Barrel life Chrome lined 556 Nato

[vaguru]

Just curious about barrel life in a Colt chrome lined 1/7 Nato 5.56 barrel. I have a HB that has 7800 rounds through it, used in NRA Service rifle competition. It now has a throat that has moved .675" from where it was new, that's a lot of free bore. Still shoots some loads well, others not so good, and velocity has dropped off considerably.

So just curious how many rounds a chrome lined barrel should last or your experience with them.

BTW, that barrel was replaced with a Kreiger HB.

[imaguy3]

it depends on how it's treated over its life with regards to firing schedule (mag dumps and high volume hot barrel shooting, or slow cool barrel target shooting)...

It also depends on your definition of acceptable accuracy is. A barrel that starts at 1/2moa may be unacceptable to someone once it gets to 3/4moa.. but still good to someone else at 1.5moa groups.

I have read anywhere north of 10k is pretty standard... but I wouldn't be unhappy with 7800 either.

[Old Bob]

My original AR15 had a 1/7 Colt HBAR chrome-lined barrel. Never did a round count on it but would guess it was way north of 7800 just by the 1000 round cases purchased & ammo reloaded. Used it for service rifle matches to begin with but then used it for 3 gun matches. After about 7 years or so it started shooting patterns instead of groups. Replaced it with a stainless steel 1/8 Wilson Combat 20" .223 Wylde barrel.

[LR1955]

My original AR15 had a 1/7 Colt HBAR chrome-lined barrel. Never did a round count on it but would guess it was way north of 7800 just by the 1000 round cases purchased & ammo reloaded. Used it for service rifle matches to begin with but then used it for 3 gun matches. After about 7 years or so it started shooting patterns instead of groups. Replaced it with a stainless steel 1/8 Wilson Combat 20" .223 Wylde barrel.

OB:

From what I recall, the chrome lining was put in because it held up better and had less malfunctions under combat conditions. I would think that for High Power you could get at least 10K rounds with a 5.56 before a new barrel was needed. 7K was kind of the standard with 7.62 but guys who had quality barrels and didn't do ammo burns would often say they had 10K or more and the barrel still held X rings. Often they would just go to a longer bullet when things started getting flaky. That really does work when throats get eroded.

I once looked into the bore of a M-24 that had never been gauged for ten years and about two inches of the rifling was completely gone at the throat. I still held a E Sil at 1K and that was shooting M-118 SB. Funny what firearms can take and still perform really well.

Three gun? Not really sure but a lot less than 7K in my opinion. That is some serious rapid fire without a lot of time to cool.

LR-55

[Old Bob]

The rifle was used when I bought it so I have no idea the round count before I had it. I've been trying to estimate my round count during the nearly 12 years the original Colt barrel was installed. Combining factory ammo purchased plus the couple of thousand reloads I put through it, my best guess is 11 to 12K. I was shootin' that gun a lot! Replaced two 1911 barrels in the same time frame. Replaced the gas seals in my Rem 1100 a few times as well.

Yeah, the throat on that old Colt barrel was pretty much trashed ... Seemed like it went bad from one week to the next. During a Sunday practice session everything seemed fine. The next Saturday, during a regular bi-monthly match, it all went south. Was missing a lot of steel, winging no-shoots & shooting crappy scores. Shot on paper after the match ... nothing but patterns! I thought maybe my ACOG crapped out. Took it home a switched scopes (a new, never mounted PA1x6 LPVO) & returned to the range the next week. Dang! I couldn't get the scope to zero worth a damn. Back home I pulled the barrel to find the trashed throat. The new WC barrel shoots great, but, since both knees gave out on me, I don't shoot 3 gun anymore.

[montana]

You can keep track of your barrel life with a muzzle erosion and chamber erosion gauges..I use them with all my new 5.56 barrels to keep track of the wear.
One of the worse things a person can do is over tighten a muzzle devise. The more torque applied to the muzzle device, the more the barrel will compress under the muzzle device. This also applies to gas blocks when over tightening set screws, clamp types and pins.

[vaguru]

Playing with powder charges in the above mentioned barrel to determine if it will keep shooting well. By varying charges with the loads that were not so good, managed to shoot under 1" at 100 yds. I now have this barrel shooting 3 different loads under 1" with the best so far at .640". Very pleased with the results, and good enough for the varmint hunting I plan to use it for.


Thanks for all replies.

[VASCAR2]

Thanks for the update vaguru!