Got one of these to put on a Ruger 10/22 Tactical (16" heavy barrel) and had it out to the range first time yesterday.
Overall I really like this. They've fixed all of the shortcomings of the II model - battery can be replaced without removing the sight, click adjustments and adjustable brightness.
I'm 63 with OEM eyeballs. My far vision is good but front sights on rifles are pretty blurry these days. With this Fastfire I can use the unaided eye (behind generic shooting glasses) to get a sharp view of the dot while still seeing the targets out yonder clearly. That's pretty much why I got the sight, I wanted something smaller than a scope that still lets me use my unaided eye. This Fastfire fills that role perfectly.
I got the model with the Weaver/Picatinny mount and the cross bar did not fit into the cross slot on the Ruger supplied "Weaver style" scope base, it was too big and wouldn't fully seat. I had to enlarge and deepen the slot with a small file to get the mount cross piece to fully seat but once I did everything snugged up properly. It may or may not fit in an actual Weaver or other brand scope base but it's something to check on. I plan to switch this sight to another rifle in the future and will take it into the store with me to verify the fit on whatever base I buy.
On mine the windage adjustment clicks were positive, the elevation clicks were barely perceptible. They were there but you need a safecracker's sensitivity to feel them. Despite the elevation clicks being very soft, the movement is spot on. I sighted in at 25 yards and then moved out to 100 using a 25 yard slow fire pistol target with a 6" bullseye. With a center hold the first three shots were 3" low, right at the bottom edge of the black. Each click = 1 MOA so I put in three clicks up elevation and the next three shots were centered in the 10 ring. Easy peasy.
I have read where some people had to max out the elevation adjustment to get on target but I had no problems with this one. The 100 yard sight in is with the elevation and windage adjustments pretty well centered with lots of adjustment left.
The adjustable brightness is a great help. It has five settings - auto, bright, medium, barely there and then off. You have to cycle through each setting in that order. The little button is kind of hard to push, I had to use the very tip of my finger and it would be difficult with gloves. A minor shortcoming but if they made it bigger I can see how it might get bumped.
On auto adjust the dot was too bright even in full daylight, it was the same as the full bright manual setting. It is a 3 MOA dot but the brightness washed out even the 6" bull at 100 yards. The medium setting was perfect, it was easily seen in daylight but let me center it with a nice ring of black around it. I was just resting my front hand across sandbags but the sight picture was precise enough to let me shoot a 5/8" three shot group. That's spectacular performance in my book, I couldn't have done any better with a scope.
After sighting in I moved to a 4" ringer at 100 yards and had no problems keeping it swinging from the kneeling position. The medium brightness setting let me put that dot right in the center of the target whereas the brighter setting covered the whole thing and made fine aiming difficult.
The back of the sight has a big white vertical stripe pointing to where the dot will appear so it helps with sight acquisition. I had to re-learn how to mount my Mk III pistol to acquire the dot when I had a Fastfire II on it but with this Ruger 10/22 the bead appears right where your eye is looking when you mount the rifle.
For quick acquisition and larger targets I'd use the full bright or auto bright mode, but that dimmer and smaller to the eye medium setting is great to have for more precise work. That lack of really precise sighting ability was what eventually led me to sell my II models.
The sight is supposed to be waterproof at least from light rain and it comes with a removable cover that lets you still use the sight with the cover on. It's a big mailbox looking thing with glass at front and back. Kind of fugly but it really covers the whole sight while still exposing the settings switch. I can see how it protects the sight much better than the form fitting one of the II model.
Got mine on Amazon for a bit over 200 bucks with free 2 days shipping, that's with Amazon Prime. It comes with the sight, cover, the mount, three screws to attach mount to base (it only needs two so they give you a spare), a screwdriver for adjustments and a torx wrench for the mount screws.
I'd love to get an Aimpoint but they're three times the cost and bigger to boot. If you just want a nice, small but rugged sight for a pistol or rifle for plinking, informal target work or hunting I can certainly recommend the Fastfire III.
Covers the sight and you can get mail delivered right to your rifle!
Side pic showing the size. I like how you can adjust the position to your liking and use any of the four cross slots available.
View showing the vertical stripe and greatly improved adjustments. No more locking screws and ambivalent adjustment settings. Plus an easily accessed battery.