Setup:  RRA 9mm upper, Colt mags, Hahn block, 9mm buffer

I'm getting failures to fully eject that seem to be magazine dependent.  It doesn't seem like these two things should be related...  

The spent brass is extracted fully from the chamber 100% of the time but the cases aren't clearing the ejection port.  The next round is being chambered 100% no problem but the spent brass just jumbles around in there causing the bolt to jam up.  I have 5 Colt 20rd mags, 3 work, 2 repeatedly cause this ejection problem.

This is a mystery to me.... how can ejection be mag related?

need some help
thanks

C'mon guys, I need some help from the 9mm guru's here.  Going to the range tomorrow and I'd like to get this thing runnin' like a top.

Thanks in advance for your help

The 2 mags could be allowing the rounds in the mag to hit the spent casing during ejection.  Might have to carefully bend the feed lips down a little or make the mag catch slot a little wider so the mag drops.  Hard to tell without seeing it.  

Before you start fiddling with the mags, check your extractor.  RRA's are know to use a piece of crap extractor pin which can work itself loose.  The extracted case could be slipping down the face of the bolt and contacting the new cartridge, as Joe says.  Maybe.

FTE in the Colt system is usually the extractor, just like Beo says, bad pin, and/or weak tension.

DO NOT start bending your mags or cutting on your slot.  Colts are pretty consistant, I have yet to see defective feed lips or catch location.

Quoted: .  I have 5 Colt 20rd mags, 3 work, 2 repeatedly cause this ejection problem.

Then you have 2 bad mags I would think ..
I have 2 Pre-Ban Colt's that have never missed a beat until i bought 5 of the new 32 round Colt mags that are out now ...... 3 were bad .. Double feed like crazy
As the carrier traveled back at the point of ejection a new round would jump up , instead of the carrier stripping a new round  ... thus causing a jam like you described

I always suspected that at least some jams were being caused by the magazine releasing a round early.  We all know that Colt mags are prone to "fountain" the rounds if dropped and it seems that if the feed lips aren't exactly right then a round will pop out and foul the ejection of the spent casing.  Short of a high speed video camera set-up I don't know how to prove this, but it would explain a failure to eject that is distinctly magazine related.

Quoted: I always suspected that at least some jams were being caused by the magazine releasing a round early.  We all know that Colt mags are prone to "fountain" the rounds if dropped and it seems that if the feed lips aren't exactly right then a round will pop out and foul the ejection of the spent casing.  Short of a high speed video camera set-up I don't know how to prove this, but it would explain a failure to eject that is distinctly magazine related.

Your right in that there would be no way to tell for sure without a high speed camera, but I don’t think that’s what’s happening.  If the extractor is doing its job correctly then the empty case is hitting the ejector before the bolt clears the next round in the magazine.  As well, if the round is popping out of the magazine with any regularity I would expect to at least occasionally find a live round in the gun (the last round in the magazine) with the bolt locked back.

Thanks everyone for troubleshootin' this for me. (Bad Pun Intended).

I got to agree with Beowulf as I have never had any actual double feeds (two LIVE rounds heading toward chamber).  Its always just the extracted empty case that causes the jam.  Also the next live round is always chambered correctly.

It's the empty brass thats garbling up the bolt.

Seems like it would have to be ejector related; the angle, position, not sure....

Another possibility for your FTEs is this:  I was running low powered ammo (Federal 124gr NT), and would get failures to eject every 5-10rds.  I have been running my own reloads now, nothing hot, just 124gr West Coast copper plated round nose over 4.1gr Titegroup.  No FTEs.

I also had noticed my ejector had gotten out of tune as others have posted, fixed that right up, no problem with that, either!  

Quoted: I also had noticed my ejector had gotten out of tune as others have posted, fixed that right up, no problem with that, either!

Can you give anymore details....  What work did you do to your ejector to fix the problem?

I'm shooting 115gr Blazer BRASS(No aluminum stuff so no torn rims).  Should I try switching to a lighter M4 buffer rather than the 9mm buffer?

thanks again all.

Quoted: I'm shooting 115gr Blazer BRASS(No aluminum stuff so no torn rims).  Should I try switching to a lighter M4 buffer rather than the 9mm buffer? thanks again all.

Probably not, since a buffer problem would most likely show with all of your mags.

Try some Winchester white box. I have had problems in the past with Remington stuff not enought power in the stuff to work the action all the way. IF that does not fix it check the bolt for the extractor retaining pin and see if it coming out.

Well after messing with this thing for a while I decided to pull the extractor out and give it a bit more tension.  Went to the range today and had only one failure in 300rds.  So for now I consider this problem solved.  I still don't understand how the problem could have been with the extractor but only showed up with certain mags.  Seems like that would have effected all mags equally.

Thanks all for your help.  This thing is a blast to shoot now that it runs!

The extractor is undoubtedly the primary source of these stoppages.  Sometimes the pin moves and no longer holds it in place.  Sometimes the space behind the hook is a bit too small and a round with a slightly thicker rim will not be caught under the hook.  Sometimes there is a buildup of fouling in the extractor hole and it loses tension.

It still doesn't explain failures to eject that are directly tied to specific magazines.  I mark all my mags so I can track problematic ones and I had some of the South African 40-round modified UZI mags that I wanted to use in competition but couldn't because they weren't reliable enough.  I turned them over to a very talented (but incredibly anal) tool & die man, who reworked the feed lips and the mag catch slot.  Now they feed and function perfectly and I haven't had a mag-related stoppage in years.  He says that the distance between the feed lips is absolutely critical and being only a few hundreds of an inch off will cause problems.

I gotta go with what works.

I have the same setup (RRA upper, Hahn block, 9mm buffer), and I had the same problem yesterday. I'll fiddle with the extractor a bit...

Quoted: Try some Winchester white box. I have had problems in the past with Remington stuff not enought power in the stuff to work the action all the way. IF that does not fix it check the bolt for the extractor retaining pin and see if it coming out.

+1 UMC will not cycle in mine.  Neither will aluminum cased blazer, but everything else will.