SRM and RN-Submariner are both right.

Realistically, I would say that they can die at any time.
Many factors are involved in barrel life and it's all down to what goes down the barrel.
Your cleaning regime plays a factor in this as cleaning causes wear too.

Heavy bullets will help to wear out a barrel faster than lighter ones. Especially bullets in the 75-80gn range.

I had a 14.5" barrel of dubious quality that died completety at 5100rds and I mean that for no reason it started to throw bullets sideways. (62gn RG that is, it still shot tiny little knots with lighter heads}
I have a pic somewhere. I posted it before.
I also had a Douglas stainless that I killed by using LRP mags and 80gn SMK's. (It's the heat that does it, not friction).
I had another Douglas that fell off at 6600rds.
It can be a gradual thing and doesn't show up until long range, where your groups start to open up.

I've seen barrels with the first 2-4" of rifling smoothbored that still shot OK at 2-300yds, but beyond that....forget it.

Giiven the types of bullets you are shooting and the distances you are shooting at, I wouldn't worry about it for some time yet. I would think your gun will be good for -5500-8000rds.

It could go longer or it could die sooner. You just never know.

Mark

OK,
Here's a pic I took (it was difficult because of the reflection) of the carbine barrel that died @5300 rds.
I've sectioned the chamber and first part of the barrel because I was curious to see what was going on.

As you can see, it's pretty well worn out and although it looks like there's rifling all the way from the throat, that actually isn't the case.
What appears to be rifling is actually lines of erosion rubbing along the edges of what use to be the lands. It is actually smooth to the touch and you can't even feel it with your fingernail.

As I said, this barrel stopped shooting 62gn RG bullets completely. (it would throw them sideways at 100yds) but would still shoot lighter varmint bullets with fantastic accuracy.
I took it off the gun a week later and cut it up.

ACR and Matt's barrels did exactly the same thing. It was just like switching them off. There was no deterioration....they just stopped shooting.


Here are some pics of what was happening
This is a perfect example of a tumbling bullet


Here you can see just how far away from group centre these two unstable bullets landed.


There are more like these but you get the idea.

As I was saying, the barrel continued to shoot lighter bullets with unerring accuracy, as you can see in the pics below




Mark

Quoted: Mine's done about 8.5k and is still hits pretty well at 600 but it's due for a change. It definately isn't as good as it used to be and I get the odd unexpected miss that should have been a solid hit, but it's still useable. Apart form the first 2000 or so rounds of 69 grain the rest has been 77grainers.  I just can't trust it anymore and that means it's got to go.

Sooooo.....

Quoted: Quoted: Sooooo..... Well, If those people that RNsubmariner loves so much  don't send me an aditional bill for a recent arrival, I think we'll be having a little chat soon.

I'm here.....[cough] for the post count, naturally.... [/cough]

Seriously though, I still have some of those fancy blanks, if you're still interested!

nb: they won't be around forever

Quoted: Quoted: I'll try and find out how  many rounds mod armourers think it takes to wreck a barrel and post later. They are chrome lined, so thousands of rounds, the L85 is not touched until it doesn't gauge correctly, or never as they are a real bitch to barrel change! The upper flexes and bends unless you are very careful

US Army specs state that a M4 Chrome lined barrel has a lifespan of 9600rds

Mark