You don't need a pole at 8 m to measure distance. Simply add a Directional Displacement result in the X axis. That will tell you the position of the bullet from its starting point.
To save computational time, you should Duplicate this analysis and convert it to a Rigid Dynamics analysis. That will change all the bodies to rigid bodies since you don't care about the stress and strain in the bullet or the barrel and you are incurring a large cost in computational time and space to store the results for every node when you don't care about anything other than the location of the center of mass.
The equations you wrote are wrong. Look up the equations for Uniformly Accelerated Motion. Gravity is an accelerationthat is pulling the bullet down. You could add Standard Earth Gravity to your simulation to cause the bullet to drop down as it moves horizontally along the X axis.
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