In my experience, red blooms too much in direct sunlight whereas green is a more refined dot. If you are only shooting at an indoor range either should be fine.
For general use though, green does behave more efficiently to the human eye in a range of varying light levels. I have fiber optic pins on the sight for my compound bow with green, red and orange pins right next to each other for various distances. The green is the first I can see clearly at dawn and the last I can still see clearly at dusk. I chose it specifically for my 20 yard pin because of this.
Sent from my iPhone using Tapatalk