Hardness of boolits for powder coating

[bigted]

What hardness is required for powder coating boolits?

Wondering about where the base BNH is from pure to hard mix

[mannparks]

I don't think there is a requirement of hardness but when you bake the bullets in a 400° oven you will lose some of the B. hardness probably around 2 to 3 hardness number.
Most of my bullets are wheel weights and they drop out of the mold into a water Quench and they run any where around 14 / 13 BHN.

[bangerjim]

Hardness has nothing to do with powder coating.

And yes, most if not all WD hardness is lost during your PC bake.

Some on here PC pure lead with (I guess) excellent success. Not me.

I personally mix all my alloys for 9-12 air cooled and then PC and shoot in everything from simple 9mm to 357 and 44 MAGS. And in all my lever carbines.

banger

[bigted]

Rite on. I wondered is all as I am an avid percusion revolver shooter ... I have pure lead and wondered if there were any who PCed pure lead boolits.

Probably won't waste my pure lead tho cause it is required for my revolvers.

[flyingrhino]

I got my Cabine Tree hardness tester today so i decided to play with it a bit. Interesting results. Using range scrap, ingots measured 5.5BHN. Air cooled boolits measured the same. Water dropped measured 11. When PC'd they drop to 7-8 BHN. I tried soaking some pc'd boolits in my convection oven at 430 (as hot as it would get) for 1 hour then water dropped them. They still measured 7-8. I also soaked a water dropped non-pc'd boolit for an hour then water dropped it. It started out at 11 and ended up at 7-8.

[Dragonheart]

Flyingrhino, If it helps I have fired PC pure lead 45 ACP 185 grain bullet just to see. The bullets took the rifling with no distortion other than the rifling marks, the coating stayed intact and left a completely clean barrel at book maxium charge. I did not chronograph the load as my intent was to trap the bullets for examination, but the book listed 1100 fps for the load. Your BHN numbers agree with mine as I shoot range lead also.

I think what we are finding is the PC forms into a jacket so the BHN/Pressure Chart developed for conventional lubed bullets just does not apply, as the alloy is bonded and riding on this polymer jacket, similar to a jacketed copper bullet, so the BHN is not important, at least not at handgun velocities.

The question now is at what point does, or if, BHN of the alloy matter with PC bullets and the effects on accuracy, but it appears we are now into rifle velocities. Recently another tester I am working with in CA test fired range lead PC bullets at 2400 fps, still with no leading, no keyholing and with an intact powder coat. Unfortunately, this was just a PC velocity test and no accuracy tests were made. As we learn more or form hypotheses on what we have learned I will keep interested parties informed.

[flyingrhino]

Flyingrhino, If it helps I have fired PC pure lead 45 ACP 185 grain bullet just to see. The bullets took the rifling with no distortion other than the rifling marks, the coating stayed intact and left a completely clean barrel at book maxium charge. I did not chronograph the load as my intent was to trap the bullets for examination, but the book listed 1100 fps for the load. Your BHN numbers agree with mine as I shoot range lead also.

I think what we are finding is the PC forms into a jacket so the BHN/Pressure Chart developed for conventional lubed bullets just does not apply, as the alloy is bonded and riding on this polymer jacket, similar to a jacketed copper bullet, so the BHN is not important, at least not at handgun velocities.

The question now is at what point does, or if, BHN of the alloy matter with PC bullets and the effects on accuracy, but it appears we are now into rifle velocities. Recently another tester I am working with in CA test fired range lead PC bullets at 2400 fps, still with no leading, no keyholing and with an intact powder coat. Unfortunately, this was just a PC velocity test and no accuracy tests were made. As we learn more or form hypotheses on what we have learned I will keep interested parties informed.

I agree with you. I've been shooting PC'd bullets for about 2 years now. I shoot 45, 9, 38 and 300 blackout. All PC'd. Pushing my Blackout to 1900 FPS or so but with a GC. Accuracy is excellent in all and barrel fouling is minimal as compared to lubed bullets. I have recovered several 45 cal 200 SWC that I shot into a pile of wooden pallets and the PC was perfectly intact. I just found the hardness test results interesting. PC'ing reduces the hardness gained from water dropping from the mould but forms a nice jacket that protects from leading.

Now....there are those that will say they get no leading from wax lubed bullets and see no reason to PC. To each his own. The reason I started PC'ing is that I was tired of the smoke and residue left behind from wax lubes. Also, I reload for a few ladies and they love the pink bullets. I just plain like the PC! Yes, it is much more labor intensive, and I shoot about 1000 rounds per month so it keeps me busy. But it's part of the hobby and I enjoy it.

What I have yet to do, and is on my list, is to run some of these 200grn SWC's through my 460 Rowland. This will really put the PC to the test. It will be pushing that to around 1400 FPS. So far I have only shot jacketed through it. I want to see how the PC'd lead holds up to that kind of velocity and what kind of fouling I get. For that test I need to mix up some home made ballistic gel that will hopefully stop the bullet. My 460 is for hog hunting. I'd really like to run the cast bullets through it if they can hold up to that kind of velocity and still perform on the other end.

[Dragonheart]

I think you will find the polymer jacket will hold up without a problem, as we have now tested the PC at velocities over 3100 fps with a gas checked bullet; next will be tests without gas checks. At the suggestion of our retired chemistry PHD, the polymer coat should be .002+" thick at the interface of the lead and polymer as it may really enhance the flexibility of the coating.

[Tenbender]

So I guess I don't need an 18 to 20 bhn PC'd boolit in my 357 Max on a whitetail ?

[Dragonheart]

I haven't had the time to run accuracy test on soft lead, but I now know the polymer jacket protects the barrel from leading and shows no sign of separation at higher velocities; that was the first step. In the future I will be loading soft lead PC bullets and see how the accuracy goes. In handguns I have gotten excellent accuracy from PC bullets using range lead.

[Wardo1974]

For what it's worth, I PC with pure lead boolits in my .38-55 and .45-70 for hunting loads.

The .38-55 load is about 1700 fps, the .45-70 1500-1600.

1.) Neither of them foul the bore in any way.
2.) Accuracy for each, with open sights on 100-year-old rifles, is about 1.5-2" at 50 yards. Just fine for my needs.
3.) The PC remains firmly adhered to the lead. Even when shot into blocks of firewood, the recovered (hugely expanded) boolits still have their PC attached.

So from my experience, PC on pure lead boolits works great. I shot a bear this fall with pure lead PC'd .45-70 boolits - it died!

[blikseme300]

I think you will find the polymer jacket will hold up without a problem, as we have now tested the PC at velocities over 3100 fps with a gas checked bullet; next will be tests without gas checks. At the suggestion of our retired chemistry PHD, the polymer coat should be .002+" thick at the interface of the lead and polymer as it may really enhance the flexibility of the coating.

I agree that PC works well even at high velocities but the gotcha is with CB's that won't chamber when the nose diameter is too large. I have done some testing using the 311041 in Marlin 336 where after coating the diameter on the driving bands had increased by .0012-.0015" after a single coat. The nose has light rifling marks after chambering but as the alloy is quite soft this caused no trouble. Accuracy is good at around 2100ft/s with clean barrel so a thin coating work in this combination. Testing after a double coat required some force to chamber as the nose diameter was too large.

I don't consider PC as a lube replacement but as an extremely effective barrier between the CB and the barrel that allows higher velocity with softer alloy than conventional lube. For me this is a win-win as my goal is to craft the best hunting round from my chosen platform.

There has been much ink spilt and many electrons discomfited arguing what lube does in the barrel. Some argue it lubricates and others that it forms a gas seal. To my mind the paper patch indicates that a barrier between the CB and the barrel is what makes things work.

I too once scorned the concept of PC but I must admit that it has it's place and works.

[Dragonheart]

Blikseme300: you are correct about increasing the diameter can create chambering problems, but a different bullet design can help. We believe you are also correct about the barrier formed by the Polymer Jacket as it is this hard tough jacket the core is riding on, which explains the lack of leading, resistance of the shear force, as well as providing lubrication. Additionally, when the bullets are sized it appears the toughness of the polymer is increased even more.

[NC_JEFF]

Are you noticing any gas cutting at some of these higher velocities on Boolits that may be smaller in diameter than what would be optimal with traditional lube or does PC prevent that.

[Dragonheart]

The smallest diameter we have tested is 30 caliber. It appears that the coating insulates the base of the bullet when the bullets base is coated. So far the highest velocity I have personally fired and recovered a completely intact bullet is 1100 fps and the bullet showed no signs of gas erosion. Another tester was able to retrieve several bullets at 2400 fps and also indicated no gas erosion as the coating on the base was completely intact. When you think about it, the duration of high heat is extremely short at the time of ignition, so the heat transfer is limited. If you melt a PC bullet in your casting pot you see the lead will melt out and the Polymer Jacket remains. We know this polymer can withstand temperatures over 1000 degrees.

[Wardo1974]

I've recovered a bunch of fired bullets up to about 2000 fps velocity with plain bases. Coated with PC, none of them showed any signs of erosion on the base.

If you experience chambering problems from PC buildup - for diameter, get a push-through sizer to squeeze the boolit to the right diameter.

If your boolits are the right diameter but you find they are jamming in the throat, consider shortening your cases. My .38-55 with standard length cases (2.12") won't chamber with PC boolits. But they will when I trim them back to 2.10".

[NC_JEFF]

I wasnt referring to minimum caliber for pcing but I was referring to bullets that may be slightly undersized for caliber (IE...308s in a bore that should have .309s for proper fit) commercial bullets are commonly used and are commonly a little small for what we would consider optimum fit. Would you expect to see gas erosion on the bearing surface of these bullets or do you think PCing would prevent the erosion.

[blikseme300]

Blikseme300: you are correct about increasing the diameter can create chambering problems, but a different bullet design can help. We believe you are also correct about the barrier formed by the Polymer Jacket as it is this hard tough jacket the core is riding on, which explains the lack of leading, resistance of the shear force, as well as providing lubrication. Additionally, when the bullets are sized it appears the toughness of the polymer is increased even more.

I understand and agree that changing to a different mold design would be a solution for a chambering issue but being careful and not over doing the coat thickness works with the 311041 through my Marlins. The nose design and size must be considered when choosing to PC for rifle as nose sizing sounds like a PITA and will probably deform the symmetry of the CB, IMHO, so I don't consider it as a viable method. Being careful and not overdoing the thickness of the coat works for me.

My observation is that PC can be quite thin and still work well, pretty and thick is not important when compared to results as it is just an aesthetic, IMHO. Considering that tumble lubes can work even though they are marginal compared to conventional lube the thin PC coat does not need to have much thickness to be an effective barrier.

Earlier to day I dusted off my Chrony F1 and took it to the range on our the farm along with my 30-30, 308MX and 444S with ammo topped with PC CB's. I typically don't care about velocities as I let the target and primers tell their own story but today I chose to do this.

All shooting was done at 100 yards off the bench using a sand bag for a rest. First up was the 30-30 using the 311041GC over LVR powder with 10 shots which grouped at 2" with an average velocity of 2150fps. Next was the 308MX with the same CB over LVR with a 10 shot group at 2.5" with an average velocity of 2250fps. The kicker, pun intended, was the 444S with a RD 265gn over max case fill (actually compressed) IMR4895. A 1.5" group of 10 shots measuring at 2050fps.

Back at home inspection and cleaning showed powder fouling with no trace of leading which was normal in the past. This PC stuff works. 'Nuff said.

[Dragonheart]

If you are using PC bullets at handgun velocities then a thin coating that covers the bands appears to be sufficient.

But since we are now testing PC bullets at rifle velocities the reason for having a .002" or thicker coating is to add more toughness to the jacket area contacting the barrel. Think of it this way, if you use a copper plated bullet you have a thin copper jacket over a soft lead core engaging the rifling and it is this this thin jacket that is subjected to the shear force created by the pressure driving the bullet down the barrel. The velocity restriction on copper plate is approximately 1250 fps, at greater pressures the thin jacket starts to twist away from the core and flow rearward. You can visually see this on a paper target. When a plated bullet is driven at high velocity the hole in the target will exhibit tears around the hole similar to the teeth on a gear and may also be elongated. This ragged tear is being made by the now deformed copper jacket. The remedy for this problem is a thicker copper jacket, but even thicker copper will fail at some point as the jacket twists away from the core. This is the reason some bullet makers have developed "Core Lock", which keeps the copper jacket locked to the soft inner core.

The Polymer Jacket has a big advantage over copper plate and that is the polymer is tough something copper lacks. It is this bonded tough coating that allows the jacket to resist the shear force. Since standard rifling is .004" in depth, a thicker coating strengthens the jacket. Additionally, sizing the bullet also appears to strengthen the polymer jacket at the contact area.

This is not to say the Polymer Jacket will replace thick copper jacketed bullets, but when you consider you can make your own Polymer Jacketed bullets, that may meet your needs, for a fraction of the cost of premium bullets, I think it's worth some time to give them a try. After all wasn't the the, " Can shoot more for less money" that got you into casting in the first place?

[blikseme300]

One of my rifles I am using as a test-bed for PC'd loads is a Marlin 30-30 using the 311041GC. The published velocity for a 170gn FP commercial jacketed is 2,227fps so I consider my cast 170gn CB's running at a measured 2,150fps average to be moving at rifle velocities. Coating added 0.0015" to the diameters after a single coating. A double coating added too much so that the test rounds would not chamber without force on the lever.

Core-Lokt bullets are not quite equivalent as the cores are probably pure lead and need the copper alloy jacket to keep them from slumping. I have used these factory rounds when hunting and they made a mess when leg or shoulder bones were hit. Not good.

I see the flexibility of the PC as major advantage over gilding as the CB can expand without being constrained by the jacket so even at lower velocities good expansion can occur and dump the energy in the target. All this without having to juggle alloys, lubes and cleaning chores.

[454PB]

I got my Cabine Tree hardness tester today so i decided to play with it a bit. Interesting results. Using range scrap, ingots measured 5.5BHN. Air cooled boolits measured the same. Water dropped measured 11. When PC'd they drop to 7-8 BHN. I tried soaking some pc'd boolits in my convection oven at 430 (as hot as it would get) for 1 hour then water dropped them. They still measured 7-8. I also soaked a water dropped non-pc'd boolit for an hour then water dropped it. It started out at 11 and ended up at 7-8.

Are you letting them "age" before testing?