My old Colt A1 had over 22,000 through it when I sold it and still had plenty of rifling visible.

I never shot out a barrel. I aways trade them away before the barrels get that bad.

You figure 20,000 rounds is 20 cases of ammo. That's over $7,000 bucks of PMC 55gn FMJ. Plus range fees etc.

I'm slowly plugging along on mine...
Almost 4,000 rounds of XM193 and it still groups better than I can shoot it.

A wore out barrel is  going to have diminished accuracy as the barrel gets past the 15-18K, unless it was key holing real bad I don't see a reason not to keep working as long as possible.  This of course isn't the case if you are military or  LEO and  rely on your rifle daily. Or if you don't have another rifle to  switch too. I have a hard time  replacing a barrel that isn't shot out, and  the amount of  ammo to get it to that  point  varies quite a bit.

100 consecutive 30 round mag dumps will basically ruin a barrel within an hour.

Roughly 14000 rounds on my Colt MT6400C barrel and able to hold 3 MOA with XM193 @100 when I put my SS 16x on there for shits n giggles.

Plus I neglect the crap outta that barrel/gun.

I have a Noveske barrel that I shoot very intermittently.   I'm talking maybe 60 rounds a year.  At that rate, this particular barrel will be around until approximately......



......August 18, 2490.

If you've got a squirt gun and wanna throw 3K rds downrange quickly, I don't think it'd really matter if it keyholed @ 100 yards.

No idea. I swapped out a bunch of Brls when the ban expired and I have so many carbines that none get shot that much.

I've got one Bushmaster with 7,542 rounds through it as of yesterday. Still shoots just fine.

In actual time the barrel is doing its part, guiding and spinning the bullet with the above round count, 40 seconds.

Haha Bingo.

So if a barrel was exposed to 40 continuous seconds of the same heat and pressure that it get's every time a bullet travels down it, it would be toast.

If that is true 40 seconds. That is an expensive barrel/second ratio..

The barrel is only working during the firing cycle from the time the primer ignites to when the bullet leaves the muzzle.  Within the span of 0.002 seconds, it endures up to 55,000 psi in the chamber, the heat and cutting flame of the burning powder, and the savagery imparted by the bullet's jacket along the rifling.  You take more time completing one blink of your eyes than it takes the bullet to go from 0 to Mach 3 down the short twisting metal tube.

It really is not that expensive, if you are truly getting in excess of 20,000 rounds before all the rifling is eroded from the bore.  The .223 is a very mild cartridge.  It is no where near as violent when compared to the really overbored calibers, ie. 22-250, 257 Wby.Mag, 7mm RemMag, or 300 Kong.

Not an expert here.
But i would think it would take FAR more than 20,000 rounds to completely erode the rifling of the bore.
I think the round counts that have been stated are when the throat of the barrel becomes so eroded
that it begins to noticeably affect usable accuracy and reliability.

Please correct me if i'm wrong or misunderstood

Throat erosion increases the freebore the bullet encounters as material from the barrel and chamber are removed from friction and heat.  All materials are susceptible to these forces, varied by construction and/or composition.   When the freebore increases, it affects the amount of space the bullet jumps from its concentric alignment within the cartridge to the rifling.  Within this space, the bullet does have a chance to yaw from the bore centerline every so slightly.  This can cause a small wobble in the flight of the projectile.  After this jump, the uniformity and condition of the rifling and the crown have a much greater affect on the balance of the projectile once it leaves the constraint of the bore.  

If you really want to know the condition of a barrel, you need a good magnifying bore scope, similar to the Hawkeye model from Gradient Lens Corporation.  If want to know what kind of unit you are starting with, use a borescope with a recording unit and/or printer to detect and report any major flaws in manufacturing before you even mount your new barrel on your rifle or in the lathe for profiling.  Most of the top barrel makers hand lap the bores for extremely smooth and consistent surfaces throughout the bore.  Cue the Lilja Rifle Barrels YouTube video to illustrate items to look for, and also from Hawkeye Borescopes.  Do take notice in the Hawkeye video at 1:42 showing heavy erosion and heat cracking.  That is an AR-15 barrel.  I personally had to wait an additional six months for a replacement .30 caliber barrel due to machining marks galling the grooves 12" in from the chamber end of the blank.

I know one shooter in Texas who competes on a regular basis at high power rifles matches out to 1000 yards matches with a .300WinMag using a Lothar Walther LW50 barrel.  He has in excess of 10,000 rounds through the tube, and that barrel will not die.  While he is missing about 10 inches of crisp rifling just past the chamber, the accuracy has still not degraded enough to replace it with the Krieger barrel sitting in his safe.  He is still able to hit one of the LaRue TG1 Targets consistently at 1000 yards.

I would suspect to the rate and amount of fire this platform can sustain, the heat cycles and temperature ranges will accelerate the degradation of the barrel life compared to a bolt action rifle of the same cartridge.  There are several videos when have been noted to show a FA weapon melting the barrel and other components in very quick order.  Take the same gun, reduce the rate of fire to shots per minute versus shots per second, and the barrel will not be affected as quickly, and have a longer service life.

This is my take
We have 20 us mil A1's
We shoot minimum 2000 rounds per week- 49 weeks a year.
Not counting the extra shooting per student every week....
Do the math. The colts are still going strong.
Springs are replaced , keys restaked , two bolts cracked , the barrels are still accurate.

Or a third of that if you're dumping at full-auto. (less than 10 minutes)

I shot out an LMT 10.5 inch barrel in less than 10,000 rounds by shooting 500-1,000 rounds a month. It was all suppressed and at rates of fire that routinely made my can visibly glow red in the daylight. In the process I bulged my gas tube, deformed a CAR single heat shield handguard, and eroded my suppressor mount to the point of requiring replacement before my suppressor would seat properly again. The throat and muzzle were so eroded that bullets were keyholing at 50 yards (without the can.) The barrel has long since been replaced but I am still railing on the original bolt, though I make it to the range with much less frequency now. Stupid job.  




Rob

Bigbore
Do you really like SS RRA barrels?
Ive been thinking long and hard going RRA SS but in a rifle length
It would be my First SS barrel on a AR15

Is that the same Wilson that makes the 1911's ?

That would be a "no".





Bill

I will say that my dad's colt hbar has somewhere between 20-30K rounds. I have been meaning to test it against my white oak high power build and lightly used Colt 6551 to see how it compares. My guess is at this point it is a 3 minute rifle, since my dad has ammo on hand that at one point in time shot 1 MOA, and it got 3 minutes when I tested it with that.





Also shooting from the bench, my groups with the colt 6551 and the white oak build (thank you very much for the trigger by the way) were about 1.5 MOA at 100 yards with the prvi partizan 75 grain. I attribute this to the fact I'm not that good at shooting. My high power scores have drastically increased, and every shot that doesn't hit the X ring can be easily attributed to me pulling the shot, or the wind changing direction. So, it is far more accurate than I am and gives me a good foundation to improve upon.





I would say that the answer to this question depends on quite a few things, including 1) skill of shooter, 2) distance at which you shoot and 3) the minimum acceptable accuracy to the shooter. This depends greatly on what the rifle is used for. For a carbine, yeah, I'd think every 20K rounds is fine.
 

As a high power shooter, influenced by a combination of high power shooting boards, local shooters and Bigbore, look into white oak armament. They make excellent barrels and are quite reasonable (same price or better than RRA for the most part). Adco sells both.



 

or rainier arms barrels

I've put 12,000 so far in my 6921 and it's still going strong!