My SDM fiber optic front sight was in my mail box when I got home this evening.  Bad news=  It's just a bit too long in the base to be a "snap in" interchange as the 625 JM is designed.  What I had to do was to drive out the roll pin that serves as the forward pivot for the sight, insert the sight, push it back against spring tension, and drive the forward pivot roll pin back in to hold it all in place.  I think I'll have to drive that pin out again to remove the sight, too.

 Good news=  The .250 height hits to the same point of impact as the factory front sight.  I didn't need to change elevation/windage at all.  I'm going to shoot a USPSA match with it tomorrow and daylight was almost gone when I finally got the sight installed so I sighted in with a flashlight propped up to shine on the target and another flashlight over the fiber optic sight to make it glow.  I'll know better if I like the sight or not after shooting it under better lighting conditions tomorrow.

Scott