Stainless steel barrels: how long are they "combat accurate"?

[sinister]

Once a stainless barrel has hit its end of useful life you'll start seeing accuracy suddenly drop off a cliff. Groups will start growing and shots will be off-call. Commercial chro-moly or chrome-lined GI chro-moly vanadium barrels lose their accuracy edge over a gentler decline slope.

A barrel dies at its throat and muzzle. Your best tool for checking is a borescope, but proof will be on-target performance.

If you're shooting real M855 or M193 I doubt you'll notice as that shit will group all over the side of a deuce-and-a-half, relatively speaking. GI MILSPEC acceptance of the gun-rifle combo is within 6 MOA, although real life has it around 1.5 - 2 MOA. If you never shoot past 100 yards you'll probably never notice.

Military armorers almost all use a throat erosion gage which does nothing except show you how big the throat is and how far your leades may be eroded. These measurements are all relative if you didn't gage the gun as-new before you started shooting.

A chrome-lined barrel seems to last longer, but borescoping and sectioning still show throats erode and chrome wears and chips on the highest points of rifling leades where bullet ogives initially contact rifling lands.

[Shabazz]

For a longer lasting SS barrel, get a Noveske polygon rifled barrel.

This is my personal opinion. I do not work there.

[DreadPirateMoyer]

Wow. This forum is an absolute treasure trove of information. Huge thanks to everyone who replied.

I think, with all of the knowledge I've gained here, I'll be sticking with carbon-steel (nitride or chromed) barrels, as I'm shooting for 3 MOA accuracy; it seems like, by the time a SS barrel reaches this point, it will already be rapidly decreasing in the precision department.

Babam!

[RyanB]

I don't care if he's a Tier 0 operator in Echo Force. That's a load of shit.

Nothing personal against you as you're just relaying the information. But seriously - LOL.

M855 is well known to be ~ 4 MOA ammo. Certain lots are even worse. I'll be generous and call it 4. That means that the guy is claiming consistent groups that are 1600% smaller than average.

Let's look at the scale of that error:

- If the average adult is 6 feet tall, this dude's adult is 4.5 inches tall.
- If the distance from California to New York is 2900 miles, this guy only has to drive 181 miles.
- He can fly from New York to London in 26 minutes.

I think that should do it. This one can be confidently placed in the "debunked" pile.

Your meter needs recalibration. I was mocking him.

[a0cake]

Your meter needs recalibration. I was mocking him.

I know; I'm making fun of him with you. That's why I tried to say I understood you were just relaying and not endorsing it at all. Sorry if that was unclear.

[a0cake]

I usually think you're full of it yourself, but that's pretty damn funny!

Interesting. Not sure why that was necessary - wish you'd leave GD disagreements there. The technical posts I make that involve quantifiable information should stand on their own and be challenged on their own merits not because of disagreements about religion and politics.

[RyanB]

I know; I'm making fun of him with you. That's why I tried to say I understood you were just relaying and not endorsing it at all. Sorry if that was unclear.

No worries. I drove 600 miles across four states today, that's my excuse!

[markm]

What are you hens squaking about?

[1859sharps]

I've been heavily considering a Wilson Combat, Larue, or Noveske AR-15 with SS barrel. I know that the above are generally sub-MOA accurate for approximately 5,000-10,000 rounds (depending on who you ask: the manufacturer or bench shooters ), but my question for you guys is unrelated to that. I'm more concerned with the barrel's longevity as a measure of its ability to continue being combat accurate. From my perspective, that's 3 MOA with quality ammo, though I'd be lying if I said I actually had any experience to tell me if 3 MOA is truly adequate in a combat scenario or not.

In reading up on high power matches and equipment a few years ago I can across some comments that seemed to indicate that the that the 5000 - 10000 "rule" came from the Military marksmanship units figuring out a "max" number of rounds on average a particular type of barrel could have put through it and not see any loss of accuracy. Then they would just automatically swap barrels and not worry about it. Basically the theory went they have figured they could shoot say 5000 rounds out of X type barrel using Y type ammo and could almost guarantee no lost of accuracy. then rather than get "caught by surprise" at the 5000 round point, automatically change out the barrel.

Assuming that is true, the military has the budget to do this, most of us don't.

The other source of the 50000 - 10000 round rule seems to be just assuming a 223 would burn out barrels as fast as 308 would. which turned out to not be the case.

I also found credible comments by long time competitors that indicated they could get 15,0000 plus rounds out an AR barrel if they took care of it. basically worked to not over heat it, used the minimum powder charge to achieve their goals etc.

Soooo, what does this mean to the OP. Basically unless you run a max powder load and continually try and fire off a 30 round mag as fast as you can each and every time you shoot your rifle, and unless you get a lemon of a barrel I would think you would get easily 15,000 rounds of life out of it.

At what distance were you wanting to maintain 3moa ?

[justin_247]

Thank you, a0cake, for your posts. I just learned a lot, and for that I am always appreciative.