I bought a new Dan Wesson Guardian in 9mm a couple of months ago.  The gun is the least reliable 1911 I have ever owned or shot.
Day 1- The gun would consistently leave the last round, after being fired, sitting on top of the magazine inside the gun with the slide locked back.  It would extract it from the chamber but wouldn't eject it.  
In the weeks that followed, the slide would lock back after firing a round and would still be holding onto the spent brass.  The only way to clear that failure was to pull the magazine which usually meant a live round was partially in, or trying to load into the chamber adding to the complications of dealing removing the casing.  
The gun has now found it comfortable to fire a round, lock the slide back, and leave the spent casing approx 1/8"-1/4" out of the chamber.  If you tilt the gun backwards the spent case usually just falls out, the gun is clean and there doesn't seem to be any resistance on the case as gravity usually removes it.  You can then slingshot the slide, or use the slide release and fire again.  If you tap and rack you will create a double feed so it's a fairly debilitating problem if you were using the pistol in a CCW or LE role.  
This weekend the gun decided it was bored with previous failures and mixed up the failure to extract from the chamber with some good old fashioned stove pipes.  Not upright stove pipes that you can draw you hand across to clear and keep shooting, horizontal stove pipes when the slides closes that allow another round to lift out of the mag and start to chamber.  
-The problems has occurred since day one.
-I have had numerous shooters, some quite accomplished others were amateurs shoot the pistol.  One of the shooters went to Bob Marvels gun class where you build you own 1911, that doesn't make him an expert but he spent 2 weeks building a 1911 and has at least a basic understanding of how the function.
-I have shot all factory, different brands, 115, 124, 147 grain ammo.  Also 147 grain Federal HST which seemed to be the most accurate load.
-The longest I have gone without a failure occurred saturday, 2 9 rounds DW mags and 1 10 round Wilson combat mag fed and fired.
-The brass is all over the map, some trickles out, other brass goes 3-4 feet out, all in the same magazine.

CZ/Wesson customer service told me the CLP oil I was using was wrong, and that I need to be using FP-10 oil.  I bought FP-10 oil, no change.  
Customer service said that I may be touching the slide while shooting which can induce a malfunction........OK, definitely possible although I've never seen that as the reason a pistol malfunctions.  
I tried tea cupping, one hand shooting, strong two hand with shoulders rolled in and elbows pushed out a little.  I have watched numerous other shooters shoot the pistol with disappointingly similar results.  
I bought wilson combat, and checkmate (they make DW mags) magazines in case it was a mag related issue.  

Has anything else had any issues with their 9MM Dan Wessons?   What was their customer service experience like?  As a full disclaimer, I had a DW Valkyrie in .45 that has over 5300 flawless rounds through it, I like DW but this gun has been nothing but a headache.  Please let me know if anyone has had good or bad DW 9mm experiences.

                                               Thanks,
                                                          Woody

Tagged

I would request a RMA label and return the pistol to DW for service or replacement, those
types of Issues from a brand new DW factory pistol are unacceptable...

Since you likely ruled out a magazine Issue the next area to look at would be the extractor.
It seems like that may be your primary cause of the malfunctions...

Also, check the ejector for looseness or Incorrect fitment, or burrs, there may also a Issue
in that area...

Then I would look at any burrs or sharp edges in the slide, chamber area for any possible
Issues...

Finally, I would look to see what the recoil spring weight is like (In a 9mm 1911 you should
have a spring weight with a minimum 10 lbs. to about 14 lbs. max.).

These type of Issues are not very common on a new factory DW but they can happen, this
particular pistol may have missed the QC live fire testing or was just a lemon that should of
never left the factory...

Good luck.

DR69ER, all of your comments were logical and thoughtful.  I am going to send it back, being brand new I don't want to attempt some cob job repair that is later pointed to as the reason why the gun never worked in the first place.  Also at this price point I would prefer all of the work be completed at the factory.  Finally, if for some reason it is repaired and the fix doesn't actual fix the problem it would be more important than ever that it was factory work done by Wesson/CZ staff.  
                                                 Thanks,
                                                            Woody

Woody, my VBOB gave me fits out of the box. Every failure known to man, and a slide that locked up so tight I liked to never got it back off the frame. I don't think I got through ten mags without a malfunction in the first 500 rounds I fired.

(Gently) stoning the sharp edges off the slide fixed the lock-up, and an occasional failure to return to battery.

The failures ALL turned out to be a badly out-of-tune extractor. Checking the tune and correcting it if necessary is simple. Go back to your buddy that went through the two week course if you're not comfortable doing it. Once you think you've got it right, run the 10-8 function check on it a couple of times.

10-8 Function Check


Good luck, I know it's frustrating as shit.

Osprey,
          What you are saying makes sense but I'm going to send it back.  I don't think at that price it should be my job to fix something that basically came to me broken.  I also don't have a high tolerance for expensive things that come to me in a condition that is less than what is advertised.  If I had bought a RIA (nothing against them, just a simple price comparison) I would be more willing to do some home gunsmithing.
                                          Thanks,
                                                     Woody

My pistol is repaired and on its way back to me according to CZ.  Below is the list of things they did, and Ill be shooting it a lot this weekend so I hope its good to go.

Your repair has been completed and will ship shortly.

Item: 01985 - DW GUARDIAN, 9MM, BLACK AL, BO

Serial Number: ******

Description: FTE

Work Performed: Recoil spring correctly re-installed. Extractor tuned and cleaned. Chamber reamed, throat and feed ramp polished. Test fired, no issues.

Once your firearm has shipped, you will receive an additional email with tracking information from FedEx within 24hrs.

Best Regards,

CZ-USA

I hope it gets worked out for you! I've had my eye on a 9mm Guardian but threads like this always make me wary.

If anyone is following this.  The gun has had 1200 rounds through it without issue since it was returned.  The only two issues are the guns unwillingness to load a round from slidelock.  Every 4th or 5th mag the slide will fail to lock closed.  I am probably getting rid of this gun as I don't trust it.  It does technically run 100% when it is loaded, the problem only occurs when dropping the slide on a loading mag, sling shotting the slide does not fix the problem.  This gun isn't suited for a defensive role.
                                          -Woody

Man you have had some horrible luck of late.  You must have near saint patience. I would be nuclear right now if it was me


That gun isn't 100% if it doesn't load from a mag reliably it's wrong period.  That's virtually a 20% failure rate as you describe it.
I don't know how they actually deal with warranty issues? According to the stated warranty only the original purchaser gets warranty work.

For anyone interested......
I have had my 9mm Guardian back from DW customer service for a little while now.  I have put well over 1,600 rounds through it since getting it back.  Yesterday I put 300 rounds of fiochi 115 grain FMJ through it.  The gun has run 100% and shoots very nicely since it came back from DW.  I specifically ran it for the first 1,000 rounds since getting it back without cleaning or oiling it.  That's obviously not an amazing feat for many other pistols, but this gun basically wouldn't run before so it's a huge deal to me.  

My only complaint, is that the gun may be undersprung.  I dont have ANY experience with 9mm 1911 pistols besides this one.  When I drop the slide on my .45 DW and ed brown pistols they move forward with force and purpose.  This gun feels like it has the exact amount of spring tension needed and not a ounce more.  Has anyone experimented with their spring lbs regarding the recoil spring?  I don't know what a stock 9mm DW is.  Any thoughts/comments/questions would be interesting.

                   Thanks - Woody

I like at least a 10 pound spring in 5" 9mm 1911s and a little more if the gun will run reliably.  Add 1 or 2 pounds for a 4" gun.

19 pound mainsprings seem to work pretty well too.   I don't like to go lighter than 17 pounds because I've found I will eventually start getting light strikes.

The factory recoil spring is 12# I would try a 13 and 14 but would also check to make sure the extractor Isn't to tight also it sounds like your original problem was the extractor was to loose. It may be overly tight now. 9mm are a joy to shoot but can be finicky everything has to be right for them to run 100% 45 will overcome some shortcomings that a 9mm will not.