I'm sorry for your bad experience, and have no easy answer except contact S&W and ask what they plan to do for you. Remote possibility - Did you check the serial number - are you positive it's the same gun you sent them and not a mixup?

I had a similar experience with Smith and my 25-5, which I bought new and had been an unfired safe queen until a few years ago. Mine had .456-.458 cylinder throats and patterned like a shotgun , also ~6" high at 25 yds.

I contacted S&W, and Smith told me that since it was made by "old" S&W, there was no warranty or new cylinders available. A couple years later, cylinders became available, so I sent it back, requested cylinder replacement and a master action job on my dime. When I sent it off, it had less than 50 rounds through it, was immaculately clean, and had a nice crisp trigger.

About three weeks later, I got it back with new style bluing on the cylinder which was more black than blue and did not match the old bluing, the sharp edge of the side plate was bent back in two places where it met the frame, one side plate screw was bubba'ed with a gouge from the slipped screwdriver in the side plate, there is a mark similar to yours where the yoke bypasses the frame when closing, there were fine sandpaper-like scratches all over the frame face opposite the side plate, and the trigger was no longer crisp, but had substantial creep, and the gun was filthy with finger prints and powder residue all over it.

I cleaned the gun and removed the sideplate to see what they did, and was shocked to see that all the case color was buffed off both sides of the hammer. Apparently their slicking of the action consisted of jamming the hammer into a buffing wheel, which no doubt altered the sear notch and induced the trigger creep. There was no indication of the usual careful stoning of the rebound slide or certain small contact surfaces on the hammer and trigger.
I'll never send Smith another gun of mine.