Can you clarify—I may have misunderstood but I’d thought you said you were using a chrono’d velocity from a different gun. Did you chrono that lot of ammo in that specific gun? If not, thats what you need, the same ammo will have different velocity between different guns.
That would be great, but ime unlikely. This is quite possibly the issue. In some ways its an issue of expectation—the shots will disperse from average point of impact into a bell curve with MOST shots falling relatively close to center, but a predictable and significant portion of them will land 2 and 3 standard deviations outside that “core” group—thats all BEFORE any human error. So any random 3 or 5 shot group is relatively likely to not have one of those “ 3sd’s outside the core” shots so it’ll look “better”, but may very well still be well off true center of cone. Its a very, very rare rifle that actually has a .5moa cone. So if you are shooting 3-shot groups and often getting .5moa results, as soon as you go to a 10+ round group you will see that double or triple in size. Thats not human error, thats just how it works. The key is that unless you have an uber-precise rifle (which ime isnt common even with a full custom), its going to wind up as a 1.2 or 1.5moa group, and any one 3-shot group could be centered well off from the actual center of the bigger group—easily more than a scope-click off.
