Moly Coating Question

[bootlaceb]

I read with great interest the articles on dry lube treating your bullets. I have 2 questions;
1-Why and how do you apply the wax to the bullets,
2-Do you have to do the same to Tungsten Disulfate treated bullets, and why/ why not?

 

[spclark]

Waxing is accomplished in much the same way as the lube-coating step but doing it correctly can be tricky. The why part of your questions is harder to answer. The folks who developed the moly-coating process determined the results are more consistent when the wax step is included. Why that is I've never heard explained well.

Many folks who "roll their own" don't bother with the wax & say they don't see the difference. Commercial moly-coated bullets all will have the wax applied.

Considering that both moly and tungsten bullet lubes contain sulphur, the wax might help resist the effects of humidity reacting with whatever free sulphur may be present,minute quantities but still possible) to form corrosive acids over time.

David Tubb recently discontinued coating bullets with moly in favor of a high-temp industrial powder lube called boron nitride. If he felt need of change I'd think it'd be for a good reason. He no longer sells moly-coated bullets, having gone to the BN lube 100%.

http://www.davidtubb.com/tcom_images/dtac/dtac_bn_coating.html

 

[CPorter]

The main reason I've heard for the wax coating was to prevent the coating from rubbing off on your hands. Both Moly and Tungsten Disulphide make a real mess; something you don't want in a commercial product.

The free sulphur as mentioned and the combustion products of moly,tungsten has a higher temp rating) can form sulphurous / sulphuric acids in the presence of moisture. That's why is very important to run a patch with oil or bore cleaners down the barrel ASAP when finished firing or before putting the gun in the case. Tungsten is better than moly and it may be that boron nitride will be better the tungsten.

In doing my own I never used wax with moly, tungsten or boron nitride. Some of it rubs off and gets on your hands when handling the bullets. I've been told a different technique might work better. A tumbler is supposed to work better than a vibrator.

 

[GermanS1]

Norma conducted very extensive tests of the moly-coating process prior to adopting it for their target ammunition. They found, over the course of tens of thousands of shots in a lot of barrels, that the wax accounted for about 30% of the total friction reducing effect.

NECO's patents include the wax, Norma's tests back that up. I don't have the time, budget or inclination to rerun all their testing, so I do what I believe to be logical - apply the wax. It's already in the kit, it takes 1.5 minutes of tumbling time and another 2 minutes to separate the bullets from the shot. So, for 3 minutes of effort, I complete the process and remove all doubt. Others have a different approach, I'm just laying out my reasoning.

 

[GermanS1]

Donovan, that's what I do also - clean at the end of the day. I clean with Shooters Choice and IOSSO, no brushes. The borescope shown me that the barrel is clean at the end of the process. The first shot at 500 or 600 yards is usually about 1 moa low, the second shot is right on for elevation.

 

[GermanS1]

I dug deep into the computer and found the Norma report, so here it is:

MOLY
Latley there has been a lot of discussions about moly. After Kevin Thomas article in PS Jan we have received quite a few e-mails. Since we have been coating bullets for a few years we would like to share our experience. I guess this article will solve a few questions but probably raise a few too.

Briefly we have found that molycoated bullets do:

- decrease pressure by 3-5% depending on cartridge, bullet and powder
- decrease velocity with 0,5-1,5% - reduce metalfouling
- increase accuracy under certain circumstances
- very likely increase barrellife

During testing we have also observed that first shot out of a cleaned barrel is within the following group,@ 300 m).

Moly is a superb friction reducer and it’s bearing capacity is beyond the yield point of known metals. When a molycoated bullet enters the throat and travels down the barrel it has less friction than a ordinary bullet. So it is not surprising to see a lower pressure. We have not done any huge tests with many calibers but these 3-5% has been there every time.

If pressure is reduced velocity will also be lower with the same charge. The interesting thing is that velocity is not reduced as much as pressure. Thus, by increasing the charge you can usually get 1-2% higher velocity with moly bullets.

Metal fouling is hard to measure accurately. We have observed through bore scopes and compared need of cleaning. It seems as coated bullets gives a certain degree of fouling but it more or less stays there. Our subjective estimation would be 30-40% less metal fouling and much slower buildup. This depends on cartridge, pressure, powder and bullet. I’m pretty sure we will see improvement in this area on the powder side quite soon.

During our initial testing of moly we fired some 140 gn 6,5 bullets for accuracy. These bullets look very much like Sierra’s # 1740. We could see no improvement in accuracy at all. Testing continued with 6 PPC and Sierra 107 gn MK. About 60 5-shot groups were fired indoors at 100 m with three different loads. Every load showed smaller groups on the average,6-11%) and less standard deviation with moly. That was just a hint, no significant improvement,usually significance on 95% level is accepted as true). We went back and retested the 6,5 bullets with two different powders. Same result as first time – nothing happened. Then we coated our 130 gn VLD,Bill Davis design) bullet and fired a substantial number. Significant improvement on 95% level!

Later we were going to load this 130 gn VLD bullet with MRP. Quality of the bullets was ok from the continuos testing during production but the results were quite bad for the loaded cartridge. Every single item in the cartridge was changed one at a time. When two different cases were tested things happened with one of them. That batch of cases was old and had thick necks. Suddenly accuracy was back. Also variation in pressure, barrel time and velocity was app. cut in half. Neck tension or extraction force as we call it, was the answer. We went back to the present cases and used a slightly faster powder and it worked fine. The 140 gn was tested once again but no responce in accuracy.
So, be careful when using slow powders and moly coated bullets – it is very important the powder charge starts to burn the same way each time. One thing that differ from our testing and some others is that we always use new cases because that is the way loaded ammo is produced,jealous eh?). Sized cases would not be the same. Typically moly takes down the extraction force with 50%.
One explanation of the increased accuracy could be that moly helps the bullet align in the bore. Thus, bullets with long bearing surfaces would not gain much from that help. Pistol bullets in 9 mm has been coated with no effect on accuracy. Probably more factors are involved that we don’t know of at this time.

When it comes to increased barrellife statistics start to get a pain in b- - t. It is too much a work with too many variabels to do enough tests. However, we took a new Sauer 6,5 x 55 barrel and fired it 10.000 rounds with our standard load – 130 gn at 2700 fps. It was examined with a borescope every 1.000 round + measured with gauges. After 5.000 it looked very nice but after that it started to show pressure cracks. Wear in boredimensions was more or less normal. At 10.000 rounds it was set up at 300 m outdoors in a machinerest and 10 x 10 rounds were fired. It might have been a good batch for this barrel as average group size was 71 mm c to c or less than one MOA. That was good enough for us not to worry about barrellife.

A shortcut to prove less barrelwear was to find out whether temperature of the barrel was lower with moly bullets. A heat sensitive digital camera was set up and we fired conventional bullets and moly coated bullets at the same muzzle velocity from a conventional target rifle. Of course the barrel was fired with uncoated bullets first and then cleaned. First thing was then to shoot some moly bullets to break in the barrel. It was also allowed to cool down to same temperature each time. Shooting pace was controlled etc. There was no difference in temperature at all. If it had been, it would more or less has proven less wear. David Tubb told me he had heard pistol shooters could feel the difference from moly bullets so there might be things out there!
Some of our people who meet a lot of target shooters usually bring a borescope with a monitor to the major competitions. They look through hundreds of barrels each time. Their strong belief is that moly helps to prolong the accurate life of the barrels.

A few tests were made to find out if the wax was necessary and if thickness had any influence. This was only tested with respect to pressure and velocity, no accuracy testing. Moly alone seem to give 60-65% of full effect. Wax only didn’t matter much. Moly together with wax made a better job. To have some excess wax didn’t hurt but too little made the reduction in pressure / velocity less. Only 6,5 x 55 was tested.

Yesterday we compared our normal wax coating with a thinner and much nicer looking coat. There was an increase in velocity with 0,19% and in pressure with 1,23% when using less wax. No drop in accuracy was noticed.

Our powder supplier – Bofors – ran a few tests with both moly and wax to find out if there were any negative effects on the powder. Moly destroyed the stability of the powder but only when concentration was a few hundred times higher than what normally occurs. Carnuba wax was neutral.

Better trajectory with moly?
We have done exactly the same tests as Kevin and usually we have seen a small decrease in BC. Probably due to our relatively thick wax coating. The first test we made showed an increase in BC of app. 3% but it was due to a mix of bullet batches. Also Randolph Constantine mentioned in PS Aug 98 that we found better BC using a doppler radar. I’m sorry but that was a misunderstanding. What we found was that BC was more or less the same from 200 m out to 600 m with conventional bullets. We didn’t know about moly at that time. Some good shooters report on higher impact with moly but I guess that must come from shifted barrel vibrations or different barrel time. I’ll be back on that later as we will test it in a 6,5-284 when we have the brass – May.

A good friend won a 500 box of our 6,5 Diamond Line ammo. It did not shoot very well so he used it for training. Suddenly, after 300 rounds the ammo shot better than anything he has ever used. That was the worst case of ”getting used to moly” I know of. Usually it takes 5-30 rounds to get enough moly into a worn barrel. A new one is much easier, just shoot moly bullets during the break-in.

Some people are afraid that tumbling their bullets will work harden the jackets. We ran some Berger bullets for 5 hours in our rotary tumbler and checked hardness – exactly the same or 137 Vickers / 1kg.

A test was also done to see if time changed neck tension but we were unable to see any change at all.

One important thing Kevin is pointing out in his article is that moly and wax should not be in the chamber. Too many shooters don’t clean their chambers. I’m not talking about you bench rest guys now.
We are using OKS fine moly, 0,6-0,8 micron. Well, that’s about all we have done with moly. The commercial product has been very successful for us and we can’t see any reason not to continue.

Good shooting

Norma Precision AB
Christer Larsson, R&D

 

[bootlaceb]

German1

Thanx for the info. I think it makes the whole thing far more understandable for most.

 

[GermanS1]

I'm glad that was useful. While digging I also found an old piece by David Tubb about moly, so here it is. Hopefully this will keep everything in one place and make future searches easier.

Moly-Coating: A Champion’s Perspective
David Tubb

MOLY EXPLAINED
Coating bullets with molybdenum disulfide,MoS2) is not a new idea. Recent popularity increases due to the ready availability of coated bullets and various bullet coating kits, however, have brought moly coated bullets to the forefront of discussion among competitive shooters.
Obviously, I think moly coating provides the shooter with superior performance; as you may know, I own and operate Moly Coatings Inc., which we believe to be the premiere commercial facility of its type. I wouldn’t have invested in this operation, however, if I didn’t believe that moly coating provided a viable performance increase and, certainly, if I didn’t believe that the advantages far outweighed any drawbacks.


My focus in this article is giving an overview of what moly coating accomplishes, why it does so, and share a few tips I have used successfully to get the most benefit from this technology.

MOLY EFFECT
Moly coating accomplishes one main thing: it greatly reduces friction between bullet and firearm bore. This effect is shown in several ways and, likewise, has various singular effects on the bullet. All these effects are positive.

The foremost effect, in my opinion, of reduced friction is that moly coating makes it possible to increase bullet velocity at the same chamber pressure.

For example, if we take one specific load that uses an uncoated bullet and simply replace the bullet with a moly coated bullet, velocity will drop. For instance, let’s say a .243 produces 2900 fps with an uncoated Sierra 107 gr MatchKing. The load is 41.5 gr IMR-4350. Replace the uncoated bullet with a moly coated Sierra 107 gr MatchKing and there will be an approximate velocity loss of 40 to 50 fps,,1-2 percent).
Pressure, however, will likely fall from approximately 52,000 psi to 49,000 psi, or lower,about 4 -5 percent reduction). Note that pressure decrease is greater than velocity loss, and this is the key to increased speed with moly coating. Note also that while all cartridge and bullet combinations will respond similarly, some will demonstrate more or less variance between coated and uncoated bullet figures due to many unpredictable variables,barrel configuration, individual component lots, etc.).

We would take the load now and increase the powder charge with moly coated bullets to attain the “old” uncoated bullet velocity level of 2900 fps. Now we’re back at the same velocity as before, but chamber pressures are still lower, so we can increase the charge a little more than that and increase velocity as a result. The net effect is higher velocity at the same or lower chamber pressures. Furthermore, if you only load back to the original velocity of 2900 fps using a moly coated bullet, you will now be working the rifle at a reduced pressure which translates into a longer barrel life and more than likely you will experience an increase in accuracy. Kind of like operating a diesel motor at 2100 rpm vs 1800 rpm -- which one will last longer and operates more efficiently?

Because it is such a tremendous friction reducer, moly also eases bullet entry into the lands. Whether the bullet is seated into the rifling or jumping, the initial contact and acceleration is facilitated with moly coated bullets. Recovered bullets have shown improved jacket integrity and greatly reduced impressions made from the lands. There’s no question that moly coating makes the bullet’s trip down the barrel much “easier.”

DOWNRANGE PERFORMANCE
Other performance advantages from moly coating again come from reduced friction and can be related to enhanced bullet flight. I have found that accuracy is usually better comparing moly coated to uncoated bullets. I believe that less stress on the bullet plays a key role in this. I further believe that moly coated bullets can be more consistent shot to shot and possibly more stable in flight. These differences are difficult to quantify due to the great number of variables that come into play when shooting 600 yards and beyond.


One entirely plausible reason for enhanced flight is again due to lowered friction:
a moly coated bullet will enter the bore much easier and, therefore, probably with less disturbance to the jacket and less stress on the core. Recovered moly coated bullets usually exhibit shallower rifling impressions, and these impressions have a more uniform appearance.

BARREL LIFE
I have found that moly coated bullets provide extended barrel life. I believe that the coating itself provides a “buffer” of sorts between the powder gases and barrel surface, and also that moly coated bullets result in less heat being transmitted to the barrel. Many time Bianchi Cup champion, Doug Koenig, told me that he can make several more practice runs firing the Barricade Event using moly coated bullets. In this event the shooter secures the handgun barrel against the barricade using his hand:
barrel heat build up dictates how long the shooter can make practice runs.
Again, moly coating reduced heat build up sufficiently that Doug could get in 3-5 more 6-shot strings before having to stop and allow the barrel to cool.


It’s been my experience that moly coating adds at least 20 percent to accurate barrel life. Barrel wear in a centerfire rifle is almost exclusively due to throat erosion,cracks and roughness in the first 3-4 inches ahead of the chamber caused by heat, flame, and pressure).

An additional 500-plus rounds may not seem like much, but it will add up over the course of a few barrels. However, that, like many advantages of moly coated bullets, are welcome side benefits to the major improvements that result from their use.

CLEANING FREQUENCY
There is far less bullet jacket fouling in the bore with moly coated bullets. Specifically, I have found there to be both less fouling in terms of the amount of deposits left behind after shooting, and a much slower accumulation of fouling. Norma AG found there to be a reduction in metal fouling of 30-40 percent. Now, the amount of fouling any one barrel exhibits has a lot to do with the barrel itself, but I think that this estimate is reliable, if not conservative. I normally shoot between two and three times as many rounds through my barrels before cleaning, depending on the caliber.

The effect here is obvious: I can get many more accurate shots between cleanings with moly coated bullets. In the past, I had to clean after each day of shooting at a major event, such as Camp Perry. Now I can shoot the entire four days there without cleaning.

This is not only a convenience but greatly enhances the consistency of my sight zeros. No matter what steps are taken in cleaning, the first two,or more) rounds through a clean barrel are always a little outside the group,moly coated or not) -- not anymore! This is the sort of advantage that can make the difference between losing and winning.

OTHER BENEFITS
There are other benefits to using moly coated bullets.
Since there is a coating between the bullet and case neck, moly coated bullets will not suffer from the “sticktion” many have reported with uncoated bullets. This dangerous circumstance results from simple corrosion between the bullet and case neck, and the result is elevated pressures.
Likewise, coated bullets won’t tarnish or corrode after handling. And there are others, but -- the reason to use moly coated bullets is because they provide better performance! Shooting them because they add to barrel life or so you don’t have to clean the barrel as often are, again, side benefits.

-----------------------------

 

[spclark]

I received a box of 500 DTAC 115's yesterday, the first batch I've ordered hBN-coated from SSS. Comparing the appearance of these to some I've "home-processed" using 45 micron powdered hBN, I believe David includes the wax step.

His product is very smooth,his look like they're made of bronze) & lack the "powdered sugar" look of mine. Unwaxed seem to work fine out to 600 yards; I'm loading today for 1k yds next weekend... we'll see if the wax matters any downrange.

He states on his website that "this bullet coating process cannot be accomplished with conventional equipment" but a few minutes experimentation gave me 115's that look virtually identical. From this I think the mechanics are the same even if the recipe proportions vary a bit from that used for moly or Danzac.

He'll coat bullets for you for $.05 each in quantities of 1000 or more. Check out -

http://www.davidtubb.com/tcom_images/dtac/bn_coating_information.pdf

- for more info.

 

[RickB]

An often overlooked, though fairly basic, issue with any sort of coated bullets is whether the coating is damaged,or even scraped off completely) seating the bullet. I have pulled a number of bullets of my own loads as well as other people's and it is not that uncommon to have most of the coating gone when using anything other than one of the VLD deburring or chamfering tools even with a "good" coating process.

It is also instructive to carry coated bullets around in your pocket for a week or two to see just how well the coating actually remains on the bullet. Some people have tried rubbing bullets with a cloth or whatever to accomplish the same sort of test.

 

[spclark]

True enough RIckB, but then many of us wonder just where the coating is intended to provide the greatest benefit: at the point where the bullet encounters the lands, or all the way down the bore along the entire bearing surface.

It may not matter much if the coating gets disturbed when seating bullets,if the neck tension isn't too extreme) or that when fired the coating doesn't make it past the first 10% of the bore... if that.

Shooting coated bullets repeatedly in a clean barrel will tend to spread a coating down the bore.

One of the advantages Tubb claims for the hBN process is that cold-bore shots don't deviate in POI from those fired after.,David told me via e-mail this morning his process doesn't use wax BTW.)

 

[GermanS1]

I've pulled hundreds of coated bullets,sadly...) and the coating is practically intact on them. The only bare spot tends to be right at the shank/boatail junction. It must depend on the chamfer, the neck tension, the coating itself and who knows what other variables. It's an interesting test for everyone who coats, I suppose.