My 625 will not hit hard enough in DA. I have replaced the mainspring and rebound spring but it is still not functioning correctly. The new mainspring is a "standard" spring and not a reduced power. I am not that interested in a faster or easier trigger pull. I want the gun to shoot whatever is put in it. Does anyone have any suggestions?

Is the ammo factory or reloads?Does the gun have a hammer or frame mounted firing pin?Have you replaced the strain screw?

I fit has a frame mounted firing pin get an extra long firing pin from either Apex or Cylinder & Slide. Also fedral primed ammo will go off easier with a lightened hammer strike.

I have used both factory ammo and reloads. It does have a frame mounted firing pin. I have not replaced the main spring set screw it is the factory original. Where would you get a new one from? I have thought about lengthing the firing pin but this gun worked fine when it was new and now it doesnt. I just figured the springs were fatigued and replaced with a Wolff "standard" mainspring but it still doesnt perform in DA. Are there any "stronger" springs available?

What you probably need is a new Strain Screw. These are available from sources such as Numrich's, Brownell's, or Midway. However, stocking levels on small parts such as this do vary so you may have to check all 3 sources.

There are 2 different strain screws available for your 625, one in blued steel and one in stainless steel. If you are using a grip that covers the front strap of your grip frame I would suggest that you use the blued steel strain screw, word on this site is that the stainless strain screws are softer and prone to peening at the tip. I'll also warn you that you'll need a Round Butt strain screw for a Round Butt grip frame and Square Butt strain screw for a Square Butt grip frame.

Once you have that new strain screw I would suggest that you re-install the mainspring that came with your 625. These springs are NOT worked very hard so they'll take many many years to wear out and I have more faith in Factory parts than aftermarket with items like this. Then make sure that you tighten that new strain screw down completely.

That should result in a DA trigger pull of 12 lbs. or a bit more and should solve your misfire issue. If not, remove your firing pin can use some digital calipers to measure the overall length. If the overall length is under 0.490 inch you can purchase a 0.495 inch firing pin from Apex Tactical or Smith & Wesson. With a 12 lbs. DA trigger a 0.490 inch firing pin should provide perfectly reliable ignition. If not, I would suggest contacting S&W because something more fundemental has gone wrong.

Check the endshake, if it is excessive, then that may be part of your problem.

i had the same problem with my thunder ranch revolver. i put in a longer firing pin and still had the problem. it only happened with reloads, factory fired fine, but i mostly shoot reloads.
i decided the spring needed more tention so i put the strain screw in my lathe and removed a few thousands from underneath the screw head so it would go in more, after this the gun works with all loads factory and reloads.

Using Federal Large Pistol primers cured this on my 625 JM and my 325 NG

First try Federal primers they have the softest cup and are easiest to ignite..
If that does not cure the problem get the extra long firing pin from either Apex or Cylinder & Slide.

Thank you to everyone who has responded. I really cannot thank you all enough. I am going to invest in a strain screw and do a little measuring. Thanks again for all of your help.

you can try putting a spent primer cup over the strain screw between the screw & mainspring for diag purposes. hth.