I'm a bit of an avid P80 builder. But unless you're a machinist or have access to the right equipment.... I wouldn't even think of trying to mill the slide myself. The milling needs to be very precise, naturally. I'd either send the slide off to a pro or buy a pre-milled slide (which is what I've done).
I have a Trijicon RMR on my home defense pistol (for many years). But I installed Holosuns on two of my P80 builds. I like the Holosuns better than the venerated Trijicon RMR, honestly.
For my PFC9 (serialized P80 frame) EDC pistol, I got the Holosun 507C (green) with the ACSS Vulcan reticle that
@Namekagon mentioned.
View attachment 8233582 The ACSS Vulcan reticle is the bee's knees, IMO. Especially good for learning and training for consistent presentation from a draw and quick acquisition of the "dot."
Holosun's infographic on how it works:
View attachment 8233584 Then I made my own infographic:
(getting the reticle in sharp focus is difficult with a camera, but it's very sharp to the human eye).
View attachment 8233583 Once you've dialed in your presentation, you won't ever see that outer circle.
For defensive shooting, I really REALLY like the chevron. If it's bullseye shooting, then the small dot reticle is better, of course.
Ummm... no. It depends. Bigger dot for faster acquisition / visibility... has advantages for defensive weapons. But if you're a competitive bullseye shooter, a big dot will obscure the bullseye, especially at longer distances. It will be less precise. If you're a bullseye shooter, a smaller dot is preferable.
That's why Trijicon offers their pistol optics in various dot sizes. My home defense pistol (FNH FNP-45T) has the Trijicon RM07 with a 6.5-MOA dot. That's a big dot. But it's for defensive use (big target). For more precise bullseye use, I'd go down to a 2-MOA or smaller dot.
Whether the rear sight is in front or behind, it will block a portion of the window. Some believe that it's "less intrusive" when in front of the optic. I agree it looks funky.
So, it depends on how tall your iron sights are. Personally, I think the whole notion of "co-witness" is really bullshit. The claim is that you'll use them if the battery craps out. The chances of the battery crapping out goes to zero if you simply replace your battery on a scheduled yearly basis.
If you want to have iron "back-up" sights, I'd make them as short as possible.
Finally... realize that it will take some time, training, and practice to become proficient with a pistol optic. But, I can honestly say at this point I am considerably faster with an optic than I am with iron sights. And as a person whose eyes aren't what they used to be (cannot focus on a front sight unless I'm using "cheaters" (glasses).... the optic reticle is always sharp (without glasses).
Another BIG advantage of pistol optics is the ability to stay "threat / target focused." You focus on the target and simply bring the "dot" (or chevron) up to be superimposed on the target. No shifting your focus like is required by iron sights.
