Observed:
When reloading a magazine, its weight is not taken into account for calculating the maximum stamina.

Example:
If a player's combined gear weight is just above the amount that allows the player to run/sprint, then reloading the main weapon will sometimes reduce the gear weight just below this threshold (depending on the magazine weight) and it will let the player run or sprint for the time it takes for the reloading animation to finish.

It should be noted that this is only the case when reloading partially expended magazines, since empty magazines will disappear and the gear weight is decreased accordingly.

Expected:
The gear weight of a player should be constant while reloading.