I recently acquired a Sig Sauer P229 CO2 Pistol. Although it's a nice comfortable pistol to shoot, the open sights aren't adjustable and (as reviewers have found) are off. One of the key selling points of the P229, though, is that it's optics-ready: the slide is designed to be able to take Sig's reflex sights. This is both good and mildly frustrating: rather than something semi-standard (like a dovetail, an RMR, or a Docter mount), the P229 uses Sig Sauer's proprietary mounts. What this means, in practice, is that it's only really possible to fit Sig's sights. That frustration is made worse by the sights not being widely available in the UK (I had to get mine shipped from Lithuania). However, once you've got the sight, it really is pretty easy to fit and comes with almost everything that you'll need. The only thing that doesn't come with the sight is the optics plate anchor (which comes with the gun itself). This document describes the process of installing the sight. Tools You will need A 2.5mm pin punch A small hammer A small phillips screw driver Allen key (supplied with the sight) A gun bench block (optional, but reduces damage when driving pins through) Process Remove the magazine and ensure that there's no CO2 cartridge in the gun. Unscrew the barrel thread protector (or any attachment): The slide stop lever on these guns is fake and the slide's actually held in place by the forward roll pin: Use a 2.5mm pin punch to carefully knock the pin through: Remove the pin punch and then carefully pull the slide backwards, tilt the back-end up so that it comes clear of the guides and then move forwards again until it slides off the barrel: Set the rest of the gun aside and turn the slide upside down, you should see the two sight anchoring screws at the back: Use a Phillips screwdriver to undo and remove these. The open sight plate will now be loose and can be removed: The reflex sight comes with a pair of mounting plates: one for airsoft and one for airguns. You need the latter: If you remove the protective cover from the sight, there are two fixing holes in the middle. On the underside are four holes which line up with the posts in the corners of the mounting plate. Sit the sight on the plate with the screen furthest away from the two big holes. Then insert two screws and tighten them down using the supplied Allen key: The gun itself came with an optics plate anchor: Position the sight and mounting plate on top of the slide and then push the anchor into the two holes (with the little notches pointing backwards): Holding the sight and plate in place, invert the slide so that you can reinstall the two retaining screws: Check that the screws are tight (the manual suggests a drop of Loctite, but it will make future disassembly much harder). Ensuring that the spring is still over the barrel, tilt the slide and pull it back over the barrel. Click the hammer back to move it out of the way, then pull the slide all the way back before lowering it and carefully sliding forwards over the guides. You should see the slide stop sticking down inside the trigger guard: Push it up into place. Push the rollpin back into its hole: Use the pin punch and hammer to tap the pin back into place. Turn the safety off and operate the slide and the action to ensure that everything feels OK. Screw your muzzle attachment back onto the gun: You're done! Zeroing Zeroing is performed using two adjuster screws: Windage on the side Elevation on the top Both are secured by two locking screws on the back of the sight (visible in the photo above). Using The sight projects a red dot onto the convex lens which gives very slight magnification: Pressing the power button multiple times changes the brightness of the dot, holding it in powers off. Because the sight is attached to the slide, it moves backwards and forwards as you fire: This means that it takes a bit of a knocking, however the two screws on the back of the sight are use to lock the adjusters so that it doesn't drift out of zero. Just to close with a bit of nerdery, let's calculate the speed that the slide travels at: The video was shot at 30 FPS and the slide cycles within the space of a single frame, so Slide_travel = 34mm # Distance per second 34mm * 30 = 1020mm # Convert to hours 1020mm * 3600s = 3,672,000mm # Convert to miles 3,672,000mm / 1,609,344 = 2.28mph So, as fast as it seems when shooting it's actually travelling at about walking pace.