Greetings @Jhon,
Your chrono coukd be right if your friends ammo is the Superformance type which claims 3,000 fps in a 24 inch barrel. Otherwise bright sunlight can cause reading errors, often high. In any case as the rifle has a 16 inch barrel the best data to use is that umder the pistol section on the Hodgdon Load Data website. This is for a 15 inch barrel. H4895 is AR2206H, Varget is AR2208 and Benchmark 8208 is IMR8208XBR. I'm assuming you will be using Hornady cases which have a weight and hence capacity close to the Winchester cases that Hodgdon used in the data. Usung the data you should be able to work up to about 2,700 fps in your barrel. Hornady cases weigh around 165 grains or a little more without primer. Heavier cases will give a both more velocity and pressure. If you are chronographing try for an overcast day which should give more reliable readings.
Regards Grandpamac.
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