XS sights makes them for the earlier, pencil barrel Mini's. A new-in-package set was included when I bought my 186 series from a friend. They use Trijicon lamps.
Some notes on installation, which may or may not apply to all mini's!
1) An arbor press, and every pound of its 1-ton capacity, was required to remove to stock sight (even after soaking overnight in Kroil.)
2) The barrel was not blued under the stock sight sleeve. It appears that Ruger blued the whole barreled action after assembly... Makes sense, from a production point of view. Don't know if this applies to series Mini's.
3) The sight base sleeve of the XS front site is shorter in length than the stock sleeve. This left exposed the in-the-white portion of the barrel. I had a devil of a time getting the cold blue blended to match nicely.
4) The bore of the XS Sight sleeve is waaayyy undersize to fit the barrel. Not being a machinist, it took a long time to do a nice, even job of getting a good, slight, interference fit. (And then cold-bluing the inside of the sleeve...)
4a) The diameter is also way beyond doing a heat-shrink interference fit, and the heat destroys the Loctite (yes, Loctite) that holds the sight blade in place in the base's dovetail. Also, this dovetail is a rattley-loose fit. That said, the package includes a fresh tube of Loctite, and a phone call to them confirmed all of this as being correct... And you already guessed how I learned this tidbit.
5) The blade was too tall to get sighted in. Easy fix; file it down, cold blue.
Once all this was accomplished, it -is- a very nice sight. In their defense, who knows where the tolerances were on my rifle, and where they were on their test rifle. Just keep in mind that it may, or may not be an easy install on -your- rifle.
In my case, a flex-hone may have made my life easier---- certainly an adjustable reamer would have! Check with your machinist if you run into this.
It certainly explains the prevalence of set screws incorporated in all those flash hiders that also use the front sight pin.
I hope this helps, and I hope that I didn't stray too far off-topic!