Question about barrels...

B_Mc

How do you know when you barrel is shot???

iwannausername

All depends on the gun, the round, and what you use it for.

I figured my Mini 14 barrel was a goner when bullets were leaving perfect keyholes at 10 paces. I could handle 5" groups at 100 yards, but not totally missing the berm...

If you are shooting one of those super accurate bench guns, it may be when your old favorite load no longer groups under .25" at 100 yards.

Most likely somewhere between the two though...

RCrosby

+1 on the above.
Also, assuming an unacceptable fall in performance, make sure barrel is thoroughly and properly cleaned and that there are no other factors accounting for the loss of accuracy: i.e. scope, mounting, bedding, etc.
Also if the throat is noticably eroded, you may buy some time by seating your bullets out a bit further. Like the man said, your previous level of performance and needs are critical. I've had some barrels that had bad throats and pitted bores (handguns here) and yet gave acceptable (for me) accuracy in the neighborhood of 2" groups at 25 yards. They required frequent cleaning, but were certainly reasonable.

Emmett Dunham

Take a gauge and check the muzzel wear, you can also check the chamber and last headspace the rifle. I have a M1 Garand that swallows the ME gauge and It still shoots ok!


Emmett

JustC

The best way to determine that is with a bore scope. Or,..without that, you'll notice when it starts to lose the accuracy you have come to expect. This takes several thousand rounds unless you are running it very hot on a regular basis.