If you make that choice make sure to take note abot having to shorten the rear screw on the sight mount. If you don't do that it will leave a VERY nasty mark on the cylinder. BTW, when you first fit the mount to the gun, do it with the cylinder OPEN, that will show you how much you have to grind off the end of the screw. BTW, a Dremel with a sanding drum makes quick work of this but be careful to NOT launch that screw into recesses of another dimension.
They also ship the sight with a 1 degree angle shim and that's a good thing. Unfortunately, you'll have to take a try and see what happens approach to determine if you need to use that shim. On my 610, no shim was needed. On my 617 the groupings were low at the maximum elevation setting so I had to install the shim. On the 620 with no shim, I can just get it zeroed with a 125 grain 38 spl. so I've left it without the shim. That way with a heavier bullet, +P, or 357 Magnum, I can adjust the windage to drop the POI. BTW, there is NOT a distinct "stop" to the windage and elevation adjustement, all you will feel is the screw starting to bind. At that point, STOP, trying to force the screw just a bit further will just damage the sight and J Point warns they specifically that WON'T cover damage to the elevation and windage screws caused by forcing them. Note, I've sighted all 3 of my guns in at 35 yards and it's worked out very well, the group will center on the 10 ring at about any distance where I can actually see the 10 ring, be it 15 feet or 40 yards. BTW, at an indoor range I can't actually see the 10 ring, I just center the dot on that tiny target way down range.
I first got into using optics because I can no longer focus on a handgun sight from a supported grip. Because of this my 5 inch limit of accuracy with a post and notch sight is now limited to about 50 feet. With a reflex sight I can cut that grouping by 2/3. It's also made it possible to start shooting handguns at longer ranges again, so I spend a bit of time some range sessions doing a bit of bench rest shooting at 25 to 40 yards.
