November 9th, 2008

Applying Boron Nitride (HBN) to Bullets

hexagonal boron nitride bullet coatingIn our recent article on Bullet Coating we covered the basic principles of applying dry lubricants to “naked” bullets. This article covered the three main coating options: Molybdenum Disulfide (Moly), Tungsten Disulfide (WS2 or “Danzac”), and Hexagonal Boron Nitride (HBN or “White Graphite”). All three compounds can be impact-plated on to bullets with relative ease, using inexpensive equipment. Moly is still the most popular choice, but many more shooters are considering HBN because it is ultra-slippery, it is less messy, and it offers some advantages over Moly or WS2.

After we published our Bullet Coating feature, many readers asked for more info on HBN. Some current moly users had questions about switching over to Boron Nitride. Recently Forum member Larry Medler published an excellent web article discussing the process of applying 70nm HBN using plastic jars and a Thumler’s rotary tumbler. If you are working with HBN currently, or plan to experiment with Boron Nitride, you should read Medler’s HBN-Coating Article.

After coating some bullets for his 6XC, Medler seems “sold” on the merits of HBN. Larry writes: “The coating process is much better than Moly — no black mess. My coating process times are the same as for Moly. Three hours of tumbling in the corn cob and three hours of tumbling in the steel balls with 3.0 grains of hBN Powder. The bullets look something like sugar-coated donuts when I dump the jar of steel balls with the freshly coated bullets into my sieve to separate. The coated bullets wipe clean to the touch with a little towel rub down and remain very slippery. So far I am very pleased with my coated bullets’ smoothness and appearance.”

hexagonal boron nitride bullet coating

Field Tests Are Very Promising
Interestingly, Larry’s HBN-coated bullets are shooting flatter, with tighter vertical, than his moly-coated bullets. Since he has also pointed the tips of this batch of bullets, it’s not clear whether the reduced drop is due to the pointing or the HBN coating, but the results are certainly encouraging: “I have shot the HBN-coated bullets a couple of times now at 600 yards and everything seems to be okay or a lot like Moly. Funny thing is the HBN-coated bullets are shooting higher by 7/8 MOA. I have to check the speed and see if it has changed enough for that POI change. Good news is I had a string of 15 shots with less than 1.5 inches of vertical which is the best I have ever seen with my rifles. Is that due to the hBN or bullet pointing?”

Boron Nitride 500gr Packs Available for $20.00
Larry acquired more HBN than he needs, so he is offering smaller quantities for other reloaders to try. Larry tells us: “If anyone would like to try using the 70 nm Hex Boron Nitride powder, I have made a few small bags with 500 grains of the HBN powder. That’s enough to coat 10,000 -16,000 bullets based on my results so far.” $20.00 includes shipping. Send email to anyrange [at] to order or to check availability.

Photos courtesy Larry Medler, All Rights Reserved

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