Question on PC coating

[M3845708Bama]

Has Anyone found any difference in shooting the different colors of the Poly Powder PC or do all the colors shoot the same with a given load?

Also do these powders all coat the same thickness ( in one shake and bake sequence or do certain colors coat heavier then others?

Don't know about anyone else but from my experience there is a difference. Smokes blue coats the best and thickest of any I have found. It uses a cross linker to causes the powder to cross link and take the final set when cured. I was trying to develope a fairly HV accurate load in 308w. and it worked very well with the exception that with the particular bullet (bore rider with sized long nose) and gun combination the accuracy would drop off after 12 to 15 shots. That really bothered me so I started looking at all the possibilities. I started looking at the components of each PC color. I found that the companies would not give the exact % of each but would give the max percent by chemical for the polyester resin and color combination. (CAS breakdown) the majority of the color components have a melting temperature of 1580 to 1840 degree C so they should not be a problem. The polyester and cross linker melts at 95 to 98 degree C. I made a spread sheet and then looked at the ratios. The ratios of polyester and cross linker compared to total wt ran from 5% to 15%. If the cross linker was the problem I figured that the color with the least amount in it would or should give the least problems. My tests indicated it was the correct assumption and since that time I have pretty much only used "Bacon Grease". It is not the prettiest color but its performance makes it really pretty to me. It has good coverage-not as thick as signal blue but is adequate for anything I have found and accuracy usually is maintained through the 50 rounds I normally shoot in a session.I would be glad to help you in any way I can. I do not think we have scratched the surface on what is possible with cast and PC.

 

[358156 hp]

My Carolina Blue powder from Smoke will creep in between the bullet and a gas check, making installation rather permanent. Even Lyman checks. Gloss clear also works really well, and covers smoothly.

 

[JWFilips]

I have the Smoke's Gray powder as well as the Clear. (I don't even think he has the gray listed)
However I mostly use the clear coat.
Is there a difference in the material after heating between these? Are these cross linked powders?
M38457708 Bama: that spread sheet you created sounds like a treasure! Is this something you would share here?
Thanks
Jim

 

[M3845708Bama]

I have the Smoke's Gray powder as well as the Clear. (I don't even think he has the gray listed)
However I mostly use the clear coat.
Is there a difference in the material after heating between these? Are these cross linked powders?
M38457708 Bama: that spread sheet you created sounds like a treasure! Is this something you would share here?
Thanks
Jim

Will have to figure how to get it on forum

 

[JWFilips]

I'm sure you could just upload with the "attach Files" button

 

[fiver]

yeah that was a great addition.
at the worst taking a pic and sending it by text or e-mail to someone else might work too.

 

[M3845708Bama]

OK I am going to try to attach it--sure you will have questions, Will try to walk you through it. This will be the summary sheet that covers the main colors at the time the analysis was made the main points are the ratios of the cross linker to resin. My thoughts are if powder will work--cross link with 5% cross linker the if you add 10% that is 5% of low melting material. Also if you add the cross linker to the resin the ones with the lower ratio of these two should have less potential for gassing and causing any problems if pushed hard. Just my thoughts, but it has worked for me so far.

 

[JWFilips]

Fantastic, Opens fine for me but you do have to download "Linked file" first to get it on your computer
I'm sure I will have some questions but this info is great
Thank You!
Jim

 

[Ian]

Wow, real science! I haven't seen it broken down like that by component and the barrel fouling has always concerned me. The only time I've seen the fouling is with PBTP Kawasaki Green (350°F specified cure temp, polyester powder with TGIC cross-linker) in my suppressed 1911 with a rough, mellonized aftermarket barrel, and in my Socom barrel when I had too much case tension causing under-groove size of three out of four driving bands (read: Massive blow-by evidence by crusty lead/pc fouling and clear evidence of gas-cutting on recovered bullets, also sideways bullets at 25 yards. So, excess abrasion and undersized bullets will "PC foul" same as lubricated lead will.

I do have a question, even in light of the empirical data regarding less fouling with less cross-linker in the coating formulation: Is the cured coating equal to the sum of its parts? I don't think so because a permanent chemical change takes place which alters the characteristics of the whole coating.

I'd also add that, as anyone who's remelted coated bullets in their casting pot can attest, the poly coatings turn to chewing gum at about 600°F, and is only harder than lead alloy at room temperature, so we can expect it to behave similar to lead or copper within a rifle barrel.

One more thing: I'm exploring adding lube to the grooves of PC bullets and also using liquid coatings such as BLL to mitigate the abrasion leading at HV. So far I've put about 30 rounds at 2175 to 2290 fps through my .30-30 Savage with PC, gas check, and lube with NO fouling accumulation. Over 50 rounds without anything but a dry patch through my .35 Remington at ~2100, also with zero harmful plastic accumulation (PC, GC, and lube). .45 Colt loads in my Henry and NEF both total in the hundreds with mix of lubed lead, PC, and lubed PC plain base bullets at ~1K fps and zero fouling in either of them. With the PB loads at lower speeds I get more significantly more velocity (~10%) when lubricating the coated bullets, and I get quite a lube star (actually lube "tendrils" projecting from the crown) even with a normally "disappearing", dry, soap-based lube.

 

[M3845708Bama]

Wow, real science! I haven't seen it broken down like that by component and the barrel fouling has always concerned me. The only time I've seen the fouling is with PBTP Kawasaki Green (350°F specified cure temp, polyester powder with TGIC cross-linker) in my suppressed 1911 with a rough, mellonized aftermarket barrel, and in my Socom barrel when I had too much case tension causing under-groove size of three out of four driving bands (read: Massive blow-by evidence by crusty lead/pc fouling and clear evidence of gas-cutting on recovered bullets, also sideways bullets at 25 yards. So, excess abrasion and undersized bullets will "PC foul" same as lubricated lead will.

I do have a question, even in light of the empirical data regarding less fouling with less cross-linker in the coating formulation: Is the cured coating equal to the sum of its parts? I don't think so because a permanent chemical change takes place which alters the characteristics of the whole coating.

I'd also add that, as anyone who's remelted coated bullets in their casting pot can attest, the poly coatings turn to chewing gum at about 600°F, and is only harder than lead alloy at room temperature, so we can expect it to behave similar to lead or copper within a rifle barrel.

One more thing: I'm exploring adding lube to the grooves of PC bullets and also using liquid coatings such as BLL to mitigate the abrasion leading at HV. So far I've put about 30 rounds at 2175 to 2290 fps through my .30-30 Savage with PC, gas check, and lube with NO fouling accumulation. Over 50 rounds without anything but a dry patch through my .35 Remington at ~2100, also with zero harmful plastic accumulation (PC, GC, and lube). .45 Colt loads in my Henry and NEF both total in the hundreds with mix of lubed lead, PC, and lubed PC plain base bullets at ~1K fps and zero fouling in either of them. With the PB loads at lower speeds I get more significantly more velocity (~10%) when lubricating the coated bullets, and I get quite a lube star (actually lube "tendrils" projecting from the crown) even with a normally "disappearing", dry, soap-based lube.

With the bacon grease, I have not seen it go to bubble gum when remelted. It seems to just turn black and pretty well retains its shape like an egg shell. It may be that with the lessor amount of polymer in the mix makes it a little stronger. I have looked but have not been able to find any of the properties given for the cross linked material. One interesting thing I have notice is slightly differening hardness with different batches from the same powder supply. Sometimes it feels slightly sticky sometimes like a piece of polished steel. I use two oven thermometers any usually run for 35 minutes at 400 degrees to allow for bullet heat up to curing temp. I also water drop at end of cure cycle into an ice water bath.

 

[Ian]

Is the "bacon grease" color a Polyester TGIC?

 

[M3845708Bama]

Is the "bacon grease" color a Polyester TGIC?

Is the "bacon grease" color a Polyester TGIC?

Is the "bacon grease" color a Polyester TGIC?

I believe it is the cross linker is 1,3,5-triglycidyl isocyanurate 2451-62-9-10 This is the one that should be treated with care and respect,

 

[popper]

I covered a single light DTPC (smokes red) with ond coat BLL on a 185gr GC RDish bullet pushed to 2k fps in 308W carbine, NO fouling. Felt a little tackey - they were coated & loaded a while back and alloy was soft so accuracy wasn't great - also gusting to 30.

 

[JWFilips]

M3845708Bama: I have been looking over your spread sheet which I think ins a great piece of work! Thank you for posting.
In your opinion; do you feel the clear has worthwhile properties or would you say the Sul Yellow and Bacon grease are the better way to go with higher resin/ agent ratio for best one coat coverage?

 

[Rick H]

I shake and bake....don't put it on as heavy as it appears in your photo. I size and install gas check after the baking...only one coat. I use a lot of plastic BB's in mine and don't show the base dents that you have. I shake and bake as soon as done casting then size. Usually all on the same day. I use the Lee style push through sizers.

 

[M3845708Bama]

M3845708Bama: I have been looking over your spread sheet which I think ins a great piece of work! Thank you for posting.
In your opinion; do you feel the clear has worthwhile properties or would you say the Sul Yellow and Bacon grease are the better way to go with higher resin/ agent ratio for best one coat coverage?

The Bacon Grease is only 5% and gives a complete one coat coverage in my experience. In several cases I kelp record of the patches required to get barrel to same degree of clean. Bacon grease 5-6. Other 24-36. But this is using bore tech which does clean

 

[Ian]

The question of whether using traditional lube in a groove with PC at HV will eliminate the PC fouling is one still on my mind. Bama, I know you're using "slicks" and have to wonder if not having any lube to go along with that is causing your fouling. As I wrote previously, my 30-30 with a brand-new barrel with PBTP blue PC bullets, gas checked, two grooves lubed, has caused essentially zero bore fouling other than the normal light carbon haze.

 

[M3845708Bama]

I have been using electrical wire pulling lube which is water soluble wi th good results. The one that has shown the best results is one made by “Ideal” and is yellow 77. I wash after sizing with a water hose and then rinse in hot n water and dry with a heat gun before pcing. It seems to increase the charge so I have to tap the bullet on the side of bowl to remove excess. Adhesion of pc does not seem to be affected and all have passed the hammer test with no failures.

 

[popper]

Ian, single coat of BLL over PC (308W) and bore is SHINY, not that ist isn't with just PC. I do think I need to clean the BO barrel as I made a lot of dirty holes in paper when shooting a bunch of jacketed. But I've been using some cfeblk & cfe pistol that does run kinda dirty. Couldn't tell you when i last cleaned it, but this is target.

 

[Bruce Drake]

I've converted my brain over to PC being the first choice for my cast bullet rifle shooting. Much cleaner shooting and the process is very simple once you get past the "mystique" of it all.

Bruce