My son and I went shooting today with the 5904 and a S&W MP Shield 9mm. The 5904 shot great and had no issues. Tonight we got home and he disassembled both guns and cleaned them. When he reassembled the 5904 the trigger is completely slack in all positions. Safety on, slack. Safety off hammer forward, slack. Safety off, hammer cocked, slack. When you disassemble the slide from the body the trigger works again in both single and double action.

I remember this happened 15 years ago when I first bought the gun and cleaned it. I do not remember how I fixed it or what the cause / solution is.

Any ideas before I go to a gunsmith?

Did you check trigger function with no mag in the gun? Trigger will not work without a mag in the gun. 5904 has a magazine disconnect.
Jim

Duh.... wow

I just taught my son this week how to do a functions test and I taught it with mag in for this exact reason... I don't know why I brain farted tonight. Thank you.

You are welcome. Im glad that was all it was.
Jim

glad to see a happy ending

I think the mag disconnect / safety is one of the greatest designs in firearm history. If a LEO were fighting to retain their gun he / she need only hit the mag release, it probably saved more than a few lives. I wonder if there are statistics kept on officer shootings since S&W's went off LEO service belts and tactical tupperware took its place?

I agree. However, since the late 80's holster design and retention training has advanced. Today I would say most departments issue retention holsters.

I AGREE. I SAW (YES, SAW. NOT HEARD ABOUT. I WAS IN MINE OWN BATTLE AT THE TIME) A FRIEND OF MINE FIGHTING OVER HIS 459 WITH A MENTAL. PATRICK WAS 6'4" AND 275 AND WAS LOSING. HE DROPPED THE MAG AND WAS THAN ABLE TO FIGHT WITH 2 HANDS TO WIN. THE MENTAL ACCORDING TO HIS MOTHER WAS A GOOD BOY, " WHEN HE TOOK HIS MEDICINE". THIS WAS ABOUT AUG 1984. THE MENTAL WAS SHOT AND KILLED DOING THE SAME THING TO SOMEONE ELSE ABOUT 2 YEARS LATER. I HAVE NOTHING BUT GOOD THING TO SAY ABOUT THE SAFETY. JIM P

It's not always about holster grabs, though every level can be defeated, they learn how in Crime School (Jail) but also after a LEO has pulled the gun, once it's out he LEO is open to attack and being disarmed.