You can use the excellent Ultradot 25. It works fine with any 1" rings. In fact, it comes with I" weaver style rings, but you can certainly use it in your Ruger rings, too. I use this same red dot on several guns, including my GP-100 and a Marlin 336. It is a bit pricey, yes, but it is guaranteed for life, though the odds of ever needing that guarantee are remote. Ultradots are one of the most used red dots on the bullseye target circuit and are about as recoil proof as a red dot can get.
I especially like Ultradots on rifles for the way they just jump right up in line with the target. They're actually faster than using iron sights to get on target and they definitely allow for more accurate shooting than irons. They're not affected by rain or snow like a scope and if you're hunting in dark timber, nothing beats a red dot for sight visibility.
I'm going with North Country Gal on this one. I've got an UltraDot 30 that I had on my 22/45, but that I've since moved to my 10/22. It completed the rifle perfectly and it's my favorite plinking gun of all. Armed with a box full of CCI Mini Mags and my 10/22 + UltraDot, there isn't a tin can, tiny pumpkin or potato in three counties that is safe from me. Muahahaha!
The UltraDots are well-made, highly durable and very accurate. I find my UD dot to be far more than adequate in size, shape and consistency. Bright enough for daylight use, but can be turned down for dawn or dusk shooting. No fancy bells and whistles. No weird reticles, no green or blue or purple. Just a red dot that is accurate and consistent.