How you load your ammo when performing a precision evaluation is important. You do not wish to simply load up a magazine and blast 10 rounds down range. That will heat the barrel and yield inaccurate results.
A common method is to single load rounds and allow the barrel to cool for 60 seconds between shots. This is the method that the author uses. But, during a recent range trip, the author witnessed an individual doing this by placing the cartridge on top of the magazine. This can lead to the bullet itself becoming disfigured upon entry into the chamber.
Standard practice is to load the cartridge into the magazine, and put the magazine into the rifle as the barrel cools. But how much does attention to this one detail matter?
The author set out to discover the answer to this question. Using known ammo, a 10 round group was fired from 100 yards. New cartridges were placed on top of the magazine, instead of loaded into the magazine. The bolt was sent home each time. Ammo used was Federal Gold Medal Premium, and Fiocchi Exacta. Both loads utilize the Sierra Match King 77 grain projectile. Both loads are capable of 1 MOA groups in the author's SPR.
As you can see, the results were 2 MOA groups by both loads.
A third group was fired, using Hornady Black 75 grain ammo. This load is accurate, but not as much so as the other two. It typically averages a 2 MOA group out of the author's SPR, and it did again this day. This group was fired by single loading the cartridges into the magazine as per standard protocol.
Attention to detail matters.