try emailing john at firstname.lastname@example.org - he has plenty of experience modifying ct laser grips for S&W gen 3 autos.
Sure hate for my first post be be a "need help" but it is what it is. I recently purchased a Crimson Trace LG-359 lasergrip for my SW910. The web site shows that it fits, and it does... sorta. The grip is held in by slots. The front slots on each grip panel locks towards the front strap. The rear groove contact the frame where the drawbar rides. From what I can see, most 9mms (like the 5900 series), the drawbar is relieved at the back corners. The rear slots would have the clearance to attach to the frame. On my 910, the rear of the dragbar is squared. Once the grip is installed, it interferes with the dragbar, not allowing it to go all the way back. Essentially turning my 910 into a single action only because the trigger can't go far enough back to reset itself. Maybe this is the wrong mechanical reference, but that's the best I can come up with.
In any case, my first thought was to remove the drawbar and relieve the corners. There seems to be plenty of metal but am concerned with safety. The other option would be to replace it with another drawbar from another model, if it was compatible.
I've attached some pics, plus one I found on this site.
Any thoughts or directions I should be heading?