The expansion of the sight should be considered to be related to the accuracy of the weapon. When the scope is extended to the limit, the gun is the least accurate. The gun is most accurate when the scope is minimized. When the scope is enlarged by 50%, the accuracy of the gun is also 50%.
Intuitively, we can predict that at a given inflation rate (say, 25%), the gun will also have 25% accuracy. For example, consider two MP5s. The first one has been shooting continuously for a long time, and the scope has reached 50% expansion. The second shot has been fired for a long time, but it is no longer fired. The sight of this gun is shrinking (continuous shooting has reached its maximum expansion), and it is now at 50%.
The usual advice to improve accuracy is not to pull the trigger all the time. Players should use some shots, pause after several rounds of firing, wait for the gun to return, and then make some shots in the next round. The specific method is to hit three rounds every two seconds, which is better than hitting three rounds first and then hitting a large number of miss shots.
The size of the sight is an attempt to show the accuracy of the bullet's impact point at a certain moment when shooting.
In practice, it is found that after a long enough continuous shooting makes the scope reach the maximum level, the first bullet in the next round will be very accurate after a pause of about 0.5 seconds, but the subsequent bullets will immediately return to the extremely inaccurate level.
To put it simply: after several shots, if the player continues to drive the next round without returning the weapon, the first bullet is still completely accurate, and then the weapon immediately returns to a very inaccurate level.
This feature is consistent with all automatic weapons.