Being from Massachusetts, and our very restrictive gun laws, it took me a couple months to source and purchase my M9 A1, and I quite like the trap sights. But I was curious about adapting the slide for a red dot. Though having the slide milled is arguably the best way to go, there are other options available. I kind of hate altering the slide considering how long it took me to find the pistol. So, after a few weeks of research, here's what I found.
Available Adapter Plates. Subtle Differences:
The most well-known plate for the M9 is the Outer Impact MRA. The price is good at $55, and the wide variety of red dots that can use this plate is pretty impressive. The plate is a 7075 aircraft build, and looks like a rugged slab, ready to go. The company is in the US, which is a plus. The web site is very helpful in showing how the plate is installed.
The M9 is a nice-looking gun. Adapter plates are not especially aesthetically pleasing. They tend to hang out over the edges of thin-topped slides with angles. Think Walther, and in my case, the Steyr. However, I found another manufacturer with a really small design detail that makes a big difference to me. It's just a little side skirt that drops below the top of the slide.
This plate was hard to find, and I first discovered it on Amazon. It's manufactured by Oceania Defence (yeah, that's spelled right.) This company is based in the UK. Oceania's plates are custom-shaped for a variety of individual pistols (20 or so.) Each plate has a slightly different profile, according to the make and model. And I like the fit on the M9 better. It's more expensive, and cost $71.
Yeah, ok, I'm too picky. However, the ODefence model nicely covers over the dovetail so you can't see it from the side of the pistol.
You can see the obscenely minor difference when looking at the slide from the rear. It does appear, though, that the Outer Impact plate is thicker, and, perhaps, stronger. I haven't the slightest idea.
Oceania will also sell you a suppressor-height iron sight that screws into the plate behind the optic. Outer Impact may offer this too, but I'm not sure.
The installation of the plate is pretty straightforward. Remove your iron sight. Install the dovetail adapter, screw on the plate, Place a pair of the retention pins where appropriate, and then screw on the optic. I think my Vortex Venom is a little tall, but that's the optic I have on hand, and it also fits nicely the width of the plate.
So far, with 400 rounds, my Oceania Defence plate is holding up well.