I put the trijicons on my 3rd gen G20. three greens
I debated putting on a different color front but opted for three greens because that's what I'm used too. I've got enough muscle memory there's no way I could mis-index the sights plus if I did the spacing would be way off.
One has to focus on keeping those three dots aligned up perfectly to shoot small holes in paper, rapid firing takes muscle memory which is what you're going to need anyways because the muzzle flash will mess up your ability to align the dots in a dark environment.
underwood uses a flash suppressed powder, something to consider in a carry gun if you're heading to your stands at night.
