A 39 $ red laser bore sighter is available at Walmart. I make a "target" out of reflective thumb tack trailmarkers, using five arranged in a cluster, you can use it in bright light conditions if you use a reflective target, I have mine set up at 50 yds, if I want to "get on the paper" with a centerfire rifle I use a ballistic chart and it will usually get me there.
It should work real well for rimfires. I have even used it for iron sights.