if I'm reading this right I'm seeing a partially cured coat of P/C then a coat of polymers is laid on top of that.
then the whole thing is cured together in a full bake.
the gas check is the capper for the base to square everything up when the final sizing is done.
the thickness is about the same as the land height.
now coating naked lead has my attention...
I still use gas checks for my hot Casull loads, even if I coat them.Originally Posted by BILLYBOB44
Why are you Gas Checking a .452" projectile??
With good Powder Coat you should be good for 1400-1500fps-Should be no need for gas check??..Bill.
Gas checks tend to help accuracy in my hotter loads, tends to keep the base uniform.
I put the gas checks on using the Saeco immediately when I finish casting, without sizing if I plan to coat. Then PC or Hi-Tek, then sized with a Lee push through.
__
42
I have found tech. articles stating coat/partial cure/recoat/final cure does work OK. Used for better coverage and thicker coats without orange peel/fish-eye problems. I've pushed 170 gr. GC 308W past 2700 single coated (HF red and Smoke's black) without problems so IMHO it's not necessary.
Whatever!
As far as I can tell the only reason to continue to gas check a powder coated bullet is the flat base that a gas check creates. The question remains does the flat base of the gas check perform better than the flat base of a powder coated bullet when the base is coated and cooked base down, leaving a relatively flat base? And if a GC does perform better, is that improvement worth the additional time and expense to gas check? I don't know because this will take a side by side compairson between two identical bullet designs, one GC and the other PB, and we haven't done that.
Initially when I got into PC is was to be a temporary thing to get away from lube until bullets became available again after Sandy Hook. I was only interested in the process as a lube, but then I began to observed properties that far exceeded the ability to just lubricate the bullet. These properties were of a jacketed bullet, not metal as we all accept, but something new, a jacket formed with plastic. By testing we have now found the polymer does create unique properties of a jacket and this jacket will perform at high velocity and does not leave behind metal fouling.
Now another big question we are considering is what type of polymer is the best for the polymer jacket? I started out like most intrigued by the choice of colors and the application process, but Powder Coating process uses many different polymers with different properties for different reasons. So all the powders will coat, but will have different properties. As stated by a Phd chemistry professor, polymer physics is nothing new, what is new is what we are doing with it. To my knowledge there is no empirical data available for creating the best polymer jacket for a bullet. So, we all are are the mad scientists playing around in a completely new field and we have a lot to learn. What is happening, is we are sharing our results whether they are a success or failure because that is the way we learn.
I've done it with 4 different mold designs now. In all but the highest pressure loads, the PB PC bullet performs just as good as GC'd (or at least as good as I can shoot).
This was all done with 12bhn alloy, so a harder alloy I'm sure would help avoid the need of gas checking as pressure rises. And, opposite of that, a softer alloy will likely need to be gas checked sooner.
__
42
With the boolits being completely encapsulated in PC, I think that the working pressure range of the particular BHN is significantly increased.
The PC doesn't allow the gas cutting because it does not skid on the lands, becoming wider slots along the lands and giving a space for the jetting gasses.
In my limited understanding, the lead is almost insignificant if the coating is at least as thick as the lands are tall.
TMJ and FMJ (same type totally enclosed bases) boolits have pretty soft lead cores…high velocities don't affect them so long as they are not plated rounds.
This makes me view the thickly coated PC'd boolits in the same light.
I dunnoh for sure yet…OS OK
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
OJ, you are absolutely right, it is the jacket, not the alloy. All the concern about alloy hardness is a carry over thinking with traditionally lubed bullets. We are testing 30/06 rifle bullets at 3000+fps using range lead, which is more like 8 BHN. If you look at a pressure chart a lubed bullet this soft can not withstand the shear force of almost 50K psi, but a jacketed bullet can. You are right about the need for thickness of the jacket, which better withstands the shear force. Thickness is necessary as a professor who specialized in polymer physics told us and our testing proved he was right. It is the polymer jacket that engages the rifling and is what the soft inner core is riding on, just like a metal jacketed bullet.
As you mentioned, what might help some is if they think about a copper jackets. If the jacket is electroplated, even double thickness, it has a pressure limitation because the jacket is just too thin and it will start to separate and flow at higher pressures. Copper hard, but it lacks toughness and it remains a outer casing not truly bonded with the alloy. A thicker copper jacket will withstand higher pressures, but if the pressure gets high enough it also will start to fail as the inner core will separate from the copper; this was the reason some bullet manufactures created core lock bullets.
So many are now powder coating and using a huge array or powders and the type of powder vary in their properties (hardness, toughness, temperature resistance, etc.) when cured, so results will vary due to the choice of powder. The thing we are looking at now is the polymer itself and hopefully can get some insight from professionals in that field. What type of powder is going to be the best for creating a polymer jacket for higher velocity? We pretty much know just about anything works for handguns.
I wanted to say thank you for the partial cure info you all posted. I had a non boolit project this weekend and that saved me a ton of time and made things much easier.
Wish I could take the credit, but the partial cure information I got from one of the techs at Prismatic Powder when I first started powder coating. He obviously was talking about non-bullet use, but good information that I am now putting to use.
Another time saver for non-bullet coating is to preheat the object to about 350 degrees and then spray. The powder will bond immediately and start of flow slightly on contact. Then do a complete cure.
even with a paper jacket when using smokeless powder 'the core' needs to be harder the faster you go. [higher in pressure]
the paper also has to be pretty exact in thickness with no overlap.
just like a copper jacket the better more consistent jacket will be more accurate.
the square base will over rule other damage to a bullet if the damage isn't super severe or offset the weight balance too much.
I have pulled bullets with vice grips and reloaded them with the mashed sides and was able to poke 45 out of 50 of them into a one inch group with my hunting rifle.
sorry but I still look at this as a lot of work. Much simpler to run them through my star load and shoot them. I don't shoot cast over 2000fps and conventionally lubed bullets do just fine up to those speeds. Other then saving the cost of a lubesizer (you can pick a lyman up for under a 100 bucks on ebay used) I see no advantage if your shooting under 2k. I guess it will take more then ive seen here so far to covert this old school guy.
Lloyd PC is a coating that acts as a jacket as far as the GC I have to say for Hot loads they are needed since the PC adds nothing to the hardness of the lead so deforming the base of the bullet is a concern.
Disclaimer This is my thinking not a proven fact like climate change.
So a PC bullet that has the base coated may give you a flat base which would work as a GC but on a hot load like a 454 I would have to stick with the GCs due to the high pressures.
Reloading to save money I am sure the saving is going to start soon
PC adds nothing to the hardness of the alloy, but the polymer jacket that encases the alloy is many times harder and a lot tougher than lead. When the bullet's base is coated the high temp polymer withstand the very short duration of high temperature acting as an insulator for the alloy as well as a seal.
At the present we have not fired any rounds at 60K psi that can be generated by the 454, but tests of full power loads in a 30/06 in the 48K range without gas checks do work. We do not know at what point, of if, the polymer jacket will fail, but we do know the polymer jacket does work in more traditional rifle cartridges. The question now is the accuracy of a plain base powder coated bullet vs a gas check base? This is something we plan to test at a later date, but at the present I have no molds that drop an identical bullet design except for the variation of the base. I know of no way to confirm which base would be more accurate unless identical bullets are used.
Dragonheart I was not saying the PC coated base would fail or be burned off my concern is the pressure pushing the bullet will start expanding the base more then desired. The main reason 454 copper bullets jackets are thicker then standard 45s. I do not know for a fact since I do not have the equipment to test just basing this off reloading data for the 454 and what has been outlined to use in this round. Granted I am not pushing my PC bullets at max or loading them at copper jacketed data. But I like my pistol and like my hands even more so I tend to lean towards the safe side on this matter. But again I take everything I read see and hear mull it over and base my decisions on which way to proceed from there.
Reloading to save money I am sure the saving is going to start soon
not a jacket, its a coating. Big difference. A jacket is copper and is much harder then lead and adds integrity to the bullet. This is nothing new. Reineer, berry and others have been selling these bullets for many years. So a guy would have to coat, cook, cool, size, gas check, coat, cook, water drop.. Seems like a lot of work when I can water drop when I cast and lube and size in on stroke on the star and its ready to load. Bet I can do 3 or 4 to 1 compared to this method with my star. Factor in that the powder costs more then conventional lubes and the electricity your using to bake them twice and my time is worth something, I think that after a few years the star would pay for itself. Certainly if a guy picked up a used lyman for 50 bucks on ebay it would be the cheaper and easier way to go. More I look at this the more it looks like a solution to a problem that doesn't exist.
Last edited by Lloyd Smale; 04-07-2016 at 06:56 AM.
RP, you bring up a good point and to my knowledge no one has posted any PC testing at very high chamber pressure so we don't know. Spin up torque is directly proportional to the peak chamber pressure and the very high chamber pressure of the 454 would require a thicker copper jacket, as to a PC jacket, we don't know.
I and others are in the process of developing loads to test the limits of the polymer jacket, or at least within reason. What we do know is the powder coating has definitely created a synthetic jacket with properties very different from the original coating; this synthetic jacket is actually bonded to the alloy, not just a copper sleeve encasing the alloy; this synthetic jacket is much harder that the underlying alloy and is tougher than copper; this jacket also provides thermal protection. After that there are just questions to be answered, most of which will require meticulous testing.
An issue that some may be overlooking, is that using a non-checked PC'd boo-lit that was designed for a gas check runs the risk of having an un-true (square) "gas ring", let's call it, at the base. This would have the same effect as having a bad crown on the end of the barrel. I have powder coated/cooked some non-checked boolits to find the PCing at the base would sag a small bit which would result in the poor accuracy. The ONLY reason I have messed with powder coating is for my rifle bullets which I want to run at full power loads. I have had good success with 308 PC boolits running at a high 2700 fps. using the same IMR 4895 load that I use with 150 gr. jacketed bullets. But with a gas check installed.
I currently have a "2PB 2GC" mold on the way for the 454.
Like RP said, this isn't about the powder coat failing, this is about base deformation. At least I think. I have still never recovered a bullet, only observed accuracy drop in PB bullets, but not drop in checked bullets. And, these are different bullets being compared, I don't currently have a mold that drops the same design both ways.
I can tell you from previous GC only tests, that the 454 can "skip the lands" of a PC bullet. Super Durable line of powders, and HF Red. Much wider lands cut into the first half of the bearing surface. It seems to correct itself about halfway down the bullet, which would be about the time the whole bullet is in the bore.
Harder alloy does seem to help this quite a bit as well. Why or how I'm not sure.
I'll have to go buy some j-words to be sure, but I don't recall this being an issue with the copper jacketed bullets (not plated, Casull destroys even thick plated bullets).
__
42
Loyd:
Berry's, Rainer, Xtreme, etc. all sell plated bullets, not jacketed bullets. There is quite a large difference, in both performance, and cost.
Just an FYI to others reading.
__
42
Laredo, you are right accuracy would have to suffer using a bullet designed for a gas check and not using a GC. Regardless whether powder coated or not the base of the bullet would not be flat and not round because this area would not be sized.
Posting Permissions
| BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
| BR | Bench Rest | M | Magnum | RN | Round Nose |
| BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
| C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
| HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
| PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
| LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
| GC | Gas Check |
Reply With Quote
