I hardly have this RR upper broken in with only about 350 rounds through it.

Occasionally, maybe five times total, I have  gotten a stovepipe jam with a loaded round halfway into the chamber and the empty case stuck over it between the bolt and the partially loaded round.  

The empty case always ends up with the case head sticking out and the case mouth crushed inside the receiver.

There is a good firm ding from the ejector on the case rim and when functioning normally the upper throws the empties about six feet out.

Ammo has been a mix of 147gr subsonic handloads and 115gr WalMart Winchester.

Has anyone else experienced this?  Fixed it?
Thanks.
Mario_FAMOInc.  

I had similar problems, but did'nt have the positive ejector marks on the cases that did'nt eject. For awhile I thought some cases were hitting the upper on the way out and staying in there.

Mine turned out to be long headspace and the extractor was'nt hooking the rim on some cases. They just blew back out of the chamber and layed there getting crunched by the carrier when it picked up the next round. All fixed now with the help of a board member.

With good ejector marks on the cases I'd say your extractor has a good hold on your empty. Hopefully someone else can comeup with a cure.

My POS RRA does the same damn thing.
I have sent it to RRA once. They said they fixed
it and it work fine for them. Bullshit, thing still jams.

Then I sent it off to a Gunsmith to see what he could do.
Had them bevel my feed ramp. Works better, but still jams.

Sent it back and now they are ramping my bolt.
Should have the POS back this week for it to disappoint me again.
Wish I never bought the damn thing.

 The round comes out of the mag, hits the feed ramp, then hits the small chamfer on the barrel prior to going into the chamber and flings up.  You need to "throat" the bottom of the chamber a little. This allows the feed ramp to guide the bullet in the chamber without hitting the barrel.  The head space being incorrect, or the mags sitting to high can cause incorrect ejecting.

If you have correctly converted mags or Colt mags, a feed block adjusted so the ejector is almost rubbing the bolt, the ejector bent to the right so it's almost rubbing the bolt, throat your barrel, and check the head space, I guarantee you 100% these 9mm uppers run. I can post pics tonight if anyone wants to see them.


50rnd dump of silver bear 147gr video of my M16 6" upper I made(was RRA 16")with UZI coastal can ,and ASA mag well adapter, I don't know the ugly over weight guy....

[url]http://users.zoominternet.net/~picplace/m169mmdrum.mov[/url]

Added pictures of mag well adapter and the throated barrel.  

Questions or want this done [email][email protected][/email]

[img]http://users.zoominternet.net/~picplace/9mmmagwell.JPG[/img]


[img]http://users.zoominternet.net/~picplace/9mmbarrelthroat.JPG[/img]

Thanks guys.
I am way too tired tonight to get out the upper to check all of these things, but I'll try tomorrow night.
Mario

My shooting buddy came to my work today to tune his 9mm M16 upper.  He was getting a new round trying to get in the chamber and a spent case stuck on top of the new round.  

So, I sprayed blue layout ink on the cases of a few new rounds.  Then we shot a couple of rounds. It jammed. The layout die reviled that the extractor wasn't going into the extraction slot on the case deep enough.  I ground .005/.007" of the bolt face and it ran 100%.


For you guys that have intermittent ejection problems, it might be as simple as the dirt build up between the bolt face and the barrel causing the ejector to not go deep enough in the case groove.... I'd mill or grind a little off the bolt face to counteract the dirt build up.

A awesome running 9mm upper can make you look like this guy!!

[img]http://images.usatoday.com/news/healthscience/health/_photos/2002-04-18-inside-enzyte.jpg[/img]

Stupid chambers being cut a bit deep!! Every body says that as long as the bolt is closed, the headspace is correct--- BS.

My bolt is .125" from the face to the face where case sits... and the case was sticking .100" out out the chamber...OOOPPPS, .025 excess headspace, fire pin energy was used to cover the gap, what was left would not fire the primer.

I had barrel face cut to have case sticking out .130" +/-, and had to cut the extension ring also to set the barrel back into the upper. Now I have a slight air gap from bolt face to barrel face when there is a round in the chamber, dirt wont affect, as it build, bolt squeezes it out.

Kinda watch out removing material from the bolt  face, as extractor top is very close also.  

joeblack did an excellent job of ironing out the wrinkles in my 9mm upper. the grooves in the magblock are just right to feed Wolf JHP 147gr ammo as well as 115gr white-box winchester. as he mentioned, he also took a bit off the bolt-face to allow a better "grab" on the rim by the extractor. he does excellent work, and rapid turn-around.
you won't regret having him work on your weapon.  
 my .02 worth.
   Harry

Guys,
My problem sounds more like the extractor thing joeblack is talking about, feeding itself has not been a problem.  After examining case rims again it looks like the extractor is grasping a bit back on the rim.

I have noticed a very slight bulge around the head of the case on extracted rounds, but it looks like "normal" blowback action swelling, not a real headspace problem.

I'll have to get on this tomorrow, it is my only night off for the week.

Mario

Yes you have to do the barrel retaining ring too or it'll bugger up your buffer retaining pin. I know!

I went out today to the range with the 9mm RR upper again.  This time I took 50 rounds of mixed ammo with black perminate marker slathered on the rims.  

What I found was that the extractor was going completely to the bottom of the rim with all makes of cases with the exception of 2 R-P cases.  Several other R-P cases showed the extractor had gotton to the bottom of the rim o.k. .  Even the cases that weren't being thrown as far from the gun had good extraction marks.  

I had to do all of my shooting on semi auto due to the range rules and as you might suspect, I had none of the stovepipe jams that previously occurred.  I was even using the aftermarket mag that I suspected of being part of the problem.

So the problem appears to be full auto related and with all else being equal (I have the 2 piece 9mm buffer installed) I think that I am still looking at a mag related problem in spite of the good function today on semi.

What do you think?

Thanks,
Mario      

Some ideas:

Be sure your ejector is bent horizontally and vertically so it almost touches the bolt. Blue the ejector and you know you are close when the blueing is rubbed off! The closer to the bolt the better ejecting is.  Be sure the end of the ejector is ground perpendicular to the spent case.  Ejectors are stamped and never de burred, so, yours might be angular instead of flat.

Poorly converted mags that are too high would have the rounds in the mag acting like the ejector. But you are only seeing a few bad rounds, so, I think unlikely. Mags too low would cause the round to hit the feed ramp and the barrel face and most likely cause the stovepipe......

You mentioned you didn't have any stove pipe jams.  Using a Colt style clamping block?  If so, you got lucky and set it correctly.  I hate them, they do not repeat to my satisfaction.  A beautiful phrase I heard while shooting with my FFL/SOT was "wow the ASA was worth all the money I    paid....this was the second time I inserted the mag well adapter and the M16 ran with out issue"  ASA mag well adapter and a throated barrel is awesome.  72 round Vector drum dumps without issues!!

A another reason for grinding .005 to .010 off the face of your bolt is as the barrel and bolt face gets dirty, the head space changes and extraction becomes a issue. [b]Remember just because you have marks in the case rims it doesn't mean that there is enough slop. .001 clearance and it extracts. -.001 and it doesn't.  I would take some off the bolt face.[/b]

I use Main Cart. 147gr, Silver Bear 145 gr JHP, Wally Mart 115gr. All seem the same but the Wally Mart is sonic.  Stay away from what doesn't work?


Don't know if anything helped......

Mag well block is by VM Hy Tech and the mags are a mix of Uzi mags (IMI/SA/AA & aftermarket).

The ejector rubs along the side of the bolt and is only a few thousanths from rubbing the underside.  The front is cleanly square and perpendicular to the case.

For what it's worth, I'm still working on this project but it is on hold for now until I get my barrel back from having it cut down to 10-1/2".  

I figured as long as I had the barrel out of the receiver to open up the feed channel I would send it out to have it chopped.

To be continued...

Another thing to look at:


I've worked on another 9mm Upper.  The extractor had a burr on the edge that engages the rim of the cartridge case.  I set up a surface grinder with a .062 wide Borzon wheel and ground the burr off and continued to grind .004 more so the entire surface cleaned up. Now spinning the cartridge while in the bolt, the extractor rubs a mark in the cartridge groove. So, it shows the extractor is fully engaged. The burr didn't allow full engagement....