ArizonaShooting.com

I purchased an AR awhile back and just got around to shooting it. It jammed every shot, which required me to knock the spent casing out of the rifle each time.
There is a noticeable ridge on the spent casing after extraction.

First things first.
Clean it.
Lube it.
Change ammo.
Change mag.

Failure to extract is a fairly common problem.
SOP is to get an extractor upgrade kit. Dirt cheap, easy to install, can't hurt, and often helps.
http://www.brownells.com/rifle-parts/extractor-parts/extractors/ar-15-m16-extractor-upgrade-kit-prod24635.aspx

Looks good to me. I might get one and I don't even have issues.

Is it chambered in 545 x 39 by chance?

Looks like a bad chamber to me.

I'd consider changing barrels.

D.

Good post on the worn barrel, chamber erosion? Have a lot of rounds been down the barrel?.. It sure looks like the case has been pushed further into the chamber????...,but it makes you wonder if this is even possible??.. If so, makes you wonder ?... Is there room for the for the extractor to even engage the spent shell?. Last question, new or reloaded ammo?....I've had a few of my reloads that wouldn't extract but it was that my small base sizing die wasn't set deep enough, although the round would pass in the case gauge...

This.. Looks like the chamber was cut wrong/bad reamer..

I would check that out first.

The ring seems to be right about where a 5.56 would hit in a 545x39 gun. Forward assist or HEAVY spring might close bolt enough to fire in partial battery.

Improperly reamed...has a ridge. If that barrel was sold I wonder how the hell they test fired the weapon before boxing and shipping?

D.

YUP!!!, bad ju-ju in that chamber,... either bad reaming or wrong caliber stamped on the barrel, hard to tell from a pic.

Is this an AR BUILD,... are you shooting reloads?
There are a lot of avenues to consider.

I wouldn't shoot that again, until I figured it all out.

Can't tell by the picture but you might be able to take a good reamer and give it a couple quick light turns to remove enough of that ring to make it work.

Makes me wonder if it was even test fired in the first place. Otherwise it should not have left the factory. Further reaming may not resolve the issue. Best to have a competent gunsmith take a look at it first before proceeding any further. And be sure to take some of the extracted cases with you for the 'smith to look at.

Snake oil IMO. Can't tell you how many thousands of rounds I've run through and AR and have yet to install an extractor upgrade kit.

Any results, resolution?

It would be interesting to learn the actual diagnosis and repair.