Velocity spread - what most folks refer to in "ES" or Extreme Spread, or "SD" or Standard Deviation" - doesn't tend to make much difference inside 300yrds. The further out you shoot, the more it will matter.

Get your ES under 20 for a hunting load and you're doing better than average. Get it into single digits and you're chasing top level benchrest quality consistency powder charge, neck tension, primer brisance, seating depth, bullet weight...

The easiest "trick" in finding a low velocity spread, low ES, is to find that happy window in your powder charge in which small changes in powder charge don't result in much if any change in velocity. There was a thread on OCW method recently in which I posted a picture, read that thread and you'll get a bit of a picture as to how it's used to find a low ES.