GUIDE to Bullet Coating
Coating Bullets with Boron Nitride, Tungsten Disulfide, or MOLY
For fans of coated bullets, here is a step-by-step bullet-coating guide. This article explains how to apply dry lubricants to jacketed bullets using two methods. In Part I of this article, Kevin Osborne shows how to coat bullets with a vibratory tumbler. Kevin uses Tungsten Disulfide, but the same procedures work well with Hexagonal Boron Nitride (HBN). (On his WrzWaldo.org website, Kevin sells Tungsten Disulfide (WS2) and he’ll soon offer HBN as well.) In Part II of our article, Larry Medler explains how he applies moly to bullets using a rotary tumbler and NECO equipment.
There are other ways to coat bullets, but both these methods work. The first method is ideal for shooters on a tight budget. Most shooters already own a vibratory tumbler, and the small containers can be obtained for little or no money.
Choice of Coatings
There are three common bullet coatings: Molybdenum Disulfide (Moly), Tungsten Disulfide (WS2 or Danzac), and Hexagonal Boron Nitride (HBN or “White Graphite”). All three products have very low coefficients of friction, and, when applied correctly, all three will do the job. The choice of coating material is up to the shooter. Moly coating is still the most common, but moly can combine with moisture to form harmful chemicals that erode barrels. With moly, you should also wax your bullets, a time-consuming, final procedure not required by the alternatives¹. Tungsten Disulfide is also known as “WS2″, or “Danzac”. (Danzac was a trade name for a Tungsten Disulfide-based product; Danzac is no longer produced, but many people still use this term.) Tungsten Disulfide seems to possess most of the benefits of Moly, but with a higher temp rating. Some people feel WS2 is easier to remove from a barrel than Moly because it does not build up as thickly. Both Moly and WS2 contain sulphur, which can cause corrosion if free sulfides combine with moisture.
Hexagonal Boron Nitride (HBN) is widely used to reduce friction in industrial applications, but it has only recently been adapted to bullets. The “latest and greatest” bullet-coating material, HBN is ultra-slippery, goes on clear (not powdery), and will not combine with moisture or potentially harm barrel steel. HBN also can withstand extremely high temps (1000° C). Many users feel HBN is cleaner to work with than Moly or WS2, and has fewer health risks. David Tubb believes HBN is the best of the three choices, and we predict, with time, HBN will become the preferred dry lubricant for bullet-coating.
|Boron Nitride Source||Molybdenum Disulfide Source||Tungsten Disulfide Source|
¹When moly-coating bullets, we recommend an extra, final step of waxing your bullets. Most experts believe that the performance of Moly is enhanced by applying wax. After extensive, long-term testing, Norma concluded that the combination of moly and wax worked much better than moly alone, at least in reducing friction and barrel wear. NORMA MOLY TEST Results.
To Coat or Not to Coat?
Should you coat your bullets at all? That remains a hotly debated question. We won’t attempt to answer that here. Many shooters, particularly varminters and High Power shooters, believe that application of HBN, WS2, or Moly helps their shooting. High Power shooters are required to shoot long strings of fire with no opportunity to clean. Varminters typically fire a lot of rounds at very high velocities. If coated bullets can reduce copper and powder fouling, that allows a varminter to spend more time hunting and less time cleaning. Some other shooters coat their bullets because they believe this reduces friction and heat in the barrel, which should, theoretically, extend barrel life.
If coating bullets with dry lubricants can reduce friction/heat, extend cleaning intervals and, possibly, make barrels last longer, then why doesn’t everyone shoot coated bullets?
Well, there is no free lunch. By reducing friction, bullet coating has the effect of reducing pressures in your barrel. This means that you’ll get less velocity with coated bullets than naked bullets, given the same powder load. Anti-friction coatings are Speed Robbers. You can expect to lose 20-80 fps after coating your bullets, maybe more with large cartridges and bullets with long bearing surfaces. In order to get back to the velocity you had before coating your bullets, you’ll need to adjust the powder load upwards–perhaps a half-grain or more. That’s not a problem … IF you have extra capacity in your case. If you’ve already maxed out your case capacity, you may need to change powders, or just accept the slower velocity as the “price” of coating your bullets.
WARNING!! Do NOT automatically increase your powder charge after coating your bullets. As with all reloading, start with a KNOWN SAFE MODERATE LOAD for naked (un-coated) bullets of the same type/weight and work up in small increments, checking for pressure.
The basic mechanism of moly coating bullets is impact plating, a process by which the coating is physically (impact) applied to the bullet at a molecular level. Over the course of coating bullets for 12 years using the NECO process and materials, I’ve developed a few techniques to produce bullets that have a “factory coated” look.
1. Start with Clean Bullets. This is simple enough, but some people overlook it and others overdo it. Get the bullets out of the box, wash them with warm water and dish soap and dry them. No need for harsh chemicals, after all, we’re only removing some surface dirt from shipping and maybe some left over lanolin from the forming process. Don’t handle them with bare hands once they’re clean, your skin oils will contaminate them.
2. Get Everything Hot — Real Hot. This is probably the single most important element in producing good-looking moly-coated bullets. I put the tumbler, the drum and the bullets out in the sun for at least 30 minutes before starting and then do all the tumbling in direct sunlight. On a summer day in Arizona, everything gets to the point that its uncomfortably hot to handle. If you are tumbling in the winter, you should heat the bullets in some form, a hair dryer can be useful, but they will cool off in the drum if you’re tumbling in cold temperatures. Your best bet is to plan ahead and do your coating in the summer. I coated about 3000 bullets in a couple of days recently to see me through our winter season (we’re a bit reversed from the rest of the country in terms of shooting season).
3. Polish the Bullets. When the moly coating is done, separate the bullets from the shot and roll the bullets in a towel to give them a light polish. I keep one towel for this purpose and it’s very moly impregnated; it looks nasty and works great. I use a Radio Shack video tape eraser (a big electro-magnet) to separate the shot from the bullets, quick, cheap and easy.
4. Don’t Skip the WAX. The bullets only need to go in the wax drum for one to two minutes, it goes on very quickly. Go very light on your wax or it will clump on the bullets. After the wax drum, roll the bullets in the moly towel again.
If you did all of these things and the temperature was hot enough, you should end up with coated bullets that look like they were made that way — with a perfectly smooth finish.
|Part One — How to Coat Bullets with WS2 or Boron Nitride|
by Kevin Osborne, WrzWaldo.org, coatedbullets[at]wrzwaldo.org
In this section, I’ll show how I coat my bullets with Tungsten Disulfide (WS2). You can follow the same procedure if you prefer using Hexagonal Boron Nitride (HBN). Step by step, you’ll see a batch of 34gr, 20-caliber Dogtown bullets being coated, start to finish. Here they are fresh out of the box:
STEP ONE: Organize Gear and Components
I use a standard, inexpensive vibratory tumbler. My unit is a Frankford Arsenal Quick-N-EZ. I use two sizes of pill bottles. The shorter bottles will hold one hundred 20-caliber bullets and the larger will accomodate 200 bullets. NOTE: These quantities are for small, 20-caliber bullets. The capacity would be less for larger calibers. [Editor's NOTE: It's wise to quickly clean your bullets at the start of this process. Plain dish-soap and water works fine.]
STEP TWO: Add Pellets
You need some metal pellets to impact-plate the dry lubricant on to your bullets. For burnishing media I use standard .177 BBs. Any brand will work (but see comment below). With the small bottles I put 3/8″ worth of BBs in the base of the bottle. The larger bottles get a 1/2″ layer. [Editor's NOTE: While Kevin is correct that almost any small metal balls will work as impact media, uniform steel balls probably work best. Consider also that steel shot can be separated from the bullets with a large magnet. NECO developed and patented the method of applying dry lubricant to bullets via impact plating, and the use of steel balls is part of NECO's patented process. You can obtain steel impact media and other coating supplies from Neconos.com.]
Here are one hundred (100) 34gr Dogtown bullets in the small bottle.
STEP THREE: Add Dry Lube Powder
After adding bullets and BBs, drop in the lubricant. NOTE: With fresh burnishing media (BBs) you need to put in extra WS2 because you will be coating the BBs as well as the bullets! Shown below is about 8 grains of WS2. This will normally coat about four hundred (400) 39gr Sierra Blitzkings. Just dump it on top of the bullets, close the bottle, give it a few shakes by hand for good luck, then drop it in the tumbler.
STEP FOUR: Tumble Containers
You will want to tumble your bullets for at least 30 minutes. To verify if your bottles are rotating (like the drum in a clothes dryer), leave the tops of the pill bottles exposed in the bowl so you can see them spin. NOTE: Some folks will tumble their brass at the same time. I have gone away from tumbling brass while coating bullets as I think it was interfering with the rotation of the bottles. [Editor's NOTE: Some shooters like to tumble for as long as 3 hours. The correct time will depend on your tumbler and the type of bullets. As German Salazar explains above, getting everything very hot will give you better results in a shorter time.]
Here is what they should look like after 30 minutes in the tumbler. Notice how the bullets and impact media (BBs) are well mixed! This is important for good, even coating.
STEP FIVE: Inspect Your Bullets
Pull one coated bullet from your tumble bottle and polish the bullet by hand. If it is coated to your liking, you can polish the rest of them. If the sample is not coated evenly, switch on the machine and tumble the bullets some more.
STEP SIX: Move to Polish Container and Shake
I use a RubberMaid-style container for the first polish. This will be bigger than your tumbling bottle. Line the container with paper towels and fill with bullets from your tumbling bottle. To cut down on the mess and to not waste WS2, I pull them from the bottles with a pair of tweezers. This keeps your hands clean. If you have access to a paper shredder, shred some newspaper and put it in with the bullets. If you don’t have a shredder, just use the paper towel. Put the lid on and shake the bullets for about 30 seconds.
Here is what they should look like after approximately 30 seconds of shaking, with shredded newspaper in the container.
Here is how they will look after the first polish. At this point you could call it good, but you will end up with black hands after reloading. (This is not a problem
if you use gloves).
STEP SEVEN: Final Polish
I like to give the bullets one final, manual polish. You will need to get an FPD (Final Polish Device). Here is a picture of my FPD–an old sock. I simply put the coated bullets in the sock and shake for another 30 seconds or so. Shown below is the end result–nice, evenly-coated bullets.
Forum member Mike Creek offers some additional tips that should help you get superior results with Tungsten Disulfide: “I’ve used the tumbling method with WS2 for over 10 years. The system works well. There are three enhancements to the process I recommend:
1. Clean the bullets before coating with acetone/soap and water.
The Final Result–Coated Bullets
The entire process of bullet coating with WS2 can be accomplished in an hour or less. It can take more time if you clean your bullets (and if you coat with Moly, add time for a final waxing). To date the only bullets I have cleaned were some old tarnished hollow points for my 264 Magnum. All new bullets I do go right in from the box. However, I know other shooters prefer to clean their bullets first. [Editor's NOTE: If your "raw" bullets have lube residue or other contaminants on the surface, you should clean your bullets first. This can be done with soap and water, a Simple Green solution, or other mild cleaners. Do NOT use ammonia-based cleaners or bore solvents--they can strip copper off the jackets.] Below are “Before” and “After” images showing the coating process with 35gr Berger bullets.
|Part Two — Moly-Coating Bullets with NECO System|
Rifle Silhouette Shooting,
By Larry Medler
Moly-coating of bullets is controversial. Many folks believe moly reduces fouling, and prolongs barrel life. Others argue it really doesn’t help much, if you start with a good barrel. I’ll just say I prefer to shoot moly bullets in many of my guns. Using moly lets me fire more rounds between cleanings without losing accuracy. I also think barrel life can be extended by using moly-coated bullets. Apparently Norma agrees. Norma Moly Tests.
Heart of the System — Thumler’s Rotary Tumbler
I already had a Thumler’s Tumbler so it seemed logical to use it for this project. Two 40-ounce Peanut Butter (PB) Jars fit perfectly inside the unit. The plastic jars in the Thumler’s Tumbler are my answer to controlling moly mess. One jar is for cleaning the bullets (left jar) and the second jar is for the moly coating process (right jar). The extra jar in the center is to show the Jar’s perfect fit in the tumbler drum.
My NECO Moly Kit (from Neconos.com) came with three bottles of steel shot. For this project, I used one entire bottle of shot in a cleaned, clear plastic 40-ounce PB jar. I placed the jar in the Thumler’s Tumbler and watched the steel shot in action. The steel shot appeared to have a nice rolling and sliding action as the jar turned end over end in the tumbler.
I add a small amount of MidwayUSA Brass Polish to the corncob. This really makes the bullets shine. I use a simple sand-box toy to separate the bullets from the corncob media.
NOTE: Moly Dust is not a good thing for your lungs. It’s not a bad idea to use a paper mask.
My current process is to tumble for three (3) hours using between 5 to 6.5 grains of moly per batch of bullets. In a batch, I run either fifty 30-caliber bullets, or one hundred 22-caliber bullets.
So far I have coated over 8500 bullets in 134 batches. The Moly PB Jar has been tumbled 400+ hours with the steel shot. It still looks and feels as good as new.
NECO Sieve Set
Finished Moly-Coated Bullets
Overall, by using the PB jars inside the Thumler’s Tumbler, this is not a messy process. And the Thumler’s Tumbler is very quiet with the lid on–the rubber drum liner dampens noise very well. For convenience, get a 24-hour programmable appliance timer. Look for a timer that can turn the Tumbler off after a pre-set period. But make sure it won’t turn the machine back on again the next day!
To conclude, for those of you moly fans, if you have a Thumler’s Tumbler go for it.
If you prefer a different brand of bullet, or want bullets coated with Tungsten Disulfide or HBN (as opposed to Moly) there are services that will coat your bullets for a fee.
NECO offers moly-coating for large quantities of bullets. Prices are based on bullet weight. The minimum fee is $15.00 for 3.5 lbs of bullets, the equivalent of 245 hundred-grain bullets. Bulk Rates: $21.75 for 7 lbs, $28.50 for 10.5 lbs., $35.25 for 14.0 lbs., $41.25 for 17.5 lbs. and $6.00 for each additional 3.5-lb batch. At this time, NECO does NOT offer WS2 or HBN. Call Neconos for more information.
Superior Shooting Systems (David Tubb) pioneered the use of Boron Nitride on David Tubb’s DTAC-brand bullets. Superior Shooting Systems will also apply Boron Nitride to other manufacturers’ bullets. The cost for the HBN coating service is $0.05 per bullet with a 1000-bullet minimum order($50.00/1000 bullet run). The fee is the same for small bullets and large bullets. The following guidelines apply: “SSS Inc. can combine a customer’s bullets into a single batch in order to make the 1000 bullet minimum. SSS Inc. suggests that the customer pick dissimilar bullets if they are to be mixed. All bullets received by SSS Inc. for Boron Nitride coating will need to have been thoroughly cleaned in new tumbling media prior to shipping to SSS Inc. Factory-sealed boxes of Sierra or Berger bullets do not need to be cleaned prior to coating.”
Topics: Friction, Bullet, Anti-Friction, Moly, Molybdenum, Disulfide, Danzac, Tungsten, WS2, Boron, Boron Nitride, Hexagonal BN, Hexagonal Boron Nitride, coated bullets, friction coating, Tumbler, Tumbling, DTAC, David Tubb, WRZWaldo, Kevin Osborne, Larry Medler, German Salazar, speed, coating, cleaning interval, reduced heat, NECO, neconos.com, NECO System.
Contents Copyright © 2009 Kevin Osborne, Larry Medler, and Accurateshooter.com | 6mmBR.com, All Rights Reserved. No reproduction, in whole or part, without advance approval in writing.