Which gunsmiths do trench sights and for how much?

Don't know of anyone specifically offering the option. Anyone with a good mill, a mill vise, a ball endmill (~.250"), and reasonable skill should be able to fix you up. Endmill could be larger diameter for a wider trench. You could even use a square/flat end mill for a flat bottom cut. The main concern is controlling the depth of cut forward of the ejection port to avoid getting into the locking lugs too deep thereby risking a crack/slide failure. Have you measured one with this feature to get an idea? I haven't handled/examined a New Agent to see for myself.

Someone can correct me if I'm wrong, but cutting a groove across/through the existing sight dovetail(s) or hole(s) does not seem like a good idea.

I hate it when someone harangues me. It would be fugly to leave the dovetails empty/open, but it would work OK given the sight picture. Probably pick up a lot of link if not cause a snag issue. I would insist upon something in the dovetail as a filler. Easy enough to do. Up to you how well it is blended/finished.

Options ...

You might consider something like this .....







That is a custom made sight. There are many possible ways to do one, including something that would fit the stock dovetail. Just depends on your exact needs. Better option might be to get a holster to fit the gun. They might be hard to find, but do exist.

Be sure to tell Chuck that I sent ya.

Not sure where you're located or whether you're willing to ship your slide, but there's got to be more than one smith capable of making a sight.

I like the custom sight! I would see if I could get one made. If not, I would just remove the rear sight and shoot the front post only. Trenches suck!

HB