Educational Zone #169 – Accuracy of Moly Coated Bullets

Well, winter is nearly over and it was finally nice enough to make a trip to the range this morning.

I was recently given some “coins” in the ARFcoin Exchange Thread.

I used mine to claim prize #9 which was two boxes of Nosler .224, 55 grain bullets that were donated by my friend NineLivez.

He shipped them to me and here they are.

These are some very nice bullets and I looked forward to trying the out in my Savage bolt gun.

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But I decided I wasn’t just going to burn them up, but would try to learn something while I was shooting.

I have been coating some of my rifle bullets with molybdenum-disulfide, commonly called “moly”. This is a black powdery substance that can be coated on bullets to lubricate them and reduce barrel fouling. I have written about this process before here: Moly Coating Rifle Bullets

By impregnating a copper jacketed bullet with a moly coating, it will lubricate the bullet and reduce the friction as the bullet goes down the bore at high velocity, thereby reducing copper build-up in the bore. This allows long strings of shots between cleaning without any reduction in accuracy. And, as an added bonus, when you do clean the bore, it cleans much easier, as there is less fouling.

But I was wondering, “Will moly have any effect on accuracy?” I knew it made clean-up easier, but I wondered if accuracy would be better, worse, or just the same.

Here was a golden opportunity to do a test.

I took one box of the bullets and ran them through my moly coating process.

Here they are in the vibrator, before tumbling.

Here they are in the vibrator, before tumbling.

And here’s what they looked like after the process, compared to the non-coated bullets.

And here’s what they looked like after the process, compared to the non-coated bullets.

I prepared 60 cases exactly the same.

They were once-fired in the bolt gun, cleaned in my wet tumbler, neck-sized only, and then primed with benchrest primers.

I then charged them with a good load of one of my favorite powders and loaded half of them with the non-coated bullets and half with the moly-coated bullets.

Here they are, all snuggled in their box like a bunch of cobras.

Here they are, all snuggled in their box like a bunch of cobras.

Time to go to the range.

But the weather turned sour and I had to wait a couple of weeks for some clear weather.

Today was the day.

Continued below...
Here’s the set-up for the rifle.

Here’s the set-up for the rifle.

I will be shooting at 100 yards. It was clear and cool (around 50 degrees), with a little more left to right wind than I would have liked, but here we go anyway.

I had cleaned the rifle bore very well at home and dried it.

I shot a couple of fouling shots to foul the bore and settled down and shot 5, 5-shot groups on one target with the non-coated bullets.

I then cleaned the barrel really well again.

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It took some time, but I kept at it until the patches were white.

I then fired a couple of fouling shots with the moly bullets.

Then I shot 5, 5-shot groups with the moly bullets.

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When I got home, I used calipers to measure the groups. I averaged them and converted them to Minute of Angle.

Bottom line:

Non-moly groups averaged .7637 MOA.

Moly coated bullets averaged .674 MOA.

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Conclusions:
  1. Understand that this was one test, with ten 5-shot groups, with these bullets and this rifle. We can’t draw any firm conclusions about “all bullets” or “all rifles”.
  2. But in the case if these bullets and this rifle, it seems that the moly coated bullets shot slightly better.
  3. It was much easier to clean the barrel after shooting the moly bullets, than with the non-moly bullets. This is because the moly helps prevent deposits of cooper fouling in the bore.
  4. It surely did not make the bullets shoot less accurately by moly coating them.
  5. Moly allows long strings of shots with less barrel fouling in my rifles.

Oh well, not much of a surprise for me, as I have noticed this in the past, but wanted to do a test to confirm my experience.

Thanks to NineLivez for donating the bullets and thanks to my friends for donating the “coins”.

It’s fun to shoot stuff.

 

1 Comment on Educational Zone #169 – Accuracy of Moly Coated Bullets

  1. George Steele // March 28, 2017 at 8:10 pm // Reply

    I read your other post on moly coating. Then, as now, I wonder if the comparison is apples to apples. It seems to me that banging the bullets together in the tumbler for 15 minutes could well introduce irregularities (you said it was the loudest you will ever hear from a tumbler) into the bullet jacket. I think to know the real difference, you’d have to put one set of bullets in the moly tumbler, and another set in a tumbler with no moly, tumble both for the same amount of time, and THEN load them up and compare group sizes. Or, manually rub in some moly, using plastic gloves, and do the same kind of test comparing uncoated bullets out of the box. Just a thought. One other thing: wouldn’t the neck tension on the moly bullets result in a less-tight grip on the bullet, like a looser neck? I would think the lubricity of the moly would make the bullets easier to pull, and slip out of the neck more easily than would be the case for the unlubed bullets. Thoughts?

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