Good article on best distance to zero pistol optic.

[Racer88]

An Official Journal Of The NRA | Best Distance to Zero a Pistol-Mounted Red Dot

With the explosion in popularity of pistol-mounted red-dot sights, deciding what distance at which to zero has become a pressing issue.

www.shootingillustrated.com

I zeroed mine at 25 yards, and by what I see in this article that will work best at the various likely "defensive" distances.

 

[Bongo Lewi]

For pistols with a red dot, I go with 25. Mainly because the reason for having the RDS is to be able to land a long shot. On the rare occasion that I zero iron sights (replacing or upgrading), it's 15. Mainly because I'm anal about things being "right". In most self-defense situations, it's up close and personal so you don't have time to line up the sights before pulling the trigger. But if I do.... I know they are aligned. With a few exceptions (as with some 1911's or target .22's) your only options are pushing left or right. If you have to aim with iron sights, it matters that the back and front are perfectly aligned.

I've had a Ransom Rest for a couple of years. It's a luxury item for sure but if you want to spend the time to get a handgun really dialed in, it is pretty useful. Most of the time I use it for my 1911's.