I have a "pre-ban" (funny to say now) PWA lower/CAR-15 upper that I bought years ago and have mil-spec-ed all the internals.  I am running across a consistent failure to eject problem.  I have replaced the buffer and buffer spring and even changed bolts from another AR.  A round is not ejecting completely  before another round attempts to load underneath the spent case and creates a stovepiped case in the ejection port.  Because another round attempted to feed, the stovepipe is weged and a tuff jam to clear.

The only remaining original part is a collapsable stock that was on it when I bought it.  I don't know the stock manufacturer.

I have cleaned everything and fear a cracked gas tube.  I have read about replacing a collapsable stock with an A-1/A-2 and similar problems going away (SWAT magazine Oct/Nov 2004).

Extractor and springs seem fine.

Dos it lock back on the last round in a mag?  If so, then it aint short stroking.  If not, then it is.

Weird... since you swapped bolts.  That would be the first thing to check, but since you did that....  Did you swap carriers at the same time?  Are you sure it is not binding anywhere?

If you didnt swap carriers, check the gas key for leaks.

I did swap bolt carriers when I swapped bolts.  On both of the bolt carriers, I initially found that the carrier keys were even loose after shooting (not when initially installed), but after tightening, they held strong.

It is locking back after the last round.

It does not seem to eject toward the same area when it does eject.

Same problem with 2 bolt/bolt carriers just has me puzzled.

Everything appears to be in working order, no binding and the loading of the initial round runs fine.

It has done this with several different types of ammo also.

I have even refurbed. all my magazines with mil-spec followers, spings and plates prior to this problem.

Tweak?  This one is beyond my feeble skillz.

when you fired your last shot, does the empty case eject normally or stays in the gun?hinking.gif

<Listening intently I'm having the same problems>

got the same problem  more with wolf ammo than without ???

Hey you two - you say you have the same problem.... but have you also swapped bolt carriers with a known good?  You cant assume you have the same problem.... as we diagnose... because you may not have tried what they have tried.

As to Wolf ammo - it is underpowered and I have seen several rifles (even bushmasters) that would not run it very reliably.  Others run it just fine.

First thing to check on your rifle if you suspect short stroking is the bolt carrier gas key screws... that they are tight.

If you are having this trouble, you should post your own thread in the troubleshooting forum of this site, with your rifle, problem, in great detail, and the scenario in which it fails/does not fail to get help.

The thing about the A2 stock got me thinking... Also about not ejecting at the same spot... he
I have noticed this in older CAR stocks (PWA era).  This may or may not be your problem, but logic would suggest this produces shorter cycle length.

Does anyone know the A1 CAR buffer length compared to the current mil-spec one

Sounds to me like a weak extractor spring.  Where the extractor is letting go of the brass too soon because its being over powered by the ejector.  Try a Wolff XP M4 extractor spring.  If that doesn't work you may need a new extractor.  How often are you cleaning under the extractor.  You should be cleaning it EVERY time you clean the rifle after every outing.  If your gas keys on your carriers are getting loose you need to torque them to spec and stake them.  Also try some mil spec ammo like Win Q3131a, Federal XM193 or LC M855.

I had this problem... here is what happened:

Symptoms same as yours, and excessive recoil.  Now, I am a big guy, but this thing would bruise my shoulder after a day at the range.

What was happening, the b/c was coming back too fast, not giving time for the extracted brass to eject.

Cause was probably that a batch of 16" barrels that hit the market about that time (late 80's) had oversized gas ports.

Cure, the easy low cost one, replace the buffer spring with a Wolff Extra Power Action Spring.  

www.gunsprings.com

www.gunsprings.com/RifleShotgun/Colt_RsNF.html#AR

Stock No. 16501 - CAR 15 and M4....................$ 14.99 ea

Years ago, some guys had this problem, and thinking it was not getting enough gas, drilled the gas ports larger.  This just made the problem worse.

Wolff has a standard power, reduced power, and extra power springs for the CAR-15/M4 rifles.  You want the extra power spring.

Also, make sure you have a metal buffer, not one of those crappy black plastic shot filled buffer.

Buffer spring is a possibility.  But in my experience, especially on the carbines, if you go to a better/stiffer extractor spring, you will usually clear up any problems.  Also a dirty chamber will do the same thing by making the spent case "stick" to the chamber walls.  Every time I have had an empty case and a live round stuck together at the barrel extension, polishing the chamber and changing to a "black" extractor spring has fixed it.

Quoted: I had this problem... here is what happened: Symptoms same as yours, and excessive recoil.  Now, I am a big guy, but this thing would bruise my shoulder after a day at the range. What was happening, the b/c was coming back too fast, not giving time for the extracted brass to eject. Cause was probably that a batch of 16" barrels that hit the market about that time (late 80's) had oversized gas ports. Cure, the easy low cost one, replace the buffer spring with a Wolff Extra Power Action Spring.   www.gunsprings.com www.gunsprings.com/RifleShotgun/Colt_RsNF.html#AR Stock No. 16501 - CAR 15 and M4....................$ 14.99 ea Years ago, some guys had this problem, and thinking it was not getting enough gas, drilled the gas ports larger.  This just made the problem worse. Wolff has a standard power, reduced power, and extra power springs for the CAR-15/M4 rifles.  You want the extra power spring. Also, make sure you have a metal buffer, not one of those crappy black plastic shot filled buffer.

The problem with carbine gas systems is that they have too much gas.  Since the gas system is shorter this causes higher pressure within the bolt carrier and gas tube which caused the carbine to operate at higher velocities which shortens bolt and extractor life and makes for harder extraction.  Slowing the system down using a Wolff +10% action spring or H, H2 or 9mm buffer and a Wolff XP extractor spring will help with extraction problems.  Carbines have the bolt opening when the pressure is still high unlike that of a rifle length gas system.

One thing that I keep seeing is people who find a loose carrier key and just retighten and restake. Often, they will work loose again, primarily because powder residue and ash is now on the interface and threads.

A more solid repair is to remove the bolts and key, thoroughly clean and degrease these parts, make sure that no burrs interfere with the key and carrier fitting together cleanly, then reassemble, tighten normally and stake. A drop of locktite on the face and another on each screw doesn't hurt either, but some folks are uncomfortable with it - use it or not as you prefer. Wipe a film of oil onto these parts, check gas tube fit, and go back to work.

The notes on cleaning the extractor, and possibly replacing the extractor and spring are right on point. (the classic "Somebody else thinks so too" comment). Extractors are sometimes the problem, as are the extractor springs.

Billski

Tweak - this is a metal buffer - Fulton Armory and spring from them also.

Thanks for the tips - when I get a chance, I'm going to really scrub the chamber.  I was thinking of trying a D-fender extractor set-up.  I will look at the Wolff srings for the extractor and the buffer.  One of my first thoughts had been a buffer spring, but when I replaced the buffer/spring combo I thought it might be good.

As to the changing of the stock - from SWAT mag - the longer buffer tube/buffer/and spring would probably change things quite a bit.

I have not had a chance to try the stock swap, but hope to Saturday.

I appreciate all the input and any more that may come.

We have had the same problem with CAR and M4 style carbines.  A stiffer buffer with help, as will an H or H2 buffer.  REALLY slows things down, and now both carbines drop the ejected cases in a neat little pile instead of scattering them all over.  The extractors last longer too.  Ops

Exactly.  Rereading the first post in this tread, the brass WAS extracted, it is not stuck in the chamber.

I still believe it is a timing problem (bolt carrier moving back too fast), not an extraction problem.

This failure can be easily duplicated by starting with a stock spring, and clipping off one coil from the buffer spring, then test fire.  Continue clipping a coil and test firing.  By the time you get to 2 or 3 coils clipped, you and have the rifle failing to eject pretty regularly.  

This also shows that it is not short stroking, in fact, it will have excessive recoil, really start to beat up your shoulder.

So, if weakening the buffer spring makes the problem worse... then making the spring strong just might be the way to go.