Moly coated bullets extend barrel life. Hype, fact or...?


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NoAlibi
September 28, 2011, 04:40 PM
I've been shooting my AR in .223 averageing 200 to 300 rounds a month. So far I've put ~2,000 rounds of Win. 55gr fmj bullets reloaded @ 3,200fps through this chrome lined upper and I haven't seen any decrease in accuracy yet.

However, from some of the tales I've heard I am getting concerned.

1. How may of the above reloads can I expect to shoot before accuracy seriously deteriorates?

2. If I started with a new chromed lined barrel how many moly coated bullets can I expect to shoot before accuracy seriously deteriorates?

Thanks...Doc

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rcmodel
September 28, 2011, 05:17 PM
The bullet doesn't wear out a barrel on a high power rifle.

Heat and abrasion from the burning powder is what wears out, or more properly, erodes away the barrels throat right in front of the chamber.
The higher the pressure and velocity of the load, the faster it happens.

Prolonged rapid fire without letting the barrel cool also shortens barrel life drastically.

When the erosion gets bad enough, and far enough down the barrel, accuracy will suffer.

And if all you are shooting is FMJ bullets, it won't make much differance anyway.
They are the least accurate bullets made to start with.
Here is the differance good bullets can make.

Same load, same rifle, same target.
Only differance is the bullets.
55 grain Win FMJ-BT and 55 grain Nosler Ballistic-Tip.
http://i81.photobucket.com/albums/j219/rcmodel/KTOG/EoTecGroup.jpg

But I'd say with only 2,000 rounds through a chrome-lined bore, you have a ways to go yet!


rc

Sky
September 28, 2011, 05:41 PM
+1 rcmodel

W.E.G.
September 28, 2011, 06:50 PM
You'll probably damage your barrel with a cleaning rod before you damage it from shooting one type of bullet versus another.

With normal use (absence of multiple mag-dumps), and conservative cleaning methods, you should get 20,000 rounds of service from a chrome-lined AR15 barrel before you see any clear degradation of practical accuracy.

The condition of the muzzle is what governs most accuracy issues. By the time the "throat erosion" meets the muzzle, most will agree it is time to replace the barrel. Short of that, you will get disagreement.

Funshooter45
September 28, 2011, 07:54 PM
.223 rifles are not known for eating barrels. They don't use a whole lot of powder and only launch bullets at 3200 fps. On the other hand, calibers such as 220 Swift, 223 WSSM, and to some extent the 22-250 can burn up a barrel fairly quickly if they routinely shoot the max velocity loads which use a lot of powder.

A chrome barrel will help a bit for sure.

Incidentally, Winchester CLAIMS that using ball/spherical powders is easier on barrels because those powders burn cooler. Of course, all Winchester powders are spherical, so it's natural to hear them make that claim.

I don't lose a lot of sleep over how fast my 22-250 barrel might be eroding. But nevertheless, I have developed a good accurate load for it using just 31.5 gr of TAC for those plinking sessions when 3200 fps is plenty good. I keep the hot loads with a heavy dose of Varget reserved for varmints when I might need max velocity and range. I don't know if it will really prolong the barrel life or not, but hey, at least I'm saving 5 or 6 gr of powder every shot.

bds
September 28, 2011, 11:14 PM
H335 (flattened ball powder) in my AR FTW! :D

Did anyone mention the barrel wear from hard carbon fouling?

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