Considering most ammo is tested for MV on 20 and 24" barrels, what would be your guesstimate on how much MV  is lost when testing MV on
a 16" barrel with Fed printed 3165 MV and ADI Matchking at 3277 MV ?

25 fps per inch

You're talking about the ADI 55gr Blitzking from the other thread? Looks like 2848fps at 45F



This is the same stuff as the current ADI World Class, before the rebranding

Every barrel/bullet combo will be different. A chronograph will tell you the actuals.
MidwayUSA Competition Dynamics Chronograph

It's an affordable one, worth the investment.

I have an update on the MV of the rounds I normally shoot that I thought I would share for those that are helping me.

The gun is a S&W sport 15 AR 5.56 with a 1 to 9 twist and a 16" free floated barrel. All rounds are 55 grain.

The coronagraph gave these  MV numbers.

IMI MV =  2810, 2950, 2970, 2910 for an average of 2945. We threw out the first shot of 2810.

Fed MV = 3010, 3110, 3110 for an average of 3070. The box says MV is 3165.

ADI MV = 2910, 2860, 2880 for an average of 2880. Their email said 3277.

My friends handloads = 2820, 2790, 2840 for an average of 2816.

Someone mentioned that 25 FPS per inch of barrel. Seems to be close.

Now that I have this information I'm not sure what to do with it.

Your ADI ammunition is loaded with the Sierra 55 grain BlitzKing.  This factory loaded ammunition is a solid 1 MOA load.

For the moment, we'll pretend that your height of sight above bore is 2.6" and that you are shooting at standard atmospheric conditions.  You'll need to determine what your values are for more precise calculations.  Using your muzzle velocity of 2880 FPS and a 100 yard zero, the chart below shows your come-ups out to 325 yards.




....

Sight height above the bore is 2.5".
The groups today were out to 3"- 3.5" at 100 from a bench rest. Sadly I mixed rounds together so I'm not positive about the groups.
Scope changes were made. I don't have the smoothest pull in the MBT 2 trigger.

Not sure I understand the chart. What are comeups?
If the left hand column 100 yard zero, at 225 yards mean I will be 2" high? At 325 I will be 5" high with a 100 yard zero?

Can you tell I'm pretty much lost?