Is HBN worth it?

[Heman]

Shawn,
I think I found your problem.
I'm reasonably sure that you are supposed to coat the bullets, not yourself!! LOL.

Lloyd

Lloyd,
That very well may have been the issue always wondered why people looked at me weird when showing up to matches with all this white powder on me..... I remember you put me on to it, I used it, but when I was adjusting the seating depth on 142's in my 260 it started deforming noses and I figured out the issue. Needless to say I quit using it and I've shot ok since then.

I surmise the reduction in copper fouling is for the same reasons I stated, its an abrasive so its scratching it out for you.

 

[69mach]

I started using the wet method with Molly back when Whidden did my first .243 barrel. Only reason I did was the .243 obviously works very well for him, he said it is a system so I followed everything in his system. Now along with the .243 I was bored so I molly'd every other cartridge I shot (.223, .260, .280, and .308). I still shoot Molly, the water method is easy to do and I do a bunch up at the time. Barrel life is excellent but then I also use cool powders. The only cartrdige I don't molly anymore is the .223 as I wasn't getting the velocity in the palma gun that I wanted and anything above 25gr of Varget/N140 was a PITA to load. Now that I'm shooting N135 I thought about trying it again as there is plenty of case room. Do I really need to molly the others no, they aren't going the 3,300fps the 243 is, but I still do as I don't notice the copper fouling as quickly as I do when naked.

The difference between molly and HBN was when you compare it to a naked bullet the velocity with molly goes down but with HBN it went up. So right there tells me HBN increases pressure or at least it was how I was applying it (NECO method with shot). The other comparison is on .243 barrels. The .243 was originally barreled with a HART barrel (Dad's decision and I inherited the rifle) with 107SMKs HBN coated and IMR4530 by 900+ rounds I couldn't touch the lands anymore. I'm on my 3rd .243 barrel since going to N160 and Molly. Now N160 is WAY cooler but I get around 2,500 rounds per barrel and the second barrel is at 2,624 and last match it shot a 200-12x at 1000 but I pulled it cause I knew it was close. Need to put it back on and see when it goes. Now part of the round difference was n160 as IMR4350 is a freaking blowtorch, but also a lot was the HBN being an abrasive it just ate away at the lead in the chamber.

i have had different results than you. i shoot a lot of 115 dtacs and with the same load of 4831sc the hbn coated bullets are always slower. this remains consistent in both my 22” and 28” 6xc chambered barrels.

 

[mikecr]

So what would cause lower MV with HBN?
HBN friction CoEff is .15 to .70
Consensus on MoS2 seems .15 or slightly less
WS2 is .03 to .07 (about the slipperiest stuff there is).

WS2 does not affect MV.
MoS2 affects MV only because of it's latent heat of vaporization(it's also lowest in temp stability).
So HBN has higher friction than other dry lubes, but it's better than uncoated friction, and HBN is highest in temp stability.
I can't think of a reason that MV would change with HBN.

 

[Woofie]

I have been using HBN as a bullet coating for several years now. I started out after reading David Tubb's comments on it. While I happen to think, kindly, that Mr. Tubb is as good a marketer as he is a shot, I have not been unhappy with the results. Latterly, I have been buying the the 0.5 micron size HBN powder from bulletcoatings.com.
I previously used factory moly bullets from Speer and Sierra. I have given my shooting buddy permission to shoot me if I am ever so stupid as to use them again. I measure the time it took to get the accumulated moly out my rifles' throats in days, not hours. I would sooner poke myself in the eye with a knitting needle than use moly again.
That said... I am not an industrial chemist or engineer but understand that HBN (hexagonal borion nitride) is a ceramic compound that forms flat layers, is very tough, and has good tribology, esp. with other HBN coated surfaces. It is also very resistant to high temperatures. I also use it as a neck lube for my neck sizing mandrels figuring HBN:HBN will give me the most consistent neck tension. Who knows if I am correct, but it seems a reasonable hypothesis.
I find it improves time to cleaning, esp. from metal fouling, which in my case is important because I shoot Savage rifles with their typical rough internal finish, It also seems to reduce pressures but since I don't own a Pressure Trace I can't testify for sure.
I do coat bores after cleaning with an emulsion of HBN in IPA (industrial alcohol, not beer :-> ). This saves the transfer time otherwise required from my coated bullets of 10-20 shots (est.).
I do not believe HBN is hygroscopic, but because of its fine grind, it will clump in a damp atmosphere.
I believe HBN is becoming more used generally. For example, I'm 99.9% sure STP is using it in their new ceramic oil additive. Probably a nano grind (a billionth of a meter -- a micron is a millionth of a meter) to pass filters with no issues.
On the nano grind: I am sure it would be a better bullet and barrel coating choice but after reading the handling cautions on bulletcoatings.com I have decided to give it a pass. If I could buy it in a solution I might give it a try, esp. as a barrel coating. Mixed with Kroil I suppose it would really penetrate the internals of a barrel about as well as anything.
Just my 10c as a happy HBN user.