Moly Coated .308s

[Ike666]

In my haste yesterday, I grabbed a box of 168 gn Hornady BTHP Match off the shelf at my LGS. Wasn't paying enough attention and when I got them home they were the moly coated variant.

What's the down side of loading moly coated bullets? They look to be a mess but I can deal with that.

Never used moly bullets. The rifles all already have well broken in barrels. Will the moly foul the bore beyond repair?

Should I keep them if see if they shop will trade me for what I want? (I haven't opened the sealed inner bag).

[carsinc]

I've never used moly coated bullets in a rifle, however I have used well over 1000 moly coated 200 gr swc bullets in my 1911 and they were entirely satisfactory. There are different opinions, plus and minus. Overall, one box of moly coated bullets probably won't matter a lot.

[William T. Watts]

A moly fouled barrel is virtually impossible to clean, I don't know if 100 rounds is sufficent to foul a barrel or not. Fouling may/will occur within the first few inches or so of the throat/rifling, (when fouled there will be a ring in the barrel). None of our instructors at Trinidad St. Jr. College encouraged us to use this product. If your going to use Moly your barrel needs to be Copper and Carbon free (spotless) before using them, otherwise the moly is deposited over the copper & carbon in the bore. FWIW moly can be removed by thumbling bullets in tumbler! William

[Ike666]

William, thanks I didn't know that was an option. I'll probably give that a try.

[William T. Watts]

Ike666 I removed the moly coating from some Partitions that I found on gunbroker that were reasonable, figure 2-4 hours but it will come off. William

[Unclenick]

I have shot moly for years without any of the problems others claim, and I do have a borescope I track the condition of my barrels with. I have seen it suggested in Precision Shooting and other places that when moly first became a craze, a lot of low quality moly got was put on the market in an effort to cash in, and surplus moly of all grades and some with iron and high free sulfur contamination was sold and caused rust pitting and basically spoiled the reputation of the moly system. The original NECO product uses lab grade moly and a wax overcoating that takes the mess out of handling it, and has never given me any hint of a problem. If the proper grades actually damaged bores, you can bet the major makers wouldn't risk it spoiling their reputations by selling pre-coated bullets.

You can buy Boretech's moly cleaner if you want easy removal, but I just use Gunzilla. A wet patch run through and the bore allowed to stay wet with it overnight softens the carbon the moly is mixed with in the fouling, and lets you wipe it right out on the first patch the next day. Any of the mild abrasive bore cleaners will also remove it.

That said, there are pluses and minuses to moly. Some guns—those with rough bores—can take longer to foul-in. Ten shots or even twenty. If you want to switch between moly and plain bullets, you also have that kind of fouling period before the new regime fully settles.

On the plus side, Walt Berger suggests moly bullets self-center better on their way into the throat. He explains that is likely responsible for the slightly higher ballistic coefficients they have at long range. The straight aligned bullet suffers less initial yaw at the muzzle due to muzzle blast, so the bullets go to sleep sooner, reducing the average drag on them during flight. IME, that self-centering also makes seating depth less critical.

Using moly also lowers the cartridge's start pressure, so you may need a little more powder to get the same velocity, but when you add that extra powder the peak pressure is not as high as without moly. As a result, you can either add still more powder to get maybe an extra 50 fps of velocity before the pressure max's out, or you can stick with your pet load velocity and have it produce that velocity at a little bit lower combined temperature and pressure, thus extending throat life. My own AR's barrel has as many rounds through it as my dad's does. He uses plain bullets and shows the classic alligator skin heat stress cracking in the throat in the borescope. Mine still has none. But YMMV.

[William T. Watts]

You can't minimize the need for a copper free spotless clean bore plus more expensive bullets nor the extra expense for specific moly cleaning products. For most people it's a no brainer, why should they take on more expense (bore scope) spend more money for products to clean their moly fouled barrels that may or may not work. I like Hoppes bore/Shooters Choice cleaner (or similar products), JB bore cleaner once or twice a year and I'm done. I do not like moly nor would I encourage anyone to use the product period, it's bad enough to have to deal with copper, mixing copper with moly is not a good idea! William

[zfk55]

It's a narrow world you live in, William. David Tubb used it for years in every national match and all of those he won before switching exclusively to hBN for every barrel he has.
We use hBN exclusively on some 30 rifles and Moly on one dedicated long distance rifle. Its easy to use and very easy clean out.
We have an entire instructive thread on both, and they both serve their intended purpose. They simply double and (in the case of hBN) triple barrel life.
Why try to discourage someone who's not had the chance to make their own determination?

[Doodlebugger45]

I had no idea it was such a big deal. For the most part I don't mess with moly bullets, but awhile back I stumbled across a great deal on some Sierra bullets for my .270 WSM from a guy at a gun show. He did the moly coating himself. He was basically retiring from bench rest shooting and clearing out his components, so I bought the 300 bulets that he had there. I doubt if the moly coating had anything to do with it, but I ended up getting the best accuracy groups I have ever had from that rifle, so I am sticking with that recipe until I shoot all those bullets. I clean my rifles after every trip to the range. I just spray some of the foam Wipeout stuff down the barrel and set them there overnight. The next morning I wipe the bore clean and maybe run a patch with Hoppes in for good measure. So far I haven't noticed any difference between cleaning with those bullets compared to any other bullets.

[Unclenick]

Moly coating got started in part because it reduces copper fouling so dramatically. Indeed, some early adopters thought that meant they didn't have to clean the barrel for a whole match season. Well, you run two or three thousand rounds down a bore without cleaning and unless it is running as hot as a machinegun barrel, something will accumulate. Add to that all the cheap and coarse particle moly that got turned loose on the market, and I think that's another source of the belief that moly causes build-up problems. Those guys tried to get it to do something the inventors never claimed it would, then tried to blame the product for their resulting troubles.

As to why make the switch, in addition to what I outlined and potentially doubling barrel life (note that Norma licensed the original NECO moly process rather than the later, cheaper knock-offs)? I'll tell you how I got started using it:

I shot mostly pistol competition from the late 70's through the mid-80's, when I got started in service rifle match shooting with the Garand. I went through the DCM (later replaced by the CMP) clinic and got a certificate to purchase my first Garand. I went on to match accurize it. The first test I ran with it used 168 grain MatchKing handloads that put 10 shots into 0.7" at 100 yards. It didn't hold that initial degree of tightness for very long, but stayed a 1 moa gun for quite awhile. (The accuracy job on it is a whole other story for another time.) The two germane points are that I now had a rifle that could potentially clean targets and that this was all with the original military barrel, whose bore was quite rough.

Shooting the National Match Course, I quickly noticed a trend. The NMC has you go through 30 rounds before you get to the 600 yard prone slow fire stage. During the first 10 rounds of SF, the gun would show its potential if I did. Mostly 10's and X's, with me throwing the occasional 9. But as it went through the second half of the 20 round string, the X's pretty much stopped, the 10's became scarce and the 9's turned to 8's and even the occasional 7.

At first I though it was just me getting tired. But it happened in exactly the same place in every match. Plus, when I got home, it took most of the night with patch after patch of Sweet's 7.62 to get the copper to finally stop coming out. At Perry, if there was more shooting the next day, this cut seriously into R&R if I didn't want to be up all night with it.

Well, I finally put 2 and 2 together and realized the accuracy fall-off in rounds 40-50 were due to the really heavy copper build-up. So, I tried the then-new moly coating process, and bingo. No more accuracy loss. It would now shoot even an 80 round match with no problem. Cleaning took less than half the time, I and I was a much happier camper. Back then we didn't have KG-12 or Boretech Eliminator or any special moly cleaning gear, and I didn't have any issues. I really think the bad reputation came from cheap, inappropriate grad moly and misuse in terms of cleaning practices. I can't recall when I started using Iosso Bore Cleaner (a mild abrasive, like JB Bore Compound) but it's been around awhile and I don't think it left much moly behind at all.

I have yet to try the hex Bornon Nitride, but IIRC, its coefficient of friction is half that of moly.

[Ike666]

Well, this has been fascinating. Supposing I don't tumble-clean the moly coated bullets, it sounds like a good soak with Gunzilla (gotta love that stuff) and regular cleaning and I should be good to go.

Do I need to clean the bore with Sweet's BEFORE I shoot the moly bullets?

[Unclenick]

I would get all carbon and copper out to start. I use Boretech Eliminator most of the time for metal fouling now. Non-toxic and has the least odor of anything (my wife can't tell when I'm cleaning guns, now) and it works faster than Sweet's. The KG-12 is faster, still, and eats and even bigger volume per wet patch, but just turns brown instead of blue, so it's a little harder to tell when you're done (though usually you are with just one patch). I still remember my eyes watering from using Sweet's.

For carbon, Gunzilla keeping the bore wet overnight or longer will get it all.

[William T. Watts]

The use of Moly was covered thoroughly with our instructors at Trinidad St. Jr. College (Gunsmithing), to a man no one recommended Moly. I am absolutely sure nothing bad is going to happen if I don't use the product, on the other hand I'm not that convinced something bad won't happen if I do use moly covered bullets. William

[Unclenick]

And that's not unreasonable. There were plenty of people with bad experiences from the early blind rush to get on board the moly coating craze by vendors who didn't know the difference between junk moly and the method of producing the super thin coating that had been carefully developed over time by the late Roger Johnston at NECO. I'm sure your instructors had to put up with customer's problems because of those sources of inappropriate materials and methods. But doubling barrel life, when you can get it, buys a lot of special cleaner. And if you you use the process properly, no borescope is required. I only mentioned it as the evidence I have that the system, used correctly, causes no problems. I was shooting moly long before I got the tool.

[zfk55]

Fair enough, William. I've noticed that the one aspect of Moly impact coating that seems to be missing from virtually all of the info I've read in the past 5 years is heat. Lots of heat. So hot that you can barely hold the projectiles coming out of the vibrator. Our coated projectiles are easily twice as difficult to scratch as Sierra's.
I learned the complete process from Stewart Wilson in Arizona. He coats them by the thousands for his rifles sold to Security Contract companies, the FBI and specialty troops within the military. (He's also in the R&D with EDM and his prototype is the new line for EDM this year. Wilson is Mr. Windrunner. His design)

Having used both Sierras and the Neco process coated projectiles, the difference was immediate in chrono'd velocity drop. We only have one Moly dedicated rifle, and that one is a Wilson AR10. (We got lucky)
Cleaning is regular after 300 rounds and we use Wipe Out. We borescope with a Hawkeye after every shooting session.

hBN is a completely different world, and literally every other rifle in the armoury is bore slurry coated and shoots only hBN impact coated projectiles from the commercial 22-250 right through all of the military rifles up to 30/06.
I'm a firm believer in hBN. The Hawkeye borescope is the proof.

I've heard stories about increased accuracy with hBN, but we've not noted that at all. There is a pattern of good SD though, assuming that all of the case and projectile prep are correct.