Effects of scraped PC coating

[RedHawk357Mag]

I realize that any deformation of the bullet has probably zero positive attributes attributed to accuracy. Makes perfect sense. But what probably happens if the PC coating is scraped during bullet seating per misadjusted dies or less than satisfactory bullet alignment during the seating process. Would the scrape cause the surrounding PC to abraid away during it's passage down the bore? When PC fouls the bore does it retain the PC color. I am under the impression that PC fouling is difficult to remove, are there circumstances where it isn't? Thank you.

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[Taterhead]

I can't speak to the first question about abrading adjacent PC.

I can say that I've never encountered PC buildup in my guns or color, for that matter. And guns cleanup by removing the typical nitro fouling. My cast loads are exclusively handguns.

If scraping occurs, I address it so that the coating is not bothered by thr seating process.

[slide]

Another possiblity is that the coating is not cured 100%. A thermocouple in a bullet is about the only way that you find out. I know most guys go 20 mins but, you really need to know what the bullet temp is. A digital thermometer and thermocouple can be bought off of amazon pretty cheap. You can get a muti meter at wal mart that measures temp. I have used one for four years now and it has made a big difference in my coatings, both powdercoat and hi-tek.

[Bazoo]

I'm wondering if you were to remove the PC from the last driving band, would it lead the bore? With lube, the lube flows under pressure and coats the bore, keeping the nude parts of the bullet from leading. I wonder if PC does similar or if it is only the coating that is present on the bullet that has any effect.

[RedHawk357Mag]

As for the cure process...I definitely considered that. I bought a Oyster convection toaster and tested it with a Taylor vial thermometer and a digital thermometer. All three agree and the digital pretty much says it holds a constant 400 during my heating process. 250 to 300 bullets, standing on a porcelain tile takes roughly 15 to 20 minutes to hit air temp of 350. At that time the PC starts flowing. I don't start the 20 minute count until 400 degrees is hit. I pull at 20 minutes and let it cool. I size and test using a smash test and and rub test with Xylene and Q tip. Both performed as expected.
With a different gun my same process worked readily well used on previously lubed bullets. I expected less than optimum results due to previous lube residues. Three bakes, and two washes in acetone apparently was enough to get a satisfactory coatof PC.
I plan to test similar loads in a different gun tomorrow with a significant emphasis on bullet alignment in cases. Will post an update to this later. Thanks

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[popper]

You get leading!

[Boogieman]

If we are curing the PC and bonding it to the surface of the Bullet why would the internal temp, of bullet make any difference?

[slide]

It is the best place to put the thermocouple. There is very little difference in the middle temp and the outside temp. I suppose you could attach the thermocouple to the outside of the bullet. Remember, the instructions say 400F for 20 minutes PMT. The PMT stands for part metal temperature. The part has to get to 400 F before you start the time. Most of my powders are 10 minutes at 400F. Some guys use an IR gun but you will get crazy readings with it. Oven thermometers and other thermometers tell you what the air temp is in the oven. A lot of guys make it work. The thermocouple method is just another option.

[popper]

Usually the base gets scraped when seating from 'misalignment'. Probably get gas cutting and some leading. You cooked properly, just bell case mouth and seat carefully.

[RedHawk357Mag]

Slide, on this modification you have done to your thermocouple did you use just one bullet or did you put a number of them on there? Mine are probably about ten inches or so. Not sure exactly where it actually reads from. Thanks.

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[slide]

You can buy a digital thermometer that has multiple thermocouples. I just use one and lay it in the middle of the of bullets with hi-tek and in the edge with stand up powdercoat. Are you talking about one of those metal thermocouples? If it is metal it will read from the tip. The ones I use are wire encased in hi temp coating of some kind. Check them out on amazon. Cost you around twenty bucks.Another option is to go to walmart and buy what is called a multi meter. It measures temp and comes with a thermocouple. Make sure it will measure the temp range you want. I drill a small hole in the base of the bullet and put the thermocouple in the bullet and secure it with high heat aluminum tape. Not pretty but it works. I have one I have used for close to four years. It hasn't come loose yet. I am in Ardmore and am over that way once or twice a month. If I can help let me know through pm.

[charlie b]

If you scrape some PC from the bullet you can get leading. Just like removing part of a copper jacketed/plated bullet.

You will not scrape off PC if your loading setup and all dimensions are correct. You may need to flare the case mouth a bit to make sure the bullet goes into the case straight. With gas checked bullets and carefully placing them just the camfer on the case mouth can be enough to prevent scraping them.

No, the PC does not usually retain it's color as fouling in the bore (I have looked with magnifiers, both in the bore and on patches). Every now and then I have seen a flake of PC when cleaning. I suspect it is some that has fallen off the base of the bullet. Usually any residual PC in the rifling is very small in size and is embedded in the bore. I use Ed's Red for bore solvent. The acetone in it will attack PC so I suspect it helps when cleaning the bore. I only clean every 100 or 200 rounds in the rifles.

[charlie b]

Temperature measurement is however you want to do it. The PC is dependent on the surface temperature of the bullets.

But, measuring the inside temp of the bullet is sufficient in the time factors we are using. The time it takes to heat the interior of the bullet is measured in several minutes, not tens of minutes. If you are using large batches of bullets you can put a thermocouple in the center of the batch of bullets and it will probably be more accurate than a TC inside a bullet, BUT, the difference is minor. Yes, having a TC on the surface of the bullet would be better....maybe, depending on the type of TC used and relative surface areas of the TC and the bullet.

This is all nit picking. If you are doing large batches (like bucket loads) you need to know what the temp is in the center of that batch. If, like me, you are doing fewer and they are spaced apart on a pan, then tracking the air temp in a small oven will work fine, as long as you know the temp and do not rely on the oven dial markings.

[RedHawk357Mag]

Thanks Charlie B for that informative write up. I figured out the misalignment issue today. I have been using a Redding Micrometer seating die and the bullet stem is concave. It is wider and deeper than say the standard RCBS bullet stem for bullets like 358311. I thought that the SWC would have no issues due to the size. Turns out that was incorrect thinking. I have one of the Hornady Cowboy die sets and it has interchangeable bullet stems, loaded the flat stem and SWCs seated just fine. It's a shame that it took this long to figure out. I think this has been going on for awhile giving me excessive lead buildup in my throats. I believe that it's been shaving that tiny sliver fairly often most often rolled into crimp groove during the crimp. Mixed with lube it got sprayed onto the throats. Also funny that I went through all my 357 expanders today looking for something different to help the issue.

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