I have had a G20 for 7 or 8 years and I finally decided to get a 29. I got a new 29SF, serial # TRB*** with a test fire date of 8-21-12. I went to the range yesterday and put 100 rounds through it. I had 1 FTF at about the 25 round mark. This is the first malfunction I have ever had with a stock Glock (almost 50% FTF in my 20 with Lone Wolf barrel). I aso noticed that if you ease the slide forward, gun empty-no mag, the slide does not close completely. None of my 3 other glocks do this. I seem to recall that this is a problem related to the trigger bar? but I could not find anything in a quick search of this forum. Ammo used was Freedom Munitions 180gr rated at 1200 fps. I have been running a 22lb ISMI spring in my G20 with no problems. I would like to go to something a bit heavier than the stock 17 lbs in the 29SF. I have done some web searching and it seems that all of the dual spring assemblies use the standard 17lb springs and that if I want gomthing heavier I would have to go to a single spring assembly. Is there a dual spring assembly that offers different spring weights? Thank you for any help!