Walther LG 400 MONOTEC – testing NEW air rifle

After the competition, I am testing my new the Walther LG400 MONOTEC air rifle. Shooting at a target, checking speed and conclusions. Why is it losing zero from time to time?

I show what it is and how the chronograph works on the unique Walther LG400 MONOTEC rifle in the version for field shooting with a power of 16 Joule.