Dear Guys,

My coworker says I have to shoot Moly Coated bullets out of my Rem 700 in 300 Win Mag. He says if I don't do this the friction between the uncoated bullet and the barrel will burn out my barrel really fast.

Is that going to happen?

Thanks
-Eddy

Your co-worker is not as helpful as he thinks. With reasonable care, I would expect your .300 Win Mag barrel to last several thousand rounds at least.

Shoot anything fast enough without letting it cool down, and you'll heat up the barrel and burn it out, moly or no.

I have never used the moly coated bullets and have never had any barrel problem. However I never shot the 300 Mag for fun and games and only used it if I had to. A couple thousand rounds should not hurt it.

Looking at the independent test of Molly bullets (not the data put out byt the people who make molly coated bullets), no one seems to have definitive proof that it does much of anything at all.

Do not think bullet/barrel friction is the main problem in barrel wear. If it were, wouldn't barrels wear out at the muzzle faster than the middle section...after all, the bullet is going fastest at the muzzle?

Think barrels are prone to burning out from the hot gas and agbrasion of powder in the process of being burned being forced down the bore. Bullet friction does add to this but the heat of firing set up the situation were bullets wear the breech end fastest.

If you'd like your .300 to live a long life, don't reapid fire it...keep that breech end cool and it will last a good long time without a "kaboom".

Listen to the other posters, and don't take any further firearms advice from your coworker.

Here's the conundrum - moly reduces bullet friction, this causes it to slide faster, the powder gasses aren't allowed enough time to build behind the bullet and therefore, the velocity drops.

To recover the lost velocity, you must add more powder to be combusted. More powder means a longer burning process, which everyone knows equates to more pressure and temprature, the two most deadly forms causing barrel erosion.

Used the moly process for a period of time and became convinced it was a waste of time. Accuracy was no better than with non-coated jacketed bullets - in fact, it always takes a breaking in period to "season" a bore to accept the moly. Then, cleaning the stuff from the bore is a major undertaking in itself. If you ever shoot moly coated bullets then switch over to plain jacketed, then back to moly - you've got a real mess on your hands!

The containers of moly in my gunroom are relegated to non-gun use, just household usage.

Your coworker ever shot a rifle before ? How many times did he think you were planning on shooting in the course of a lifetime. My personal opinion is that there are few shooters who can go out and shoot a couple a boxes of .300 Win mag rounds quickly enough to harm the barrel of most factory guns. This is not a varmint rifle that you could shoot hundreds of times in a day......mine kicks, it lets you know you did something.

Uh huh. Do you remember the look Bugs Bunny used to give the Coyote when he began his speech about being a genius? You have the right to give your co-worker that same look.
Ribbonstone and kdub hit the nail on the head.

Good luck with your co-worker.

Most barrel ware comes from throat erosion and would be noticeable only after a few thousand rounds (old timers used to shoot out the rifling when using corrosive primers and not cleaning the bore). The erosion is caused buy flame cutting when the rounds discharge. The 300 will erode faster than a 30-30 just because of the hotter powder charge. With a Garrand (30-06) they figure 1000 rounds per 1 point of erosion. Accuracy usually deteriorates after 5 or 6K rounds.

Lynn has it right.

A .308, 30-06, and 300mag. all run at about the same max. pressure....if pressure is about equal, then temperature is about equal. Why does the .300mag. erode barrels faster than the .308? Two reasons:
1. The TIME of the burn...more powder just takes longer to burn, so temp. stays high longer. Longer time for heat conduction.
2. Part of every powder charge is being pushed through the bore while the powder is burning...kind of abrasive. More powder, more being pushed through, more abrasion (this is where the sharp shoulder cases claim to have an advantage).
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Know that old example of passing your finger through a candle flame?

In comparsion (keeing the caliber the same), if you burn twice as much powder in a larger case, then consider it as passing your finger through two candle flames...can still do it, but your finger gets hotter. Keep using larger and larger cases, burning more and more powder, is not unlike lining up more and more candles....which is why a 30/50browning MG isn't going to have its barrel last very long at all.