The casings might be getting stuck a little in the chamber.

1) make sure the flutes are clean... get in there with a light and have a look.
2) were you using steel cased ammo? while many have shot steel cased sucessfully, there are plenty that would say not to, for good reason.
3) you could have a bad extractor spring or worn extractor.

 

Winchester and federal sp ammo has the same problem. A few rounds eject then one will either not eject all the way or casing will stove pipe. I cleaned chamber good befor firing? Also I have noticed cycling the rifle by hand sometimes unfired rounds will not fully eject? I guess I could try replacing with surplus gs extractor and spring? How hard is it to take bolt head apart and replace exctractor? Any change the recoil spring on stock needs replacing also?

 

clean chamber, change magazine, change ammo. next would be extractor and springs, check headspace.

 

Headspace is good, Extractor and spring looks good and cleaned. I did notice the bolt block is not factory ib like rest of gun. It has a small star and marked 8/61. It still lokks good no real wear. Could this be the problem? Should I try replacing it?

 

you have a rheinmetall bolt carrier,which is as good as they get. Its not the carrier thats causing this. Is the extractor good and tight? There should be no movement with finger pressure. what brand of mag were you using? Also,make sure the locking lever on the carrier is Tight also. Make sure its clean in flutes and on the barrel/chamber face area where the bolt head slams into when firing. Make sure your rollers are functioning properly. Hope you figure it out. Let us know

 

Yeah I can move with finger pressure. I believe I will try replacing it with extractor and extractor spring (used hk) from centerfire next week. Could it haVE SIMPLy WORE OUT FROM USE? Were the Hk-91 series built brand new or werer some surplushk parts used? I have decided to definetly keep the gun. I regret selling my prior 91 and 93. I jusat donr believe any others measure up to the 90 series hk.
Anyone had good luck with the centerfire hk parts?

 

Before replacing any parts, test some known good ammunition. Portuguese (FNM or BP) or German (DAG, etc) military surplus would be a good choice.

Is this an H&K factory-built HK91? I've never heard of an H&K factory rifle that had a Rheinmetall bolt carrier.

Ejection problems very often are due to poor fit between the trigger group and the receiver. Is there any vertical play between the receiver and "lower" / grip frame?

 

Do not put used extractor or spring in this rifle. There are new parts from RTG that are fairly cheap. The STAR w/date is a rheinmetall carrier. It may have been swapped over time. AGC is right about checking snugness on the lower to upper fit. Is the lower matching to the rifle? let us know, we want to see your rifle up and running correctly bro. RTG parts is where to buy these parts. And NO,they did not use surplus parts on brand new factory HK91 rifles.

 

Took apart ejector today. It was caked with residue buildup underneath ejector. After cleaning I fired about 20rds through gun. I had 4 failures in the 20rds and I found out what was happening. After firing the ejector did not release casing, causing the bolt with casing still attached to either jam up with the next round, wedge in barrel with live round. I took the bolt carrier pin and spring out and noticed the spring was very weak. I could compress it with little to no effort between my fingers. Also after reassemply I noticed it took very little pressure to compree it to unlock rollers. Could this be my problem? As I said the gun funtioned great most of the time. Iused silver bear and winchester power point today.

 

you lost me on the bolt carrier"pin& spring" . Which spring? the locking lever on the carrier. Pics would help if your not sure about proper terms for parts on these rifles.

 

And yes fit is tight and rifle is an ib datecoded on all parts except for bolt carrier.

 

Yes the locking lever on carrier.

 

Now I'm not sure if any factory HK91 rifles used a Rheinmetal carrier, but plenty of factory G3 rifles where manufactured using Rheinmetall carriers. As far as I know, all Rheinmetal carriers are F/A carriers, so my guess is that somebody wanted the option to use this rifle as a sear host. TCR39 is correct in saying that this should not cause any problem at all.

I would suggest that you drop the mag and clear then weapon. Then while pulling the cocking handle back very slowly, look through the ejection port at the face of the bolt heat. You should see the ejector lever riding through the slot in the bolt head. It should be coming through as high as possible. If it is low, then it's probably missing the back of the casing. I agree with TCR about NOT using a surplus ejector lever or spring as these parts can be had brand new fairly cheaply.

 

Checked ejector seem to be fine (almost touching metal on bolt head when it runs through). I then hand cycled a 20rd mag with no issues? Is it possible the recoil spring in the stock could be weak and causing bolt not to return all the way. As I say it only fells to eject evr 4 or 5rds?

 

The locking lever needs to be TIGHT, if its that weak ;it will unlock to fast. And could be unsafe I suspect also.
Ejector and Extractor are two different issues. DID YOU replace the extractor with a new one &spring first? Then make sure lower is not moving around either. Check DEM flutes bro. Dental pick if need be,if you werent properly cleaning through the years till NOW. I,m sure you have some less than clean flutes. Get in there.I use a mag light to look right in there. Hopefully its something simple. Imost tell you that my century G-3 years ago did this until I took the ejector spring out from under the back of ejector. It looks like a ball point pen spring. It never jammed again.Springs a $1 bro. If that spring is binding,it will surely stop the front end from coming up high enough to EJECT [not extract] the casing from weapon.Extractor pulls casing from chamber.Ejector kicks it out.

 

Any ideas why the problem only shows up every few shots instead of doing this every shot? A friend shot a few rounds of federal cheap ammo today and said he had no problems.

 

The locking lever and spring sound like they're part of the problem. The locking lever should be nearly impossible to move with finger pressure. There's actually a tool made to compress the lever and spring to allow the pin to be inserted.

But that shouldn't be (directly) affecting the ejection...

From the description of the fired cases being extracted from the chamber but not ejected, I would suspect the extractor and extractor spring; most likely the spring. The case is not being held tightly enough for the ejector to give it a proper kick out of the receiver.

RTG wants $17 for a new extractor and spring:

http://robertrtg.com/g3rollerext.html

Replace both to be sure. Removing and reinstalling the extractor takes less than a minute.

RTG also has the locking lever parts:

http://robertrtg.com/g3lockinglever.html

If your locking lever looks OK it's probably usable. But it does sound like there's something wrong with the spring if you're able to easily move it. Replacing it will require either the locking lever spring tool (I think PTR sells them, for around $25?), a suitably padded vise, or about six hands to hold everything in place and compress the spring and lever while driving the pin.

The Rheinmetall bolt carrier does suggest the rifle was used as a sear host at some point. Could it have been reassembled with the wrong ejector in the trigger pack? A 7.62mm NATO ejector should be almost exactly 5 inches long, and it will be a solid piece with no holes in the "tail" as the 9mm and 5.56mm ejectors have.

 

I have an original HK91 that after only 20,000 rounds did I ever need to replace a part and that was a $4. extractor spring. Nothing else was loose or worn.

Problem prior to extractor change was simular to yours, jamming and failing to eject empty cases. Changed extractor spring and all was fine.

If you can move/wiggle the extractor with your finger then it is not tight enough.

 

Bring an old tread back to life since initiator is looking at a new HK91.
Next step is checking bolt gap on a clean rifle.