My HBN experience and process

[Mikecr]

Some of the HBN claims seem wrong.
For instance, the friction coefficient of HBN is 0.23 in dry air,, for WS2 it's 0.03 (incredibly slippery, not even a close comparison).
WS2 does NOT change muzzle velocity. This, countering everything imagined out there about friction affecting MV.

The only way MV would change with HBN is if it flashed off like MOLY, and exhibiting latent heat of vaporization, as MOLY does.
But HBN is declared as immune to burning off.

I also wonder if HBN is in any way like the fouling our bores need for cold bore accuracy.
I know that WS2 pre-fouled bores function as though treated with a universal fouling. The WS2 1st cold shot actually is with all cold shots to follow. Maybe HBN also just happens to be this way, but it would surprise me that a material so different would function the same in this regard.

Also, does HBN build up in bores (like MOLY), or does it clean right out (like WS2)?

 

[QuietTexan]

I also wonder if HBN is in any way like the fouling our bores need for cold bore accuracy.
I know that WS2 pre-fouled bores function as though treated with a universal fouling. The WS2 1st cold shot actually is with all cold shots to follow.

I would doubt it does anything for cold bore, sounds to me more like there's a reaction in the surface metal of the barrel and the result reduces galling damage somewhat IF the particle size is fine enough to get inside the surface profile of the metal before the heat/pressure is applied. Maybe it works better in a limited Ra range, and efficacy is reduced if the profile is smoother.

I still use WS2 (on your recommendation) to pre-foul clean barrels and it works great.

 

[Pdvdh]

HBN does, absolutely cause a change in MV. Got no idea why WS2 doesn't change velocity.

HBN is believed reduce bore to bullet friction. Reduced friction would reduce pressure. Reduced pressure reduces MV. These cause and effect relationships are all logical. Comport with the physics of friction, pressure required to generate the force to overcome friction, and consequential bullet velocity.

Higher MVs become possible after HBN treatment by using a higher powder charge to re-establish pressures that were used prior to HBN treatment. Higher, safe powder charges are possible because of the reduced bullet to bore friction.

If WS2 doesn't affect MV, then it must not be changing the coefficient of friction between the bullet and the bore. Unless you have a better explanation on the physics in-play with WS2.

 

[Window]

I can imagine lol. I'm surprised you've stuck with it this long lol. Nice work.

Dangit Calvin, any idea what causes that?!?

 

[Calvin45]

Very nice write up, impressed with how you set out the process.
As you know, I've been doing this too for a good while and got my newer info from David Tubb too. My process is a little different, still use heat, but when I started I was under coating and not using steel balls, I still use ceramic balls, but I tumble twice. I run the HBN into the barrel with Shellite (Mineral Spirits) because it is the fastest evaporites you can buy and cleans extremely well.
I haven't tried it on any pure copper bullets, interesting it coats them so well, it works exceptionally well on pure brass bullets, and ABLR bullets really like it as does Berger, Nosler CC and RDF respond well to the coating. I know I won't be going back to bare bullets when I start comp shooting again.

Cheers.

I'll have to look into that shellite mineral spirits product for sure. Always after a better mousetrap. Thanks for the tip

 

[Calvin45]

Dangit Calvin, any idea what causes that?!?

You mean the kids?

We've had a number of people ask us haha.

 

[1mechanic]

You mean the kids?

We've had a number of people ask us haha.

Instead of coating the bore you ever thought about wrapping the barrel. lol

 

[Calvin45]

Some of the HBN claims seem wrong.
For instance, the friction coefficient of HBN is 0.23 in dry air,, for WS2 it's 0.03 (incredibly slippery, not even a close comparison).
WS2 does NOT change muzzle velocity. This, countering everything imagined out there about friction affecting MV.

The only way MV would change with HBN is if it flashed off like MOLY, and exhibiting latent heat of vaporization, as MOLY does.
But HBN is declared as immune to burning off.

I also wonder if HBN is in any way like the fouling our bores need for cold bore accuracy.
I know that WS2 pre-fouled bores function as though treated with a universal fouling. The WS2 1st cold shot actually is with all cold shots to follow. Maybe HBN also just happens to be this way, but it would surprise me that a material so different would function the same in this regard.

Also, does HBN build up in bores (like MOLY), or does it clean right out (like WS2)?

For my part I don't know the answers to your questions and certainly don't have a true scientific method of inquiry nor the equipment needed to test some of this.

I simply cannot deny my real world experience regardless of what numbers or data points might suggest is and isn't possible.

As far as cleaning…I think it's neither like ws2 nor moly. It certainly does NOT accumulate and clump up like moly can. I also don't know that it cleans right out like ws2. It does seem to actually impregnate the bore irreversibly, but beyond that doesn't seem to build up in any way I've noticed.

 

[Old Rooster]

Some of the HBN claims seem wrong.
For instance, the friction coefficient of HBN is 0.23 in dry air,, for WS2 it's 0.03 (incredibly slippery, not even a close comparison).
WS2 does NOT change muzzle velocity. This, countering everything imagined out there about friction affecting MV.

The only way MV would change with HBN is if it flashed off like MOLY, and exhibiting latent heat of vaporization, as MOLY does.
But HBN is declared as immune to burning off.

I also wonder if HBN is in any way like the fouling our bores need for cold bore accuracy.
I know that WS2 pre-fouled bores function as though treated with a universal fouling. The WS2 1st cold shot actually is with all cold shots to follow. Maybe HBN also just happens to be this way, but it would surprise me that a material so different would function the same in this regard.

Also, does HBN build up in bores (like MOLY), or does it clean right out (like WS2)?

I mentioned I had a container of WS2 and I cannot find it.
If possible could you give me the name of the seller where I can buy WS2?Ungraded China WS2 is all over the market and the graded stuff is a bit higher but worth it to know you have the real stuff.Been too long for me to remember.

 

[Calvin45]

I mentioned I had a container of WS2 and I cannot find it.
If possible could you give me the name of the seller where I can buy WS2?Been too long for me to remember.

It's tungsten disulphide, and I believe the first product marketing it as a bullet coating was called DANZAC. don't know if they're still around.

 

[Window]

You mean the kids?

We've had a number of people ask us haha.

That's awesome! Love them all like there's no tomorrow. We only have three, but if it were up to me, we'd have ten.

 

[Old Rooster]

Someone a few years ago someone here gave me the name of a seller and I bought a container.I used some on my boat trailer wheel bearings and it worked so well I gave the container to someone who packed his wheel bearing and I still had well over 1/2 of the container left.If I could find it I would still have enough to last a couple of years or longer but can't find it.Need to buy another container and keep it in reloading room.

 

[Calvin45]

@Mikecr I've been doing some more research as your questions are good ones and I'm curious about the possible answers as well.

First off, I didn't know that ws2 doesn't change velocity. There is zero doubt that hbn does, I've observed this, as does the Winchester/Nosler black copper oxide lubalox
Coating, as does moly. That's just weird. But very interesting.

One thing of note…ws2 is as you say much slipperier… at room temp in air. I have reason to believe this isn't the case in the environment of a rifle bore. Neither ws2 nor hbn melt per se but they do sublimate and dissociate at certain temps. Ws2 isn't even remotely as thermally stable as HBN. It "melts" or gasses off at 1250 celcius. HBN only does this at 2970 Celsius. So there's that.

Additionally in studies regarding oxidation temps of 2 dimensional layers of ws2 and hbn, the ws2 begins to oxidize in air very rapidly at any temperature over 350 celcius. Ws2 is slipperier than hbn…I don't know if wo3 is!

Hbn resists oxidation in air at temperatures up to 1200 (at that point the ws2 is far past oxidation and getting into sublimation and dissociation territory).

So I don't think it's any mystery at all now. Ws2 is, in fact, not even remotely comparable to HBN regarding both chemical and thermal stability.

 

[QuietTexan]

HBN is believed reduce bore to bullet friction. Reduced friction would reduce pressure. Reduced pressure reduces MV.

I get where you're going here and I agree with the general direction. But I'm not sure the last part is worded precisely enough to say I agree fully.

In this instance there would be a reduction in PEAK chamber pressure, but the result is a flattened curve and not a decrease in total amount of gas expansion if the mass of propellant is constant. Figuring the integral of each pressure curve might be a shortcut to confirm, but the total amount of work done by a fixed mass of propellant in the same sized pressure vessel should be the same even with a lower peak pressure. So yes PEAK pressure is reduced but that doesn't translate to loss of velocity. That can be proved with AI cartridges netting same velocities with essentially same charge weights at lower peak chamber pressures. AIs would require a very small amount of additional propellant mass to make up for the increase in volume of the chamber, but chamber dimensions don't change with HBN treatment to that doesn't apply here.

Work is Force x Displacement (barrel length is constant), and Force is Mass (bullet weight is constant) X Acceleration, so work should vary directly with acceleration since the other two values are constants in our case.

If HBN reduces friction it should result in something between faster acceleration and same acceleration with less friction, aka heat loss to the metal barrel. The amount of work done in a coated bore either increases, or at most doesn't change. I don't see a case where the amount of work decreases, netting a lower velocity at a constant charge weight. Work would increase if there's higher acceleration and/or less heat loss, or not change if increased acceleration results in increased parasitic loss relative to the baseline and they cancel each other out. But less friction, same acceleration, same amount of gas volume (or ideally less friction, more acceleration, same gas volume) should result in higher total work .

A shorter way to look at this might be that since heat loss from friction is a loss to outside the system, any reduction in friction effectively results in less parasitic loss, thus a higher total energy budget in the system even with the same propellant mass.

Admittedly what I said is not accounting for decrease in propellent burn velocity at lower pressure, I'm making the assumption the same amount of propellant mass is converted to gas in both case. This should be an accurate assumption in a high-power centerfire case, but would not be in a low-pressure case like 458 SOCOM where the bore volume is a significant enough factor to affect the completeness of powder burn pretty drastically. I've seen it in 300 BLK subs because of small case capacity/charge weight relative to bore size. But high-pressure cartridges should have a relatively consistent burn completeness percentage in the top 1/3rd of the pressure range.

Higher MVs become possible after HBN treatment by using a higher powder charge to re-establish pressures that were used prior to HBN treatment. Higher, safe powder charges are possible because of the reduced bullet to bore friction.

This I do agree with, and is also part of the logic behind Shawn Carlock's +P throat design. Reducing peak chamber pressure allows you to run more propellant to get back to the same peak pressure, netting a higher average pressure compared to the original throat design. That logic should be the same for a HBN treated bore.