Sunnenman,
1. Check the strain screw. If you don't know, it's at the bootom of the grip on the front. It tensions the mainspring, and has a tendancy to backout under recoil. I've also found that S&W doesn't always get all their screws tight. Some people loosen the strain screw to reduce trigger pull -- not a good idea for reliable ignition.
2. I'm on my third 329 PD. The first one self destructed (not an ammunition problem), and it was replaced by S&W under warranty.
After 25 magnum rounds or so, the lock malfunctioned on the replacement (329 #2), and tied the gun up. Worked it loose, and tried again -- totally tied up. Took it home and removed the lock.
Next, it (#2) started giving me ignition problems after several hundred or so rounds of magnum level loads. It would work for several rounds, then I would get "pin prick" like firing pin hits and no ignition (checked strain screw and it was tight). Some would fire when struck again and some wouldn't (this went on for a couple of days). The misfires would all fire in a 629. Rather than send it back to S&W, it took it to my smith. He cleaned everything up, and added a shim to correct some end shake (headspace). Took it to the range, and it worked for 46 rounds before first stoppage due to "pin prick" (very weak, almost non existant fireing pin hits). Took it back to my smith. Looked it over, did something else to it. Took it back to the range, and after about 12 rounds, same symptoms/results. Put it down and shot a differnt gun for a while. Just before quitting for the day, I tried it again -- it worked for 3 rounds and quit.
My next move was to order a Cylinder & Slide Shop "Long" firing pin and had my Smith install it. First 4 rounds, great firing pin hits -- on the fifth round, the firing pin jammed forward and locked up the gun. Managed to work it loose, and "Dumb Me" tried it again -- locked up tighter than a drum. Took it back to my Smith -- stuck a brass rod down barrel thru empty case and tapped the fireing pin back into the frame
(WARNING!!! MAKE SURE THE ROUND HAS FIRED -- CHECK LENGTH OF ROD ON OUTSIDE OF REVOLVER FROM END OF BARREL TO BACK OF CYLINDER (NEAR HAMMER) AND MAKE SURE ROD GOES IN PAST BBL/CYL INTERFACE AND INTO CYL AN INCH OR MORE). He took the pin out, and lightly polished it and the hole in the frame. Back to the range, this time with brass rod. Locked up after second round -- tapped pin back, and tried again -- same result. Back to the Smith/range with same results. I finally replaced the factory firing pin and sent it back to S&W day before yesterday.
3. Bought my third 329 the middle of last week. Have 210 rounds of mag level rounds thru it to date with absolutely no problems. Now that I have (or will have when I get the one back from S&W -- fixed I hope) two 329s, I will probably have no futher problems, but if I do, I will recycle thru S&W warranty shop.
I'm not bad mouthing the 329 because I really love this gun and carry it's pretty much my every day here in Montana. Don't know whether I've just been unlucky, or if "Murphy" is stalking me.
As mentioned above the S&W 500 Hoques make the 329 shootable. I shoot a a dozen or so rounds about 6 days a week -- it's the one gun I shoot every time I go shooting.
One thing to remember is that these light weight guns are hard to shoot -- the lack of weight makes them real hard to keep steady while working the trigger.
Here's a picture of #2 (before it started malfunctioning) with the Hogue grips installed and in a Simply Rugged Sourdough Pancake holster:


Paul