I just look at published reload data with velocities listed. That gives me a ballpark number. If my cheap, set up gives velocities close to those publish figures, I call it close enough.
If my numbers are off, then I know not to believe it.
Simple....
Have seen plenty of rifles that vary 200+fps from published data, in rifle cartridges that get around 3000 fps even when using exactly the same components in the same barrel length. Have seen even more variation when changing bullets of the same weight, especially today when bullet construction can be far different than it was back when almost every bullet was a simple cup-and-core.
Then there's the effect of changing seating depth, different manufacturing batches of powder, etc.
I prefer knowing the muzzle velocity, not coming within 10% or so.
