Regarding shot timing and bore temperature . . .
Shoot 3 or 4 rounds to get the barrel fouled and warm.
Fire each shot at the same time interval. 30 seconds, 1, 2 or 3 minutes apart. Whatever you want.
Chamber each round 10 or 15 seconds then fire it. Each round needs the same chamber time else its powder will be at a different temperature for each shot; velocity will vary with powder temp. Hotter powder produces faster velocities.
And use the "SAAMI Twist" which is a repeatable way of taking a cartridge from its box, turning it end over end, then holding it horizontal as its loaded in the rifle. Then the rifle is handled the same way each time a round's fired. All this does is repeatably distribute the powder in the case for more uniform ignition and burning. Page 95 and 96 in the following SAAMI link has the instructions.
Great values of standard deviation of muzzle velocity is under 10 fps. That said, many a rifle will shoot well under 1 MOA at 1000 yards with standard deviations in the 20's. That's caused by how the barrel whips in the vertical axis when shot. Slower bullets leave when the muzzle axis points at a higher angle while its swinging up; faster ones leave sooner while that axis is at a lower angle on its up swing. This often happens and it sometimes makes long range accuracy better than short range accuracy.