to be watching this thread with great interest, along with reading Ken's always informative questions. Please, both of you, keep us advised of further results.

Bill

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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CBA Member

mtngun posted this 26 December 2015

Thanks for your interest, Bill Glaze. Sometimes I wonder if I am the only one crazy enough to be interested in this stuff. :D

Some more data rolling in as I crunch the numbers and process the photos. Here's a pictoral summary of today's results comparing coatings and alloys, all with the same powder charge.

"MR” = “mean radius” computed using Taran software.

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CBA Member

RicinYakima posted this 26 December 2015

Speed and reasonable accuracy? I'm watching also.

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CBA Board

John Alexander posted this 26 December 2015

mtngun,

Terrific! Finally something different that looks like it has a lot of promise.

You mention that it was from a T/C carbine. What accuracy with match grade jacketed bullets? What length barrel? Do you have an estimated velocity for say a 26"?

You have a high percentage of bullet length engaging the rifling so maybe it doesn't make any difference but depending on what is limiting velocity with accuracy, would a slower twist raise the bar?

I think a lot of people are looking forward to your further reports. I know that I am.

John

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CBA Member

mtngun posted this 26 December 2015

John, this barrel has yet to experience a jacketed bullet.

27” barrel if I remember correctly, so yes I am “cheating” by using a long barrel which means less pressure and less acceleration is required to achieve the velocity. Nonetheless it is still spinning so many RPM.

I suspect a slower twist would help and I am building a 1-14” 6mmBR bolt gun, stay tuned. Just depending on what is causing the bullet to fail, of course. A slower twist should reduce dispersion due to imbalance and it's safe to assume that our cast bullets are never perfectly balanced. Harold Vaughn does an excellent job of explaining the effect of twist on accuracy on page 170 of “Rifle Accuracy Facts,” and as you know slow twist barrels rule in 200 yard jacketed benchrest. Typically 1-13.75 or 1-14 for the 6PPC and 1-15 to 1-17 for the 30BR.

But a slow twist won't help with gas cutting, base melting, yawing, etc.. My water tank tests are on hold due to Old Man Winter so I can only guess at what is causing the bullets to shoot wild, but my guess is that the base is melting and gas cutting, the coating protects the base from melting, and the lube acts as an o-ring to reduce gas-cutting. Just a guess. .>

As always my progress is slow due to time limitations. I'm still waiting on NASA to approve my grant for cast bullet research so I can quit my job and experiment full time. :D

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CBA Member

mtngun posted this 26 December 2015

Some Lyman BoreCam photos after shooting today's loads. My procedure for taking BoreCam pics is to run one dry patch through to push out unburnt powder residue before inserting the BoreCam, you have to do this otherwise the unburnt powder residue gets the BoreCam pickup & mirror dirty and it's a pain to clean. Other than the one dry patch this is how the barrel looks at the end of the test.

None of today's ~ 2400 - 2500 fps loads fouled significantly, some were just shinier than others.

I think this is after the powder coat + HVR load, squeaky clean.

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CBA Member

Lee Wiggins posted this 27 December 2015

Impressive!!! Have you tried shellac as the primer coat ? Dries in a minute . Or maybe just 2 or 3 coats of shellac them lube. I thought of trying that myself , but haven't yet. Lee Wiggins

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CBA Member

mtngun posted this 27 December 2015

I haven't tried shellac, wouldn't think it would be particularly tough, but the only way to know for sure is to try it. :)

The workings of of coated bullets is still bit of a mystery but we can postulate that the ideal coating should be:

-- easy to apply -- affordable -- adhere well -- tough -- resist melting or burning -- resist creation of polymer fouling

I still have many questions about coatings. Lots of coating posts on the internet but mostly limited to “my coated bullets are prettier than yours” or “my coated bullets go bang without fouling my barrel.” :P Serious data is scarce. The CBA has a tradition of doing serious testing not just bs so I try to maintain that tradition. :)

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CBA Member

Lee Wiggins posted this 27 December 2015

My take on the powder coated bullets or coatings of any kind is the color variety. The color added to the coating material is likely abrasive. Titanium dioxide for white,maybe iron oxide for red , etc. I am guessing about this but caution tells me to try only clear coatings (no coloring agents) . Why add to the barrel wear, Hart barrels don't come cheap. Someone out there that knows a lot more than I do about what goes into paint to get all the different colors , please weigh in. My concerns may be groundless, but maybe not. Lee Wiggins

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CBA Member

RicinYakima posted this 27 December 2015

In reference to the article I wrote for The Fouling Shot, the first priority will be to design and have built a mould of the proper size. Coatings are about 0.004” so having to work the bullet to proper size prior to coating or resizing the whole thing can be dealt with properly. Post-coating sizing requires very finely polished dies, as while the coatings “stick” the base lead underneath can be torn away.

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CBA Member

mtngun posted this 27 December 2015

Lee, you are right about the powder in some paints (and presumably powder coat, too). I used to work for a company that made CaCO3 powder, one of their customers was a paint manufacturer. But most of their powder was sold to paper mills -- it's what makes paper white, so think about that next time you paper patch. :coffee

That said I doubt it you would see appreciable barrel wear due to the powder in coats or paper patch. There is much more wear due to heat and corrosion.

Re: sizing. Yes some coatings with marginal adhesion can rub off while sizing, and also while seating. But if the adhesion is that weak you probably should find another coating, anyway. Hi-Tek and rattle can epoxy both have marginal adhesion. Rattle can enamel was the worst, to the point of being a lost cause. Polyurethane sticks like glue -- since it basically is a glue -- the downside seems to be that it's a bit “gummy” in the barrel and can cause polymer fouling, though using a bullet lube seems to address that.

Otherwise it does not hurt to size the oversize coated bullet in a smooth push-thru die. Some of my coated 6mm bullets have been 0.249” before sizing. Because I'm a crazy experimenter I'm going to be doing some experiments with extra thick coatings just to see what happens. :shock:

In the meantime if you have a mold that throws undersize bullets, or an undersize nose, coating gives you an option to turn them into correctly sized bullets.

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CBA Member

gpidaho posted this 27 December 2015

mtngun: In testing, do yourself a big favor and drop the tumble lube method of powder coating. That method is just fine for pistol rounds that are shot slow and at close range but not even coverage enough for HV rifle. An electrostatic gun doesn't cost that much. Lee: The abrasive effects of PC have been tested by many, myself included and have found to be unfounded. Most casters use alloys consisting of range scrap and old wheel weights with all the grit imbedded then worry the slick PC coating is doing damage. One of those common knowledge things John A. speaks of. Ric mentions a good point. You need to flare your brass more than your use to so you don't scrape the coating when seating the bullet. I flare the case mouths .008-.010 for coated bullets. mtnguns tests are proving more successful than most using epoxy. I'm glad to see his tests showing promise for HV. For those of you who have any interest at all in coated bullets there is five years+ of testing available for your reading pleasure over at “Boolits” Believe me, most everything you can think of has been tried with results from dismal to eureka. Read up you'll be surprised how mush has been tested. Gp

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CBA Member

mtngun posted this 27 December 2015

GPIdaho, you're surely right that a spray creates a better quality powder coat than the shake-n-bake method, and I will buy a ES gun (or possibly a tumbler) if I become convinced that powder coating provides results superior to other coatings, but so far I have not seen it.

"There is five years+ of testing available for your reading pleasure over at “Boolits” Believe me, most everything you can think of has been tried with results from dismal to eureka. Read up you'll be surprised how mush has been tested.”

You're trying to sell "Boolits” to the wrong person. I was one of the original supporters of “Boolits” after it left Yahoo and struck out on its own. It would not be much of an exaggeration to say that Boolits might not exist today without my support. There are reasons that I stopped contributing there.

I've read many of the coating posts on “Boolits” and elsewhere. It's wonderful that people are experimenting and I salute them. It's unfortunate that their experiments are poorly controlled and quantified. Most of the coating posts are along the lines of “my coated bullets are prettier than your coated bullets” or “my coated loads went BANG without leading the barrel.” If you're looking for meaningful data, it's not there.

One of the few “Boolits” coating posts that offered any meaningful accuracy results was for VHT rattle can epoxy. Even in that post, the individual showed no pictures of targets, didn't say how many groups he shot, and sometimes contradicted his own accuracy claims.

When someone on the internet says “my rifle shoots such and such accuracy” I take it with a grain of salt. Is he talking about a 3 shot group or a 10 shot group? 50 yards or 100 yards? Is it a “lucky” group, or is it the average for all his groups? Does he post pictures of the targets? Does he shoot in CBA, IHMSA, NRA, or other competitive matches? Please SHOW ME THE DATA.

When I mentioned that some coatings scrape off when seated, that was due to neck tension. Of course I flare my case mouths with an M-die or equivalent. But the ideal coating should not scrape off even if handled carelessly. I have to be very careful with the VHT epoxy bullets to avoid scraping, other VHT users have reported the same thing.

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CBA Member

gpidaho posted this 27 December 2015

mtngun: It's most certainly not my intent to sell “Boolits” to anyone and like any forum folks tend to come and go. With very few exceptions the friends here at the CBA conduct themselves as gentlemen and keep their egos in check. I tend to glean what knowledge I can from other forums and pay special attention here. As to the color of the PC, I could care less, that is just an aside of the process. If one wants to avoid some self-perceived problems with color ingredients just use the clear and you can tell others “It's my own special hard lube” I would very much like to contribute pictures of targets and groups shot but knowing my own limitations due to some physical disabilities I'll defer to others as my bench ability could prove John A. Joeb and riciny all make poor rounds if shot by me.lol This in no way keeps me from seeking the best of methods to find what works best for ME. Thanks to all for all your help. I look forward to your posts mtngun and hope you find a way forward in our craft, HV being the carrot on the end of the stick. Gp

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CBA Member

mtngun posted this 03 January 2016

Update: today we retested the same loads shot last week, only with much thicker coatings. I just wanted to see if the coating thickness made any difference. On the one hand if coating reduces melting and gas cutting then perhaps a thicker coating would reduce melting and gas cutting even more? On the other hand to the extent that coatings are uneven -- and shaked coatings can be significantly uneven -- that's liable to unbalance the bullet and increase dispersion due to imbalance, particularly at higher velocities. The only way to know is to try it. :)

Last time I tried 1-coat powder coat using the dry shake with BB's method. This time I used 2 coats, and it turned out about 0.0015” thick (the bullets were 0.245” - 0.246” before coating).

I attempted umpteen coats of VHT epoxy, but when I went to oven cure after the final coat, it bubbled and melted, so they were not included in today's test. I've oven cured this coating before without issues so I'm guessing these bullets still had too much solvent trapped inside and it boiled and made a mess.

Umpteen coats polyurethane on gas check bullets. I hadn't tried coating gas check bullets before, it's not clear if there is any benefit since the gas check may serve the same purpose as the coating ????

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Christmas Bullets & plain base at 2400 fps

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