Shot out my 5.45mm S&W AR15's barrel

[liaisons]

That's some nice keyholeing you got there..!

Curious... are the S&W 5.45 barrels chrome lined?

[VMI-MO]

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.

It wasnt ammo.

Several types were tried through the suspect upper with the same results.

The same ammo was fired through another 5.45 upper and it didnt key hole.

PJ

[Littlelebowski]

Curious... are the S&W 5.45 barrels chrome lined?

Yes, they are.

[ohiorifleman]

Congratulations- I am sure you are appreciating the milestone as much as I would. It would be great if S&W would replace the barrel but since you've saved about 2400.00 shooting this over brass .223 a barrel is small potatoes.
Buying a rifle to look cool on this forum- 800.00 to 2500.00, Actually wearing one out through use- Priceless

[crossgun]

When mine goes I am going to replace it with a barrel from Ballistic Advantage. Their barrel is melonited and I have become a big fan of that finish. I should do really well with the corrosive surplus ammo.

http://ballisticadvantagellc.com/545x39.php

[Robb Jensen]

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.

I'd recommend bringing it in and I'll remove it for you, if it's perm. attached I can remove it and or test fire it for you.
Many times with ARs you'll get a carbon wall inside the flash hider/brake that the projectiles impact after leaving the barrels crown. 99% of the time you can't see it from the muzzle end of the flash hider or brake unless you remove the flash hider or brake from the barrel.

Most likely the Copper Killer won't remove the wall of carbon in that area. This is the reason why I try to discourage people from perm. attaching devices on 14.5" barrels.

[Heavy Metal]

I am begining to wonder if carbon under the FH is the culprit in 'Fleet Yaw'.

[Robb Jensen]

I am begining to wonder if carbon under the FH is the culprit in 'Fleet Yaw'.

In my line of work this is the problem about 98% of the time.

[30 cal slut]

In my line of work this is the problem about 98% of the time.

I hope so. I'm coming up on 12K rounds pretty soon.

[mvelimir]

If that turns out to be the case, then I think I got it pretty close suggesting to re-crown the muzzle. That kind of keyholing can only be made be something at the muzzle end.