What causes a double feed?

[JSThane]

Are you -sure- the extractor isn't damaged, or has dirt under it? If it doesn't, I'd look long and hard at the profile of the case rims. See if there's a difference in the shape of the extraction groove on the rounds that failed to eject. From what you describe, the extractor is "jumping" back off the rim on the cycle, leaving the spent round stuck in the chamber. A broken/chipped extractor tooth, excessive carbon buildup under the extractor, or improperly shaped extraction grooves on the cases, seems to be the most likely culprits to me.

Another possibility too is a dirty chamber. If you've shot Wolf or other steel-cased ammo recently, you may have some of their nastiness built up in your chamber. I went through this with one of my ARs, and practically had to chuck a brass chamber brush up in my drill to clean out the laquer and crud left by the Wolf ammo (relax guys, I didn't really do that! LOTS of scrubbing by hand, tho').

So, in order, I'd look at the extractor, look for dirt buildup under the extractor, look at your fired cases, and look inside the chamber.

[Shoot_First]

As noted several times, we've had numerous requests to to make some changes to help those who read the Forum on mobile devices. These changes included smaller photos in signature lines, as well as a limit on the number of lines in a signature line. Most people have complied with the signature line rule and we appreciate your efforts. However, a number of Members are still using signatures that exceed the 4 line limit. A few have simply used a very long sentence that wraps to multiple lines.

For several months, we have requested that Members comply with the signature line rule, but because of the time/effort required to enforce the rule, we've relied primarily on voluntary compliance. We've had complaints from Members about the perceived lack of uniform enforcement and these complaints have some merit. Still other Members have complained that the lack of compliance is still creating problems when they read the Forum using a mobile device.

To deal with these issues, we will begin active enforcement of the 4-line limit. Due to differences in screen resolution, we are also limiting lines to 80 characters and blank lines will be counted. As previously mentioned, it takes a fair amount of time and effort for us to access a Member's profile and delete everything over 4 lines. If we are forced to do this, we are just going to delete the entire signature line. This may irritate some folks but look at it this way. A Member only has to do this once, but we have to do it many dozens of times. Please take care of this issue yourself and help your fellow Members who read the Forum using mobile devices.

Thanks,
Chas.

Kevin, Your signature has 6 lines.