I was just visited by a good friend of mine that was having a big problem with four of his rifles, namely inconsistancies in accuracy with some high $$$$ hunting and sniper rifles.
So i could tell, and even smelling the solvent, that he just cleaned the rifles but.... ALL the crowns were showing signs of corrosion? So i asked him what the heck are you shooting.......moly bullets of something?
I wish i had a camera and a scanner because he had the look on his face like he was just busted for shooting the neighbors butt with a BB gun!

Ok now knowing, i then shot some solvent down the barrel, let it sit for a minute, ran a brush with a patch, and saw a road map to the grand canyon (on all barrels)! And what he got from me was, "i told you so"! Then i explained to him again, (like i did many years ago) molybdenum disulfide just might be slick and make you think your doing good, but your not at all!
Molybdenum actually traps water and even if your barrel sweats, or is effected by climate change, it will attract that water as well and trap it between it self and your barrel. And this does happen to all barrels, therefor stainless is not immune to the reaction moly has (as 3 of my friends 4 guns were stainless).
Plus it's hard as hell to get out and what actually happens is it fills in the corroded holes and etch marks that were created so it's very hard to tell when there is an actual problem (Molybdenum disulfide has a very high working pressure, that's why it's hard to detect it's damaging effects until it's too late, or you use copper again). So now, and with over $1000 to get new barrels, it's copper all the way for him once more.

But now i'm wondering, how many of you guy's use moly coated bullets?

Here is a pic and short article of what molybdenum disulfide does from www.varmintal.com/arelo.htm.......
MOLY/WATER AND CORROSION.... I have performed a Moly/Water Slurry corrosion test on one of my Contender carbine barrels. The picture shows the etched spot on the underside of the barrel just forward of the forearm hanger. I sanded the bluing off of the area and placed the mixture on the spot and waited 1 day. The surface was etched and is rough to the touch. When I get a chance, I will try to measure the surface height with a dial indicator. I am not sure if I have the accuracy with my cheap indicator to do the job. You can test any barrel that you might be concerned about to see if there could be a problem. I would suggest that if you shoot Moly bullets in a regular Chrome-Moly (4140) steel barrel in wet weather, that you clean and oil the barrel the first chance you get. A similar test on my Encore 22-250 Imp/40° stainless steel barrel showed no corrosion attack at all.

I never used them but I have a buddy that does. I was turned off by some of the things I had heard such as accuracy inconsistancys,cleaning problems and the need to "prep'' the barrel with moly after cleaning before shooting again.I figured there was already plenty of variables in consistant shooting without opening up another can of worms.I had never heard of the corrosion problem though.

Only thing I really used were the Barnes XLC line of bullets... they state its not moly and I havent noticed any dire effects from a barrel sitting around. I've since switched back to lead bullets as well.


-DallanC

DallanC, the Winchester and Barnes are different from moly, and i think if i had to shoot a coated bullet, it would be one of them (but i ain't changing any time soon).

The Wheel ain't broke...Copper all the way...

I HAVE NEVER USED THEM AND AFTER HEARING ABOUT YOUR BUDDIES RIFLES I NEVER WILL. MY RIFLES SHOOT AS WELL AS I CAN SO I DONT SEE ANY REASON TO MESS WITH IT.

When moly first came the attention of the broader range of shooters it was touted as an aid to accuracy and reducing barrel wear. Many articles shouted its praise and soon the availability of products ranged from factory coated bullets to kits that would allow handloaders to moly bullets at home. And I jumped on that bandwagon early.

Dissention came slowly; I recall hearing some negative reports at a benchrest shoot. Lots of benchrest shooters had taken up the Moly Mantra and, like all things Holy, we are reluctant to change. Bore scopes were soon picking up the deposits, mostly around mid barrel, that seemed impossible to remove with conventional solvents and brushes. Other problems came to light. Few people use moly today.

Still, this is a pattern that is repeated often enough that one becomes increasingly skeptical. And, that skepticism is often justified. The bottom line seems to be that there is no magic or even technological advents that are going to cure the lack of skill on the one hand or proven methodology on the other. Even legitimate advances (for example the 6mm PPC) take awhile to get established.

Perhaps the shooting sports is one area where we do not want to be the first kid on the block to have the latest and greatest. Personally, I'm tired to be the R&D person for manufacturers and sit contented to allow others to try and decide if it is money well spent. As such I have saved a bunch of money (no Geico commercial here) by holding back and not rushing to buy such ineffectual offerings as the WSSMs, the Ruger 204, the Remington Ultra whatevers or other enticements that will eventually be relegated to the increasingly large trash heap of obsolesence.

Hi

Wow. This place is great! I love hanging in a place where people do real research or the EXPERIMENTATION to VERIFY a theory.

The Scientific Method ROCKS!

I'm getting close to barrel break-in, and had been considering moly bullets for that part of the project. I'd read some about problems, so I was still in the research phase, anyhow.

So, I'm thinking copper for me as well, thanks. ...and thanks for the picture of the empirical results, too, 10ring!

....

Scientific Method?!?!?

Yeah yeah yeah, I know I know. "I'm just an elk hunter." ANYONE who has an idea of how something works, does empirical research to verify the idea, revises the idea to make it work BETTER and does more experiments to verify the NEW idea is a SCIENTIST. Physicist, police detective, or elk hunter, the Scientific Method ROCKS!

Having worked professionally in the ordnance field , and using molygreases , I saw that one coming when they first started praising it .. The grease is slicker than owl s*** , and is made for high temps and high resistance uses .. No way I'm putting that crap down one of my barrels , I did run one box of XLC's thru my 375 , but never again , very difficult to clean out ..
I'm with you Handloader , I dont jump for the newest gee whiz flash banger that comes out .. But they have to sell stuff , and one way is to put out new stuff , that supposedly obsolesces everything before it ..
Jack

And i forgot to mention that after the EXTENSIVE cleaning, i looked down the back of the barrel (.308 that was LESS than a year old) grabbed a regular 'ol .30 cal bullet, lined it up with the hole and dropped it down. Well with not one scrape or scratch on the bullet it self, it came out the other end and was resting on my foot!
It had expanded the barrel specs. just shy of an 8MM @ .3120B and .3198G diameters, so the Moly had compacted/degraded .0120B and .0118G of the barrel.
It really makes me sick! Although i am glad i can share this type of info with you guys!

Bushmaster & robfromaz1977, I agree 100%


Thanks guys for the info...

WOW! Thanks, Guys. You may have saved one more forum member from an expensive mistake.

Thanks for the info.

515034s10ring,

I've stewed over your posts and really needed to make some comments and ask some questions.


First, I'd love to know how you measured the bore. What devices do you have at you disposal to make an accurate bore (land and groove) meauserments? Obviously your a barrel maker and have the equipment to make these measurements. The age of a barrel is immaterial. How many rounds were fired with coated bullets? What was his coating process? Cleaning procedure?

Second, please explain how bullets made of considerbly softer material than barrels could expand a barrel. The case and action are the weak links in the firing process and would have gone south long before any barrel expansion. Tests ( ref. Handbook for Shooters and Reloaders, P.O. Ackley) have shown an over sized bullet, as much as .030",simply swages down to the bore diameter when fired through a .308 barrel. I, without going into detail,personally can attest to the fact a 308 diameter bullet will pass through a .284 bore without any ill effects. Even if somehow the moly layered in the bore to the extent you suggest, a bullet would have simply conformed to the reduced bore diameter. Since moly is a lubricant, the swaging would have been easier due to the reduced friction. Recovered bullets fired through moly coated barrels clearly show a marked reduction in bullet deformation. Pressure/Time curves show a maximum peak at approx. .2ms into the firing process and a marked drop at .5-.6ms. This drop is due for two reasons. One, the effective chamber volume increasing after bullet movement and the bullet conforming to the bore diameter. Pressures then drop and remain at approx. 10% of the peak till bullet exit time. Of course powder volume, case shape,volume and powder type will alter this somewhat, but in any case, the effects of the bullet engraving are the same. Also note the velocities drop off somewhat from the use of moly and generally require a increase in powder charge to attain the velocities of bare bullets due to the reduced friction and lubrication effect engraving the bullets, but you understand all this anyway. Correct? In any case, the case and primers would have blown long before any barrel expansion took place.

Third, although I don't use moly today,I have used it in four Hart SS 1K barrels, two 308 Super (30-8mm Mag),one 6.5-06 and a 30-338 collectivity firing thousands of rounds without anything even remotely approching a .012" buildup. In fact, I nor the smith I worked with at the time, wouldn't have had a way of determinding the coating thickness. Two of these barrels were later turned to a sporter contour and continue shooting acceptable groups today,ie sub moa.

Fourth, please enlighten us with your "Extensive" cleaning method used to remove the moly buildup of .012", and how without the use of a bore scope you could see "a road map to the grand canyon" in the bore?

Is it possible your friend mistakenly used grinding compound to coat his bullets instead of moly?


I respectively await your reply.

Bill