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Discussion Starter #1
Ok, I am kinda curious about mollys. All I really know is that they are supposed to be better for your barrel. And I think your not supposed to fire normal/uncoated bullets through after you have used mollys right? Anyways.... any info would be appreciated. Thanks in adavance (yet again :D )
 

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Well, Moly is another one of those barrel break in type questions. There is not a whole bunch of concrete proof that it does anything for your rifles accuracy, though it generally can make it easier to clean the barrels. Yes, you are correct, once you go to moly, you need to STAY moly.

Personally, I do not use moly bullets

MEL
 

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The term "Moly" refers to Molybdenum Disulphide. This is an extremely fine powder which acts as an intert lubricant between the bullet and teh bore. It is coated onto bullets to reduce the friction incurred on the bullet as it passes down teh bore. The reduced friction is said to prolong barrel life... increase accuracy and velocity and BC. The moly coating does not build up in the barrel... since each successive shot removes any excess material from the previous round. If it is a new barrel... dont use moly anyway... the extra friction from a non moly bullet is needed to break in the bore.

Now... your probably thinkin Moly is more cool than sliced bread right? Not exactly... there are a few negatives you should know about.

The largest downside is that moly is hygroscopic... meaning it is capable of absorbing water from the air. This water is then trapped between the moly coating and the barrel... which is definitly not a good thing. A quick fix to this problem is to run an oiled patch through the barrel after each shooting essions. The oil will block moisture from being absorbed. Moly is also extremely messy... and it likes to stick to everything... especially the muzzle crown. It is also easily rubeed of of bullets... leaving a slippery film on whatever it touches.

The largest threat to barrel life is not addressed by the use of moly coated bullets... THROAT EROSION. Throat erosion is not cuased by friction of the bullet... rather the high pressure and high pemerature gases that are present in every shot. It is not very often that a rifle barrel wears its rifling out before it suffers from extensive throat erosion.

I use to use moly coated SMK's... but i never saw any real evidence that they improved my shooting or the end results any over the standard SMK's in numerous rifles and calibers.

BC
 

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mele said:
though it generally can make it easier to clean the barrels.

MEL
All you do to clean a moly impregnated barrel is push one oil soaked patch through... then 5 dry ones... then one patch with a protective oil to keep the Moly from obsourbing moisture from the air.

mele said:
Yes, you are correct, once you go to moly, you need to STAY moly.

MEL
If you dont clean out the moly then yes you have to stick with moly bullets for the remainder of time untill you do clean out the moly. Once you clean all the moly out of the barrel... using shooters choice... or a few other choice cleaning products (most solvents wont even touch Moly... you need to use a specific solvent that is "Molybdenum Disulphide" rated) ... you can use regular bullets again. Just make sure to get ALL of it out.

BC
 

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Ok this may be a stupid question but im going to ask it anyway. Once you go moly, why cant you shoot a normal bullet anymore?
 

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Once you shoot copper jacketed bullets through a moly coated barrel it impregnates the moly into the bore... making it EXTREMLY hard to get the Moly out... even with Moly Solvent. You really really have to scrub that stuff out... and it can be a huge pain in the rear... why do ya think i stoped using moly bullets? :)

BC
 

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Discussion Starter #8
So this is a little old but I want to know a little more about moly coated bullets. It seems to me that molys might be a little messy, but do they actually extend barrel life and/or provide any advantage whatsoever?
 

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I have heard from many people that the moly's can ruin your barrel. I have yet to see any hard evidence saying otherwise. My advise would be to not use them. Plus they seem to be more expensive.
 

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Hi,

I found this from Norma Precision about moly:

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
 

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Discussion Starter #11
hmmmm..........what does eveyone think of that?

And thanks for the info!!!
 

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As per the Hart Barrels Website - .... What about Moly coated bullets?

? We do not recommend the use of moly bullets, as we have not seen an increase in accuracy or barrel life from using them. We have measured moly buildup up to .0005 for the first 2 - 3 inches in a barrel. We have not found a cleaning method that adequately removes the moly without potential damage to the barrel. If you elect to use moly bullets, we recommend that you contact the bullet manufacturer for details on the cleaning method they recommend.

As per the Lilja Precission Rifle Barrels website - Q. What is your opinion of the use of moly coated bullets?

A. First, as described in our section on barrel break-in, we do not recommend the use of moly coated bullets for break-in. The break-in process requires the use of an uncoated jacket if it is to be successful.

Secondly, at the risk of offending those that promote the use of moly, we can't see much benefit to it for a couple of reasons. There are two basic claims made for the use of moly, reduced fouling and increased barrel life. We'll look at both of these.

We agree that bullet jacket fouling in a barrel can and will cause accuracy problems in a barrel. But for the most part, jacket fouling in a hand-lapped, match-grade barrel is minimal. For the small amount of copper fouling that does remain in most barrels, conventional cleaning methods can and will stay on top of the fouling. We recommend cleaning solutions like Shooter's Choice and/or GM Top engine cleaner mixed with Kroil oil and the limited use of Sweet's solvent. Our suggestions for cleaning can be found in the Cleaning and Break-in section.

We have examined barrels with our bore scope that have had an excessive amount of moly fouling layered with powder and jacket fouling. The only way we could remove this buildup was through relapping of the barrel. Perhaps part of this type of problem results from a mindset that says "Hey, I'm using moly now and I don't have to clean very often." So if you do elect to use moly coated bullets we recommend that you still clean as often as before.

So, the obvious question to us is, if regular cleaning is still required with moly and if a bullet/cartridge/barrel combination does not foul to any great degree without moly, what is the advantage to moly?

This leads us to the second part of our answer. Some of the promoters of moly claim an increase in barrel life. While this sounds good on the surface we must ask the question: what causes a barrel to shoot out? Barrels wear out, or no longer shoot up to their original performance levels, because of erosion to the throat area of the barrel. This erosion is caused by heat and pressure created by burning powder. As a throat lengthens, velocities fall off and accuracy can suffer too. Eventually more and more of the throat will be eroded and moved forward. Also the diameter of this eroded section will increase. We have seen take-off barrels that had fully 1/2 of the length of the rifling completely eroded.

The key to this type of erosion is that it is caused by hot powder gases under high pressures and not by friction between the bullet and the barrel. We have read a report from a military test that examined this type of barrel wear. It was found that over the course of tens of thousands of rounds the actual groove diameter of the barrel was only increased by a few ten thousandths of an inch. It is this type of wear that moly might prevent or slow down. But in this test the throat area grew progressively longer and larger in diameter from gas erosion, not friction between the bullet and barrel.

So from our point of view, moly coated bullets are not going to prevent the type of throat erosion we have described, that the type of wear caused by friction between the bullet and barrel is insignificant, and that the prevention of jacket fouling through the use of moly is marginal at best and that moly may add another type of fouling to the barrel.

There is one type of shooting that may benefit from the use of moly coated bullets, in our opinion. In an effort to find the "perfect" bullet, target shooters using the 50BMG cartridge have manufactured solid bullets that are lathe-turned from materials like brass, bronze, copper and even soft steel alloys. These bullets can cause a considerable amount of barrel wear caused by friction between the barrel and bullet. The bore and groove diameters of these barrels do increase in diameter as a direct result of this friction. And this wear is not caused by the hot powder gases that will erode a throat in more conventional barrels.

In this case it seems as though, in our testing, that coating bullets with moly will help reduce this type of barrel wear.

We realize that our opinion of moly does not go along with the wisdom and promotions of the day. But we're willing to listen to opposing views if you have one.

Post Script: In the January, 1999 issue of PRECISION SHOOTING Magazine there is an excellent article by Kevin Thomas of Sierra Bullets about his experiences with moly. I would suggest that anyone considering using moly read that article first. In summary, Kevin found almost the same results as we've outlined above. In short he found that moly had no effect on extending barrel life in their controlled accuracy testing of bullets during production. He did not see any improvement in accuracy and to the contrary even found some degradation in accuracy at times, and that moly could create its own fouling problems. Mr. Thomas found that moly did reduce jacket fouling a little but that a regular cleaning schedule was still required. Like us he wondered what if any benefit there was to using moly?
 

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Discussion Starter #13
Thx for the info guys, I've decided I am goin to stay away from Molys. Maybe the technology will improve someday, but there are to many variables, and that is something I don't need.
 
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