Gents I need some assistance. I have an Olympic Arms preban lower and a Bushmaster M4 preban upper. I just got back from the range and my rifle fires fine, but the spent casing does not get ejected all the way.

It has a telescopic 3 position stock(came with the oly) and the fit between the upper and lower is nice and tight no play what so ever.

I purchased the bolt from J&T Distributing.

What is causing this to happen? Is it the buffer spring? Is it the extractor on the bolt?

I have fired single rounds and occasionally it will fire and extract correctly, but once there are 2 or more rounds the spent casing and the new round get jammed in the upper.

When I fire a single round it sends the bolt to the rear but sometimes the round is just sitting on top of the magazine.

I used Winchester and South African rounds and I used 10 GI mags.

Thanks

Check your bolt carrier, more specifically the carrier key.  Check to see that it is not loose or cracked.

Have you taken the rifle apart to give it a deep cleaning. There could be some crud behind the ejector.

Ejector spring missing?

Could be a defective/weak spring spring underneath the extractor, or a bad extractor.

Quoted: Have you taken the rifle apart to give it a deep cleaning. There could be some crud behind the ejector.

That's what I was thinking.

Might not have a spring behind it either.

Quoted: Could be a defective/weak spring spring underneath the extractor, or a bad extractor.

He said the casing is getting jammed in the upper with the fresh round so the extractor is working just fine.

Could the bolt be in the wrong way, having the extractor facing the wrong way?

Quoted: Could the bolt be in the wrong way, having the extractor facing the wrong way?

I never thought of that.

Maxell:  Make sure when you reassemble the bolt that the extractor is on the side of the receiver that the ejection port is.

Thanks for the input guys

I have given the rifle a good cleaning before I shot it.(Marine Corps clean)

The extractor is in the proper position.

There is a spring underneath the extractor complete with the silicone insert.

I am thinking of trying another extractor and spring.  I tried to file a burr on the lip of the extractor that I noticed maybe that will help.

Thanks

max

Couple of things you can try next time you are at the range.

Chamber a live round but don't fire it. Pull back on the charging handle and see if your rifle ejects a live round OK. Live rounds weigh more than fired ones because of the bullet and therefore put more load on the ejector spring. If you have a weak spring it may show doing this.

Something else you can try is to put only 1 round in  your mag and chamber it. Then fire the round. The casing should eject and your bolt should lock back.

Inspect the carrier key to top of the carrier. That surface should be FLAT AND CLEAN upon re-assembly. TORQUE the 2 bolts to 35-40 in-pounds, then stake the screws in 3 places.
As to the extractor spring-insert, advise the black insert, though the blue will suffice, but a shorter length of time. The last place to look is the gas port under the sight base. You will probably find that you may need to open slightly, usually around .083 does the trick.

Really sounds like an extractor problem to me.

Just a thought:  remove the bolt from the rifle, take an EMPTY and snap it on the bolt face (you’ll have to pivot the rim of the empty under the extractor – you’ll also have to fight the pressure from the ejector), then see if you can pull the empty straight away from the bolt.  This should be just about impossible to do; the extractor should refuse to let go.

While you’re doing this, you might also make sure the ejector is pushing back nice and strong (you are lubricating it, aren’t you?).  However, this doesn’t sound like an ejector problem (if it was, the empty would remain held to the bolt by the extractor).

Also, do the empties look ok?  

 Had the same problem, due to a weak extractor spring.  Brownells' lists a Wolff extra duty extractor spring, and it is highly recommended.  Try a chrome extractor, they are harder and wear better. If you found  a burr on the extractor, trash the extractor and spring. and replace them with new ones.  This is the weakest part in the design, so don't F with it.

Gents,

 I replaced the extractor, insert and spring today and tried it.  It fired very well however it did have a few more failure to extract.  I checked the bolt face and noticed brass particles there.  I cleaned it off with a nylon brush loaded a 28 round mag and fired them all off without a hitch.  I guess it was the South African Surplus ammo.  

 All in all I am pleased.  Thanks for your input.

MAx