Everything is keyholing. At least Sov surplus and 60 grain Silver Bear. Probably about 12k rds through it. Going to call S&W Monday but I expect to pay for rebarreling it.
Cool how long did it take for you to notice it was tumbling. More or less what I am asking did it happen all of sudden or was it more of a progressive thing.
I think that it happened sort of quickly. Haven’t shot it on paper for a while. I did notice it wasn’t performing to its normal level of accuracy though.
what range was that at?
hey L.L.
how many rds do u have down range
been reading ur posts since u started on this caliber
i have 3 of them
10-1/2" has about 5ooo rds
16" has about 1ooo rds
othjer 1 never shot it.
if u have not shot a ton it does not seem possible but u have been shooting as long as i have on mine
pls post when u get an answer
tks
At what distance was that happening?
I was shooting my AR with S&W upper as well as newly purchased AK-74 yesterday for the first time, using Silver Bear ammo. I was only testing for function and shot at 25 and 50 yards, but all the holes were round and clear. I will imagine that keyholing will appear at longer distance, but then - I wouldn’t know because my experience with this particular ammo is at 120 rounds fired yesterday and that’s it.
I made a post with some photos under "I am taking the 5.45x39mm plunge! updated 09-23-09 " https://www.m4carbine.net/showthread.php?t=18015&page=40
25, 50, and 100 yards.
As I said in my first post, I have about 12k rds through it.
Well, if it is doing it at 25 yards and you have 12k rounds through it, I’ll try to re-crown the muzzle. That might be a quick and easy fix.
I am going to see what GotM4 says.
Yeah, that seems more like damage than a shot out barrel.
My limited experience with shot-out barrels is that it happens all of a sudden, I mean, they don’t start keyholing a little and the gradually get worse-- they go from OK to keyholing over a short number of rounds.
I think 12K is “got your money’s worth” in this caliber (or 5.56 for that matter).
I think it might be the ammo. The core in moving within the jacket. That has been my experience as I have seen it come and go.
Try some different ammo just to confirm if you havent already.
What kind of firing schedule has the barrel seen?
This brings up a question I’ve long been curious about. What is the actual expected barrel life rule of thumb? My understanding was expect group sizes to double by 5k, nearly useless by 10k.
I ask because I’ve read multiple accounts of barrels with 12k, 16k or other ridiculous numbers on them. Not that I doubt the numbers, I just thought the barrels would be useless by then.
I have had a SureFire muzzle brake on it for sometime. Don’t think that it is damaged.
See the first post in this thread.
I recommend shooting it w/o any muzzle device after cleaning the crown to see if its just a very dirty crown and brake/flash hider.
Yea I try this… Easy enough to do, no more cost than a normal trip to the range…
Hows it look according to a visual inspection??? Crown and throat end?
So it is written, so it shall be done 
If you have the time, mind PMing me the best way to remove that SureFire brake?
Cleaning it with Montana Copper Killer today.
so whats the barrel life expectancy on a regular AR ?
lets say shooting Wolf through a 6920 ?
I cant say Ive ever really thought about it much, didnt shoot much AR’s until this past year or so, but 12k doesnt seem like a lot of rounds. I prob shoot 8-10k+ a year in 45 through my 1911 just with weekly 100-200 round practices, plus one or two competitions a month through the spring/summer/fall and a few classes (actually trying to move to more in a 9mm 1911 this year for regular practice’s and cut the 45 consumption in half). I imagine if you shot your AR mainly with the focus I put on pistol you would kill a barrel every year to year and half… ouch.