I seem to shoot a little low and right with the stock 40 s&w and also, the KKM 40-9mm conversion barrel I'm using right now. When looking at the rear sight in it's windage slot it is for sure, closer to the right side of the notch. My question is should the rear sight base be perfectly centered in it's Dove-tail notch? or how does one go about lining it up to be correct with the front sight? The front sight seems to have an even margin on both sides of the adjustment slot. The rear sight base is almost flush with the right side of it's dove-tail slot. Any ideas on how to check, or measure and make sure the rear sight is correctly lined up with the front are all welcome. Thanks!

have you shot this pistol from a stable bench rest? That may tell you if it is on sight or not, also you can check if the low right is because of your trigger squeeze, while you are rested on a bench. If its still not shooting center then take notes as to where it shoots and having the rear sight centered may be needed.

I'm having this issue with a .40 full size I just bought. I'm a right handed shooter, so any errors in trigger press will manifest themselves in a low left group. However, this gun shoots high and right (off sandbags, at 15 yards). Like 4+ inches right. Looking at the rear sight, it appears centered in its dovetail. The front sight also appears centered. I will try drifting the rear sight to the left to see if I can correct the windage error, but it doesn't look like there's much room in the dovetail to work with, unless the sight is going to hang out the side of the slide.

I'm almost wondering if this is a barrel to slide fit issue.

The groups, however, were very good. Factory ammo was grouping 1.5" at this distance, and a handload of mine using a 155 gr. lead round nose bullet over 5.0 grains of HP38 put 4 out of 5 shots into a ragged hole, with the 5th being 1" away (probably me).

You don't have to move the sight far to make up 4" at 45 feet. Look at your target through your sights and move the point of impact 4", the sights barely move a few thousands of an inch.