My wife bought a 617 to compliment her 625. The first time I shot it to sight it in for her the trigger stuck back on the second round. I pushed it forward and continued. When I got home I pulled the gun apart and was kind of surprised at the differences from the older models. The main thing is that it looks like the interior of the frame is cut out using EDM. it has a relatively smooth but porous looking surface that has considerable drag when you run your finger across it. I put some polishing compound on the frame and rebound slide and worked them a bit and it really improved things. A few weeks later I gave it to a gunsmith that belongs to our club and he made that new gun just as smooth and light as an old model 27. My wife is a happy camper now.