To check or not to check - That is the question

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  • Last Post 27 May 2019
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pondercat posted this 11 May 2019

Okay.  So I,m starting to get the hang of powder coating - more or less.  What about gas checks.  I have read different and opposing views on the subject.  Some say it is not necessary or needed, others say because the bullet is designed for checks they should be applied prior to coating, some say after coating (which I have tried with dismal results - however,  that was after two coats with the HF powder).  I even read where that if you leave the check off,  the cut for the check will act as small boat tail increasing the BC of the bullet slightly..

Anybody do any actual testing with and without checks? For accuracy? Bullet drop? Opinions?

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GP Idaho posted this 11 May 2019

Since you did ask for opinions I'll give you mine. Just think of PC as an alternate lube. It doesn't act as a gas check in my opinion.  As we've been told, the base edge of the bullet is the steering wheel and I believe that means a check should be used if the bullet was designed to hold one. As to before or after coating, that all depends on how the checks fits the bullet. Most of the time I apply the checks before coating. As with everything else in our craft, one size doesn't fit all. I keep an inventory of homemade aluminum checks made of material between .008 and .014 in thickness this helps with the fit when the shank varies in size. I also believe that coating after checking is just one more way of getting a firm hold of the check to the bullet. Gp

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GP Idaho posted this 12 May 2019

pondercat:  So many things we just don't know in this. Any change is going to have an effect, some small others large. I read here (poster forgotten so I can't give credit) that cast bullets were like a musical symphony , change one note on one instrument and you can sour the whole piece. Now I don't think leaving off a gas check is all that dramatic but only side by side testing using your gun will answer that question. Gp

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KeithOR posted this 22 May 2019

If it's no too far off topic are you guys using straight powder coat or adding something to it?

I'm just starting out and tried forming gas checks for the 358156 and had trouble getting the checks to stay on. And you know... the check metal needs to be annealed, or I should switch aluminum alloys, switch to brass, or maybe even make a very careful modification to the bullet mold to allow the checks to seat better in the sizer. But for now my solution was to switch to the 358429 and 358477 and I've started experimenting with powder coating. So Terry, I think we may be exploring a similar path though you are farther along.

I tried shake-on Harbor Freight powder coat, the white one. It works OK. Two coats works better. I tried adding the finest grade of alumina polishing powder to the powder coat, which what the old NRA tests recommended as an additive for wax bullet lubes, and the surface texture was not good. I shot them anyway and the bullets shoot fine. It was a one-off test, and maybe later I'll try again with different and smaller amounts of alumina in a carefully controlled test. I switched to a better commercial powder and want to try adding hexagonal boron nitride and/or molybdenum disulfide. It could be added in the mix or shaked on after the bullets come out of the oven.

I've switched to the powder coat that a guy in the bullet casting community selected after some testing. Sorry I don't remember his name but I think you guys know him already. I ordered directly from him. Initial testing with shake application looks great. I got the Eastwood powder gun and am going to switch to powder coating as my "standard lube" for a while and see how things go. I'm planning to switch to a hollow-point mold for the next batch of bullets because it seems like the easiest way to fixture the bullets for spraying is to use a metal plate with pins pressed through for the bullets to rest on. The ground clip for the sprayer goes to the metal plate and the whole plate goes into the oven. I haven't constructed the spraying fixture yet, but this is another trick I found on a forum or youtube video while searching for answers. The hollow point mold is a 4-cavity mold from MP Molds in Slovenia and works great.

Keith

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Randominator posted this 19 May 2019

I have been powder coating for over 6 years and in my tests, if the bullet is designed for a gas check then it will require one to maintain accuracy.  I prefer to seat the gas check after powder coating during final sizing.  Never had any issues with them coming off.

I have pushed some plain base bullets well in excess of 2000 fps with absolutely no leading.  The only bullet I still use a traditional lube on is my 190 grain 10mm and that's only because I haven't bought a LEE push through sizer in .401"

 

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pondercat posted this 23 May 2019

Well I don't know about being that much farther along - I'm still making a mess of things sometimes, though not so much as a couple weeks back. As far as additives to the powder coat I don't add anything and I don't remember reading anything about anyone adding anything to the PC.  It appears to be pretty much a stand alone product.  I do know that I sometimes get better results with a couple of powders I have if I shake them in a plastic container for a minute or so before adding the powder, but that is not true for all of them.  Also I have discovered that the type of plastic you use does make a difference sometimes.  Like GP Idaho said  in an earlier post:

"So many things we just don't know in this. Any change is going to have an effect, some small others large. I read here (poster forgotten so I can't give credit) that cast bullets were like a musical symphony, change one note on one instrument and you can sour the whole piece".

I think the opposite is true as well.  Change one note and everything just seems comes together in perfect harmony. And that is what I strive for.  Finding that harmony.  That is the intrigue for me.

GP Idaho seems to have a pretty good handle on powder coating techniques.  I have learned to take his advice to heart as well as others on this forum and it has helped me better understand how and why PC works as it does.  My biggest problem now is being able to find the time to test what I have learned.  Primarily, weather and work get in my way.  I have about 100 test loads all ready to go and I have built a bullet trap so I can recover some of my creations. If the weather would just cooperate. . .

Terry

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Randominator posted this 27 May 2019

pondercat,

Since I started powder coating, I have not noticed any difference in accuracy in relation to bullet hardness. In fact, I cast using less linotype and use a much softer bullet now. I don't think it is needed with powder coating. I have also changed my technique somewhat. I use to water drop everything out of the mold and allow the bullets to air cool coming out of the oven after coating. I now air cool my bullets, then water quench as soon as I pull them from the oven after powder coating. This yields a much harder bullet.

I did try multiple coats on one bullet that was undersized coming out of the mold. The accuracy with that bullet was so bad, it didn't help any. Many people use multiple coats to achieve a better finish, but appearance has no relation to accuracy. Some of the worse looking, thinnest coated bullets I have produced shot as well as the ones with a perfect coat.

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BigMan54 posted this 12 May 2019

 What GP said.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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pondercat posted this 12 May 2019

GP and BigMan. 

That all makes sense to me.  In fact, I have already experienced trying to check one bullet that was coated first.  I couldn't make it work. But on a different bullet it worked fine after coating.  On the other hand, if the check is left off and the bullet is sized correctly for your gun, would the job of "steering" simply be taken over by the rear band of the bullet?  or would the bullet fail to obturate properly? 

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pondercat posted this 13 May 2019

 GP,

Thanks for the direction in your PM to me.  Helped a lot

Terry

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GP Idaho posted this 13 May 2019

Glad to help were I can Terry. A bit of time reading up can save a lot of frustration. Gp

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pondercat posted this 19 May 2019

Randominator,

So in your experience does bullet hardness seem to be a factor in speed and / or accuracy of the bullet?  I have roughly three different alloys I typically use for different velocities and guns, but I haven't had the chance to do any real serious testing since discovering powder coating -  just a few rounds here and there.  Also, have you had any experience with using multiple coatings to augment a bullet that is slightly undersized? Just curious because I have read mention of it on other forums, but never saw where anyone has actually put that to the test.  If that works it could negate the need to enlarge molds and sizing dies.

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