I've found that there can be significant differences in POI if even 1 small aspect has changed.

If you develop a load for a rifle with tight, perfectly centered groupings, then build more rounds with the same recipe, only using the same brand/model of primer - but from a different manufactured lot #, you'll get different POI results.

The same holds true for using the same lot of reloads on a different rifle. If you had 2 identical rifles whose barrels were manufactured one right after the other, you'd have (potentially) vastly differing POI results. One rifle may shoot dime-sized groups at 100 yards while the next rifle shoots paper plate sized groups.